Humberto Lugo-Vicente MD FACS FAAP

25/08/2025

Disponible ya! -
LA PICCOLA REGINA
ISBN13 - 979-8298446280
450 paginas.
https://www.amazon.com/dp/B0FMYM5P42
"...nunca confíes en la tumba que no has preparado tu misma..."

02/08/2025

PSU AUGUST 2025 Review -

Hypertrophied Nerves in Hirschsprung's Disease

Hypertrophied nerves play a pivotal role in the diagnosis and understanding of Hirschsprung's disease (HD), serving as both a diagnostic hallmark and a reflection of the underlying neuroanatomical disruption. HD is defined by the congenital absence of ganglion cells in the distal bowel, with submucosal nerve hypertrophy often emerging as a secondary hallmark due to the proliferation of extrinsic cholinergic nerves in the aganglionic segment.

The histological triad—absence of ganglion cells, presence of hypertrophic nerves, and abnormal acetylcholinesterase (AChE) activity—remains the gold standard for diagnosis. However, the role and reliability of hypertrophied nerves have been subject to scrutiny and evolution across studies.

A key point established in one 2016 study is that hypertrophied nerve fibers (defined as >40 µm in diameter) are not uniformly present in all cases of HD. Particularly in long-segment HD and total colonic aganglionosis, as well as in neonates and premature infants, hypertrophy may be absent. The study found that the absence of hypertrophied nerve fibers in an aganglionic biopsy predicted a transition zone proximal to the rectosigmoid colon, with a specificity of 77.3%. This highlights that while nerve hypertrophy supports the diagnosis, its absence—especially when combined with aganglionosis—may suggest a more extensive disease and requires further attention in surgical planning.

Another study from 2023 emphasizes the relationship between hypertrophic nerves and the transition zone (TZ), a histopathologically abnormal yet ganglionated segment located between aganglionic and normal bowel. Histological markers of TZ include submucosal nerve hypertrophy, myenteric hypoganglionosis, and partial aganglionosis. The identification of hypertrophied nerves within the TZ suggests that this region is not only histologically abnormal but may also be functionally compromised. Surgical precision in identifying the proximal extent of the TZ is crucial, as residual TZ tissue post-surgery may lead to obstructive symptoms.

Calretinin immunohistochemistry (IHC) has become an increasingly favored adjunct in identifying ganglion cells and evaluating the TZ. Recent studies demonstrate calretinin's reliability in clearly distinguishing aganglionic from ganglionic bowel. Notably, the 2024 Heidelberg study reports that switching from AChE histochemistry to calretinin IHC improved diagnostic confidence, reduced the need for repeat biopsies, and enabled earlier definitive surgical intervention. The strength of calretinin IHC lies in its consistent staining patterns and independence from patient age—a critical advantage over AChE staining, which is unreliable in neonates due to immature cholinergic innervation.

The role of calretinin is further emphasized in a 2021 institutional review, which demonstrated that calretinin staining was always positive in the presence of ganglion cells and always negative in aganglionic samples, regardless of nerve hypertrophy or biopsy depth. This underscores its utility not only in diagnosis but also in evaluating whether hypertrophied nerves correspond to functional abnormalities, as hypertrophy alone does not equate to pathology if ganglion cells are present and calretinin is positive.

More recent developments in digital pathology and artificial intelligence are enhancing diagnostic accuracy. A 2023 study introduced deep learning models capable of detecting ganglion cells and hypertrophic nerves in histological slides with over 90% accuracy. This AI-based approach aids in standardizing diagnosis, reducing interobserver variability, and identifying TZ features such as coexisting ganglion cells and hypertrophied nerves—regions requiring extra scrutiny due to potential functional compromise.

However, challenges remain. A 2023 study reviewing inconclusive full-thickness biopsies found that re-evaluation using both hematoxylin and eosin (HE) and IHC resolved only a fraction of the inconclusive cases, with most remaining non-diagnostic. This points to persistent ambiguity in the histopathological criteria and the need for more robust, perhaps integrative, diagnostic protocols combining histology, IHC, AI, and clinical context.

Additionally, the concept of the "shore break" (SB)—an endoscopic marker for the transition from peristaltic to non-peristaltic bowel—was recently correlated with the histopathological TZ. A 2023 surgical pathology study demonstrated that in all examined cases, the SB coincided with histologic features of the TZ, including nerve hypertrophy. This finding offers a functional correlate to histologic abnormalities and suggests a potentially valuable intraoperative tool for guiding resection margins.

In practice, hypertrophied nerves alone are insufficient for diagnosis without correlating evidence of aganglionosis. Their diagnostic value increases when viewed alongside absent ganglion cells and other markers like calretinin negativity or AChE activity. Moreover, while hypertrophy is a common feature in classic HD, its absence—particularly in certain subtypes or younger infants—should prompt consideration of disease extent and histologic variants rather than immediately excluding HD.

In conclusion, hypertrophied nerves in HD represent both a diagnostic clue and a histologic signature of the abnormal neurodevelopment that defines the disease. Their presence, distribution, and relationship to ganglion cells must be interpreted in the broader context of age, disease subtype, biopsy technique, and staining method. Advances in IHC and AI tools continue to refine this interpretive framework, but the complexity of HD pathology demands continued vigilance, multidisciplinary communication, and tailored surgical decision-making to ensure optimal outcomes.

References:
1- Narayanan SK, Soundappan SS, Kwan E, Cohen RC, Charlton A, Cass DT: Aganglionosis with the absence of hypertrophied nerve fibres predicts disease proximal to rectosigmoid colon. Pediatr Surg Int. 32(3):221-6, 2016
2- Zemheri E, Engin Zerk P, Ulukaya Durakbasa C: Calretinin immunohistochemical staining in Hirschsprung's disease: An institutional experience. North Clin Istanb. 31;8(6):601-606, 2021
3- Matsukuma K, Gui D, Saadai P: Hirschsprung Disease for the Practicing Surgical Pathologist. Am J Clin Pathol. 159(3):228-241, 2023
4- Yasui Y, Kido M, Nakamura K, Kuwahara T, Hirotani T, Tamura R, Kumagai M, Shimasaki M, Yamada S, Okajima H: The Junction Between the Peristaltic and Non-peristaltic Bowel (Shore Break) is Found in the Transition Zone in Hirschsprung's Disease. J Pediatr Surg. 58(11):2160-2164, 2023
5- Korsager LEH, Bjørn N, Ellebæk MB, Christensen LG, Qvist N: Full-Thickness Re**al Biopsy in Children Suspected of Having Hirschsprung's Disease: The Inconclusive Biopsy. Children (Basel). 10(10):1619, 2023
6- Duci M, Magoni A, Santoro L, Dei Tos AP, Gamba P, Uccheddu F, Fascetti-Leon F: Enhancing diagnosis of Hirschsprung's disease using deep learning from histological sections of post pull-through specimens: preliminary results. Pediatr Surg Int. 40(1):12, 2023
7- Romero P, Burger A, Wennberg E, Schmitteckert S, Holland-Cunz S, Schwab C, Günther P: Clinical Relevance of Pathological Diagnosis of Hirschsprung's Disease with Acetylcholine-Esterase Histochemistry or Calretinin Immunohistochemistry. Children (Basel). 11(4):428, 2024

02/08/2025

PSU AUGUST 2025 Review:

Nutcracker Syndrome

Nutcracker Syndrome (NCS) in children presents a diagnostic and therapeutic challenge due to its nonspecific symptoms, varied clinical presentation, and lack of standardized criteria. Despite its rarity, recent studies offer increasing insight into its pathophysiology, diagnostic approaches, and treatment strategies.

NCS refers to the compression of the left renal vein (LRV), most commonly between the aorta and the superior mesenteric artery (SMA)—a configuration termed anterior NCS. Less commonly, the LRV may be compressed posteriorly between the aorta and vertebral column, or even have dual compression in cases of vascular anomalies like circumaortic veins. In pediatric populations, anterior NCS is overwhelmingly dominant. Compression results in renal venous hypertension, leading to the development of collateral venous pathways and subsequent clinical symptoms.

The most frequent presenting symptom in children is hematuria, observed in approximately 55% of cases, followed closely by proteinuria in nearly half of patients. Both microscopic and macroscopic hematuria have been documented, with the former often discovered incidentally. Flank pain is less common, found in roughly one in five cases, despite being traditionally associated with the syndrome. These symptoms are believed to arise from venous hypertension causing rupture of small varices in the renal collecting system, or from immune-mediated mechanisms triggered by abnormal venous flow. Additionally, fatigue, orthostatic intolerance, and dizziness have been linked to autonomic nervous system involvement.

Orthostatic proteinuria in children is often attributed to positional changes affecting renal hemodynamics. A compelling finding is the role of a low body mass index (BMI), which reduces mesenteric fat that otherwise supports the SMA, increasing the likelihood of renal vein compression. Some studies even suggest resolution of symptoms with weight gain, supporting a conservative approach in many pediatric patients.

Diagnostically, Doppler ultrasonography (DUS) is the frontline noninvasive tool, favored for its accessibility and safety. In pediatric NCS, peak velocity ratios of the LRV between the aortomesenteric and hilar portions greater than 4.7 to 5.0 are considered indicative. However, the technique is operator-dependent and may yield variable results in children due to patient cooperation and anatomical factors.

Cross-sectional imaging like computed tomography angiography (CTA) and magnetic resonance angiography (MRA) adds anatomical detail. MRA, in particular, offers a radiation-free alternative with high accuracy in assessing the SMA angle and LRV compression. In one study, pediatric NCS patients had a significantly lower SMA angle (mean ~26.5°) and a smaller aortomesenteric distance (~3.3 mm) compared to controls, reinforcing MRA's diagnostic utility.

Invasive studies, such as venography with pressure gradient measurement, are considered the gold standard but are reserved for ambiguous or refractory cases due to their invasiveness. They are more often used in surgical candidates, especially when conservative management fails after extended monitoring.

Treatment in children is typically conservative. The literature consistently supports this approach, with more than 86% of pediatric cases managed non-surgically and nearly 95% of these showing symptom resolution or improvement. Conservative management includes observation, weight gain, and, in some cases, pharmacologic therapy like angiotensin-converting enzyme inhibitors to manage associated orthostatic symptoms.

Surgical interventions, including LRV transposition, renal autotransplantation, and endovascular stenting, are reserved for persistent or severe cases, particularly when complications such as varicocele, pelvic congestion, or progressive pain are evident. However, their application in children is limited due to long-term risks, including stent migration and the potential need for reintervention.

Autonomic dysfunction in NCS has recently gained attention. A case-control study demonstrated that over half of the pediatric patients experienced orthostatic symptoms, primarily dizziness and fatigue. Holter monitoring revealed altered heart rate variability, suggestive of autonomic imbalance. These findings reinforce the systemic implications of LRV compression beyond renal manifestations.

Despite growing research, the overall quality of pediatric NCS studies remains limited, with most evidence derived from case reports or small case series. This hampers the establishment of standardized diagnostic algorithms and outcome benchmarks. Nevertheless, the literature increasingly emphasizes a diagnostic pathway beginning with DUS, followed by MRA when needed, and cautious use of invasive diagnostics. A trial of conservative treatment with close follow-up is generally endorsed before considering surgical options.

In conclusion, Nutcracker Syndrome in children is a multifaceted condition marked by variable symptoms, often subtle or nonspecific, and requiring a tailored approach. High clinical suspicion, especially in cases of unexplained hematuria or proteinuria, is key. Noninvasive imaging remains central to diagnosis, and most cases can be managed without surgery. However, ongoing research is essential to clarify its natural history, refine diagnostic criteria, and optimize management strategies, especially in symptomatic or refractory cases.

References:
1- Nalcacioglu H, Ceyhan Bilgici M, Tekcan D, Genc G, Bostanci Y, Yakupoglu YK, Sarikaya S, Ozkaya O: Nutcracker Syndrome in Children: Role of Doppler Ultrasonographic Indices in Detecting the Pattern of Symptoms. J Clin Med. 7(8):214, 2018
2- Agarwal A, Litra F, Barr LL: A Rare Cause of Abdominal and Flank Pain in Children: Nutcracker Syndrome. Cureus. 13(7):e16422, 2021
3- Kolber MK, Cui Z, Chen CK, Habibollahi P, Kalva SP: Nutcracker syndrome: diagnosis and therapy. Cardiovasc Diagn Ther. 11(5):1140-1149, 2021
4- Atasoy D, Cansu A, Bekirçavusoglu AF, Özdogan EB, Ahmetoglu A: The utility of magnetic resonance angiography in children with nutcracker syndrome. Turk J Med Sci. 51(5):2396-2402, 2021
5- Meyer J, Rother U, Stehr M, Meyer A: Nutcracker syndrome in children: Appearance, diagnostics, and treatment - A systematic review. J Pediatr Surg. 57(11):716-722, 2022
6- Dönmez YN, Koksoy AY, Bako D, Giray D, Epcacan S: Autonomic Disturbances in Children with Nutcracker Syndrome: A Case Control Study. Indian Pediatr. 61(12):1114-1118, 2024

02/08/2025

PSU AUGUST 2025 Review...

Bronchial Atresia

Bronchial atresia is a rare congenital condition marked by the interruption of a bronchial segment, most often at the segmental or subsegmental level. This interruption leads to the accumulation of mucus in the obstructed bronchial stump—referred to as a bronchocele or mucocele—and hyperinflation of the distal lung parenchyma. This hyperinflation occurs due to collateral ventilation from nearby alveoli, as air enters the obstructed segment through pores of Kohn, canals of Lambert, or channels of Martin, but cannot exit efficiently. The segment becomes overinflated and may appear more lucent on radiographs, often prompting further evaluation. Although the condition is typically discovered incidentally, particularly in adolescents and young adults, it can also present with recurrent pulmonary infections, dyspnea, cough, hemoptysis, or even pneumothorax.

Computed tomography has become the gold standard for diagnosing bronchial atresia. Radiographically, the condition often appears as a perihilar mass with adjacent hyperlucency. On high-resolution CT, hallmark findings include a branching or tubular mucocele with surrounding emphysematous lung. The characteristic "finger-in-glove" sign is frequently observed due to mucoid impaction within a dilated bronchus. In a study reviewing 23 confirmed cases, every patient exhibited both a mucocele and hyperinflation of the surrounding parenchyma. These findings were consistently unilateral, most commonly affecting the apicoposterior segment of the left upper lobe, followed by the right lower and upper lobes. Additional findings such as subsegmental atelectasis, bronchial wall thickening, and small cysts may occur, though less frequently.

Histologically, bronchial atresia reveals a blind-ending bronchus filled with mucus, surrounded by hyperinflated alveoli. There is typically no acute inflammation unless secondary infection has occurred. Pathological examination of surgical specimens frequently confirms emphysematous change, mucus plugging, and bronchiectasis. Occasionally, the lesion coexists with other congenital lung anomalies such as congenital pulmonary airway malformation (CPAM), bronchopulmonary sequestration, and lobar emphysema. These associations suggest a common developmental pathway or timing in embryogenesis, although precise causative mechanisms remain speculative.

There is considerable debate regarding the management of bronchial atresia, particularly in asymptomatic individuals. While some centers advocate for surgical resection even in asymptomatic patients to prevent long-term complications such as infection or damage to adjacent lung tissue, others favor a conservative approach with careful monitoring. A pediatric cohort followed over a median of 29 months demonstrated that conservative management could be safe and effective in selected patients. Of the 12 children monitored without surgery, only one became symptomatic during follow-up. This finding supports the position that surgery should be reserved for patients who develop significant symptoms or complications.

In contrast, adult cases are more likely to be managed surgically, especially if there is diagnostic uncertainty or persistent symptoms. Surgical intervention can include lobectomy, segmentectomy, or wedge resection, depending on the extent and location of the lesion. Recent advances in thoracoscopic techniques have made minimally invasive resection a viable and often preferred option. Case reports of thoracoscopic sublobar resections in adults have shown good outcomes, with resolution of symptoms such as cough, recurrent fever, or dyspnea. Importantly, three-dimensional CT reconstruction has emerged as a valuable tool in surgical planning by clearly delineating the absence of bronchial branches and helping define resection margins.

Operative data from adult cases indicate that thoracoscopic resection is safe, with minimal blood loss and short hospital stays. Common postoperative complications include air leaks and minor pneumothorax, typically managed conservatively. Histologic analysis after surgery often confirms the diagnosis and may reveal additional findings such as infection, bronchiectasis, or associated anomalies. In one surgical series, 5 out of 8 patients had postoperative complications, all of which were minor and resolved with conservative measures. This supports the notion that while surgery carries some risk, it is generally well tolerated and often curative in symptomatic patients.

Despite its rarity, bronchial atresia may be underrecognized. Improved imaging technology has led to more frequent incidental discoveries, particularly during evaluation for unrelated conditions. The diagnostic process relies heavily on high-resolution imaging, and in some cases, bronchoscopy may aid in detecting a blind-ending bronchus. However, a normal bronchoscopy does not rule out bronchial atresia, especially if the lesion is peripheral. Clinical awareness and radiologic expertise are essential for accurate diagnosis and appropriate treatment planning.

Given the association of bronchial atresia with other congenital pulmonary abnormalities, a multidisciplinary approach is often beneficial. Radiologists, pulmonologists, thoracic surgeons, and pediatric specialists must collaborate to determine the best course of action for each patient. In children and adolescents, conservative management with structured follow-up can be effective, particularly in asymptomatic cases. In adults or patients with recurrent infections or significant functional impairment, surgical resection remains the standard of care.

Ultimately, bronchial atresia represents a spectrum of clinical presentations, from benign incidental findings to complex symptomatic cases requiring surgical intervention. The decision to operate must balance the risks of surgery with the potential for disease progression or complications. Long-term prognosis is excellent in most cases, whether managed conservatively or surgically. However, close clinical monitoring and patient education are critical, especially for those who forgo surgical treatment. Early recognition and individualized management strategies offer the best outcomes for patients with this uncommon but important congenital anomaly.

References:
1- Wang Y, Dai W, Sun Y, Chu X, Yang B, Zhao M: Congenital bronchial atresia: diagnosis and treatment. Int J Med Sci. 9(3):207-12, 2012
2- Traibi A, Seguin-Givelet A, Grigoroiu M, Brian E, Gossot D: Congenital bronchial atresia in adults: thoracoscopic resection. J Vis Surg. 3:174, 2017
3- Puglia EBMD, Rodrigues RS, Daltro PA, Souza AS Jr, Paschoal MM, Labrunie EM, Irion KL, Hochhegger B, Zanetti G, Marchiori E: Tomographic findings in bronchial atresia. Radiol Bras. 54(1):9-14, 2021
4- Zarfati A, Voglino V, Tomà P, Cutrera R, Frediani S, Inserra A: Conservative management of congenital bronchial atresia: The Bambino Gesù children's hospital experience. Pediatr Pulmonol. 56(7):2164-2168, 2021
5- Hutchison MJ, Winkler L: Bronchial Atresia. 2023 Jun 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–.
6- Samejima H, Ose N, Nagata H, Funaki S, Shintani Y: Thoracoscopic sublobar resection for congenital bronchial atresia in adults: a report of three cases. Gen Thorac Cardiovasc Surg Cases. 14;2(1):92, 2023
7- Pasqua N, Bresesti I, Zirpoli S, Ghezzi M, Gentilino V, Pederiva F: CONGENITAL BRONCHIAL ATRESIA: TO SURGICALLY TREAT OR CONSERVATIVELY MANAGE? A SYSTEMATIC REVIEW. J Pediatr Surg. 16:162368, 2025

31/07/2025

The August 2025 edition of "PEDIATRIC SURGERY UPDATE" is now available:
👉 https://pedsurgeryupdate.com/
Don't forget to check the Index section to access previously published reviews:
👉 https://pedsurgeryupdate.com/indice.htm

Index database

17/07/2025

Experiencia LAPAROSCOPICA EN NIñOS...del Dr Lugo-Vicente:

Pediatric Laparoscopic Surgery in Puerto Rico:

1994 - 1st laparoscopic cholecystectomy in a child

1996 - 1st laparoscopic appendectomy and splenectomy in a child

2002 - 1st laparoscopic fundoplication in a child

2007 - 1st laparoscopic adrenalectomy in a child

2008 - 1st laparoscopic nephrectomy in a child

2012 - 1st laparoscopic esophagomyotomy (Heller) in a child.

CITAS - (787) 340-1868

17/07/2025

Cicatrices después de una esplenectomía laparoscopia en un niño...2007...

Citas (787) 340-1868

**29 años haciendo laparoscopia en niños**

09/07/2025

Como he escrito esta biblioteca electrónica de cirugía pediátrica desde el 1993…me da la oportunidad de hacerle hincapié a los residentes de datos que pueden corroborar como evidénciales en el manejo de condiciones quirúrgicas…

Index database

02/07/2025

PSU July 2025 Issue:

Paronychia

Paronychia in children, though common, presents with a spectrum of causes, clinical behaviors, and treatment responses that set it apart from adult cases. Pediatric paronychia is typically classified as either acute or chronic, depending on the duration of symptoms. Acute cases often arise due to direct trauma to the nail folds—frequently from nail biting, finger sucking, or minor injuries from daily activities. Chronic paronychia, by contrast, tends to involve long-standing inflammation and is frequently complicated by repeated exposure to irritants and colonization by fungi such as Candida albicans.

Bacterial infection, particularly with Staphylococcus aureus, including methicillin-resistant strains (MRSA), remains the most common cause of acute paronychia in children. However, the microbiologic profile in pediatric populations may differ from adults due to unique behaviors like oral manipulation of fingers. This habit not only introduces skin flora but also oral anaerobes, contributing to a more diverse polymicrobial environment. Studies have shown that about half of pediatric paronychia infections may involve mixed aerobic and anaerobic bacteria. The presence of oral-derived organisms like Eikenella corrodens underscores the distinct etiologic pathways often involved in children.

One reported case of neonatal paronychia highlighted the interplay of self-soothing behaviors in a child with neonatal abstinence syndrome, which led to MRSA infection in both the second and third digits. Treatment required not only incision and drainage but also systemic antibiotic therapy. The episode underscores a broader concern—young children and infants, including neonates, are capable of developing paronychia under specific circumstances that involve repeated trauma to the nail bed or surrounding soft tissue.

Epidemiological studies reveal that paronychia and similar hand infections are among the most common pediatric hand surgery emergencies. A retrospective review of pediatric patients treated in emergency settings found that infections like paronychia represented over a quarter of all hand-related surgical cases. These infections occurred primarily at home and were most frequent among younger children, especially those under the age of six. This demographic pattern supports the hypothesis that immature motor control, high physical activity levels, and limited awareness of risk contribute significantly to the development of nail fold infections in this population.

Diagnosis is predominantly clinical, based on the presence of pain, erythema, and swelling of the nail folds. The accumulation of pus or fluctuant swelling often indicates abscess formation, which necessitates drainage. Laboratory studies, such as wound cultures, are helpful in guiding antibiotic therapy, especially when empiric treatment fails or MRSA is suspected. Radiographs may be warranted when there is suspicion of foreign bodies, fractures, or if osteomyelitis cannot be ruled out.

Management typically begins conservatively in early stages without abscess formation, using warm soaks and empiric oral antibiotics with gram-positive coverage. However, once abscess formation is evident, surgical drainage becomes the mainstay of therapy. In most pediatric cases, drainage combined with antibiotics yields rapid resolution. Common antibiotic choices include amoxicillin-clavulanate or clindamycin, with linezolid or trimethoprim-sulfamethoxazole used for MRSA coverage. Severe infections or cases in hospitalized children may require intravenous therapy, including vancomycin.

Beyond routine bacterial infections, chemotherapy-associated paronychia is an emerging concern in pediatric populations, especially as targeted cancer therapies become more common in children. Drugs like selumetinib, a MEK inhibitor approved for pediatric neurofibromatosis-related tumors, are associated with a high incidence of nail toxicity. Pediatric patients appear to have a higher susceptibility to paronychia from such agents compared to adults. The mechanism is believed to be related to both the cytotoxic effects of the drugs on epithelial cells and the mechanical trauma children experience more frequently due to higher physical activity.

Treating paronychia in children receiving chemotherapy is further complicated by the limitations of standard pharmacologic options. While doxycycline may be used in adults for its anti-inflammatory effects, it is contraindicated in young children. Instead, agents like azithromycin are considered more suitable alternatives, though definitive pediatric treatment protocols are still lacking. Preventive strategies, including minimizing nail trauma and improving caregiver education about nail care and hygiene, are critical but sometimes difficult to enforce in this population without affecting quality of life.

Finally, chronic paronychia in children is a distinct clinical entity. It often involves prolonged inflammation, with secondary colonization by fungal species. Unlike acute infections, chronic cases require a combination of antifungal therapy, environmental modifications to limit moisture and irritant exposure, and sometimes topical steroids to reduce inflammation. It is important to differentiate chronic paronychia from recurrent acute infections or other mimickers like herpetic whitlow, which may present similarly but require entirely different approaches.

Overall, paronychia in children demands tailored diagnostic and management strategies that account for their unique anatomical, behavioral, and immunologic characteristics. Effective treatment depends not just on resolving the immediate infection but also on preventing recurrence through behavioral guidance, environmental modification, and in certain cases, long-term therapeutic planning—particularly in children with underlying conditions or immunocompromise. As clinical awareness of the diverse presentations and challenges of pediatric paronychia grows, so too must research into evidence-based, pediatric-specific treatment protocols that address both common and rare forms of this deceptively simple but potentially serious condition.

References:
1- Grome L, Borah G. Neonatal Acute Paronychia: Hand (N Y). 12(5):NP99-NP100, 2017
2- Dizin F, Saab M, Mézel A, Guerre E, Chantelot C: Epidemiology of pediatric hand surgery emergencies. Retrospective study of 245 patients seen over 10 months in two referral centers. Orthop Traumatol Surg Res. 108(1):103067, 2022
3- McKean AR, Williams GJ, Macneal P, Moore LS, Idowu A, Milroy C: Paediatric paronychia: A single centre retrospective, microbiological analysis and national survey. J Plast Reconstr Aesthet Surg. 75(7):2387-2440, 2022
4- Borgia P, Piccolo G, Diana MC, Viglizzo G. Chemotherapy-associated paronychia: Do not forget the children. J Am Acad Dermatol. 88(1):e59, 2023
5- Macneal P, Milroy C: Paronychia Drainage. In: StatPearls

02/07/2025

PSU July 2025 Issue:

Transitional Zone Pull-Through

The treatment of Hirschsprung disease (HD) centers on surgical removal of the aganglionic segment of bowel and reconstruction with normally ganglionated colon. However, the existence of a "transition zone" (TZ)—a morphologically ganglionated but functionally abnormal segment of intestine that lies between the aganglionic and normoganglionic bowel—poses a persistent challenge. Resection of this segment is crucial, yet often incomplete, leading to what is referred to as a transition zone pull-through (TZPT). This complication is implicated in persistent postoperative obstructive symptoms and has historically driven the need for redo surgeries. Despite growing recognition, defining, identifying, and managing the TZ remains inconsistent across institutions and pathologists.

The histopathologic definition of the TZ lacks standardization. Criteria typically include partial circumferential aganglionosis, myenteric hypoganglionosis, and hypertrophy of submucosal nerves. Each of these features may present alone or in combination, contributing to the difficulty of intraoperative identification. For example, partial circumferential aganglionosis may involve a significant portion of the bowel wall, often more than one-eighth of the circumference, and is best visualized in transverse sections. Longitudinal or seromuscular biopsies are frequently inadequate to detect these features, leading to misidentification of bowel as normoganglionic. Myenteric hypoganglionosis presents as thin, underdeveloped ganglia lacking neuropil, which can be easily missed or misinterpreted. Submucosal nerve hypertrophy, defined in some studies as the presence of two or more nerves =40 µm in diameter per high-power field, is subject to age and location variability, further complicating its interpretation.

Recent histological studies underscore the importance of examining full-thickness transverse sections of the proximal resection margin to detect TZ features. Data suggests that the TZ can extend up to 10 cm in some patients, though the average length is closer to 2.6–5 cm in cases of rectosigmoid HD. Therefore, surgical resection that begins at least 5 cm proximal to the last biopsy with ganglion cells has become the de facto recommendation to minimize risk of TZPT. However, this strategy is complicated by the variable circumferential involvement and longitudinal extent of TZ histology, which are not always apparent intraoperatively.

Postoperative consequences of TZPT include persistent constipation, enterocolitis, and overall impaired bowel function. Yet, emerging evidence questions whether these outcomes are strictly attributable to retained TZ tissue. A recent study comparing postoperative complications in patients with normoganglionic neorectum (NNR) versus TZ neorectum (TZNR) found no significant difference in rates of Hirschsprung-associated enterocolitis (HAEC) or constipation. Similarly, long-term outcomes, including quality of life and need for interventions such as laxatives or botulinum toxin, were comparable between TZPT patients treated conservatively and those undergoing redo surgery. These findings challenge the dogma that any presence of TZ at the anastomotic site is necessarily pathologic.

Adding to this complexity is the phenomenon of postoperative remodeling. Glut1-positive submucosal nerve hypertrophy, previously considered a hallmark of retained TZ, has been identified in neore**al biopsies of patients whose primary resections were histologically complete. This suggests that nerve remodeling—possibly due to reinnervation or adaptation—occurs post-surgery and may mimic TZ histology. It complicates the interpretation of postoperative biopsies and raises concerns about over-diagnosing TZPT in patients with nonspecific symptoms.

While some centers advocate for aggressive surgical strategies to ensure complete resection of the TZ—including intraoperative frozen sections and extended resection margins—many pathology reports still lack clear documentation of TZ features at the proximal margin. A study reviewing pathology reports from 35 institutions found that most did not state whether TZ histology was present at the surgical margin. Intraoperative frozen sections were performed in only 23% of cases, and even when TZ features were evident histologically, they were frequently not reported. These gaps in communication contribute to clinical uncertainty and may delay or misguide postoperative management.

To mitigate the risk of TZPT and its complications, consensus guidelines recommend several practices: (1) full-circumference, full-thickness transverse biopsies at the proximal resection margin; (2) frozen section evaluation of the margin intraoperatively; and (3) explicit reporting of TZ features, including quantification of ganglion cell density, nerve hypertrophy, and circumferential involvement. Importantly, pathologists must be trained to recognize age-related and location-specific variations in innervation to avoid over-diagnosis.

The implications of TZPT reach beyond immediate surgical outcomes. Functional morbidity, including impaired continence and social limitations, can persist into adolescence and adulthood. Redo surgery, while potentially curative, carries increased risk for f***l incontinence and other complications. Thus, an individualized approach—considering the severity of symptoms, histologic findings, and patient/family preferences—is increasingly favored.

In summary, TZPT remains a significant and nuanced concern in the surgical management of HD. The interplay of anatomical ambiguity, histological complexity, and variable clinical outcomes calls for a multidisciplinary strategy integrating surgical expertise, robust pathology protocols, and long-term functional follow-up. As understanding of the TZ matures, efforts must focus on refining diagnostic criteria, improving intraoperative practices, and distinguishing histologic from functional pathology to optimize outcomes for patients with HD.

References:
1- Kapur RP, Kennedy AJ: Transitional zone pull through: surgical pathology considerations. Semin Pediatr Surg. 21(4):291-301, 2012
2- Kapur RP, Arnold MA, Conces MR, Ambartsumyan L, Avansino J, Levitt M, Wood R, Mast KJ: Remodeling of re**al innervation after pullthrough surgery for Hirschsprung disease: relevance to criteria for the determination of retained transition zone. Pediatr Dev Pathol. 21(6):1-12, 2018
3- Tomuschat C, Mietzsch S, Dwertmann-Rico S, Clauditz T, Schaefer H, Reinshagen K: The Length of the Transition Zone in Patients with Rectosigmoid Hirschsprung Disease. Children (Basel). 9(2):152, 2022
4- Torre LD, Domínguez A, Arnold M, Lovell M, Martínez D, Bischoff A, Wehrli L: Histological transitional zone pull-through in Hirschsprung disease. Postoperative functional results and current recommendations. Bol Med Hosp Infant Mex. 80(6):331-338, 2023
5- Beltman L, Labib H, Ahmed H, Benninga M, Roelofs J, van der Voorn P, van Schuppen J, Oosterlaan J, van Heurn E, Derikx J: Transition Zone Pull-through in Patients with Hirschsprung Disease: Is Redo Surgery Beneficial for the Long-term Outcomes? J Pediatr Surg. 58(10):1903-1909, 2023
6- Xu TO, Levitt MA, Feng C: Controversies in Hirschsprung surgery. World J Pediatr Surg. 7(3):e000887, 2024
7- Kapur RP, Prasad V, Srinivas S, Thomas E, Wood R, Smith C: Diagnosis and Prevention of Transition Zone Pull-through in Patients With Hirschsprung Disease. Arch Pathol Lab Med. 2025 Mar 11. doi:10.5858/arpa.2024-0429-OA.