Liu YF, Jin ZW, Han F
… +4 more, Zhang Y, Murakami G, Kim JH, Hirano-Kawamoto A
Pediatr Dev Pathol
· 2026 Mar · PMID 41918174
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OBJECTIVE: To identify a pathogenesis of retropharyngeal ectopic thyroid (ET) independent of the thyroglossal duct-derived usual ET. METHODS: We incidentally found a unilateral retropharyngeal ET in histological sections...OBJECTIVE: To identify a pathogenesis of retropharyngeal ectopic thyroid (ET) independent of the thyroglossal duct-derived usual ET. METHODS: We incidentally found a unilateral retropharyngeal ET in histological sections of a fetus at 28 weeks of gestational age (GA). The other histological sections from 21 embryos and fetuses (GA 5-8 weeks and 14-18 weeks) were examined to consider the pathogenesis. RESULTS: The retropharyngeal ET existed with the usual thyroid and it contained loosely distributed clusters of follicles without capsule. In the other 21 specimens, we found 3 candidates of the pre-laryngeal ET and they contained tightly packed follicles with a thick capsule. Thus, the retropharyngeal ET was most likely different from the pre-laryngeal ET in structure. At 6 to 7 weeks of GA, the developing thyroid was composed of abundant trabeculae. Notably, at their posterior ends, some trabeculae were adjacent to the hypoglossal nerve as well as the nodosa ganglion of the vagus nerve. CONCLUSION: During ascent of the hypoglossal nerve and nodosa ganglion, the trabecular thyroid seemed to descend along the anterior aspect of these nerve elements. Therefore, the nerve(s) might swipe and cut a trabecula to separate the fragment from the main lobes, resulting in the retropharyngeal ET.
Ishikawa R, Kondo T, Kondo S
… +3 more, Kishimoto T, Kagawa S, Haba R
Pediatr Dev Pathol
· 2026 Mar · PMID 41913561
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Glycogen storage disease type IV (Andersen disease) is caused by a deficiency of the glycogen branching enzyme. We report a case in which liver biopsy played a key role in establishing the diagnosis. A 2-year-old girl pr...Glycogen storage disease type IV (Andersen disease) is caused by a deficiency of the glycogen branching enzyme. We report a case in which liver biopsy played a key role in establishing the diagnosis. A 2-year-old girl presented to our hospital with hepatomegaly. Despite extensive testing, no definitive diagnosis was made, prompting a liver biopsy. The biopsy tissue revealed characteristic cytoplasmic inclusions. Genetic analysis identified a mutation in the gene, confirming the diagnosis of glycogen storage disease type IV. Various special stains were helpful in characterizing the accumulated substances.
Ding D, Ding D, Tian F
… +3 more, Zhao J, Feng J, Ma Y
Pediatr Dev Pathol
· 2026 Mar · PMID 41889101
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OBJECTIVE: To investigate the clinical and pathological features of pediatric SMARCB1/INI-1 deficient undifferentiated pancreatic carcinoma. METHODS: Two SMARCB1/INI-1 deficient undifferentiated pancreatic carcinomas dia...OBJECTIVE: To investigate the clinical and pathological features of pediatric SMARCB1/INI-1 deficient undifferentiated pancreatic carcinoma. METHODS: Two SMARCB1/INI-1 deficient undifferentiated pancreatic carcinomas diagnosed from 2021 to 2024 at the Children's Hospital of Fudan University were collected. The histomorphological features, immunohistochemical results, FISH test results, and clinical treatment courses were summarized, and the potential treatment was discussed in combination with the literature. RESULTS: Both cases were male, presenting with abdominal pain, abdominal distension, back pain, and weight loss, along with elevated serum CA125 levels. CT showed the pancreatic tail masses with heterogeneous enhancement. Microscopically, the tumor cells were arranged in nests and sheets, with focal glandular arrangement and exhibited abundant cytoplasm, vesicular nuclei, and distinct nucleoli with scant eosinophilic inclusions. Immunohistochemistry revealed CK, CK7, and CK19 expression and complete loss of INI-1 (SMARCB1) expression. The Ki-67 proliferation indices were 40%. FISH revealed SMARCB1/INI-1 gene deletion in both cases. After the surgery and chemotherapy, both patients died 42 days and 10 months after operation, respectively. CONCLUSION: SMARCB1/INI-1 deficient undifferentiated pancreatic carcinoma is a very rare, highly aggressive malignancy in children with dismal prognosis. It should be taken in consideration when encountering a pancreatic mass to avoid misdiagnosis in routine clinical work.
INTRODUCTION: Preterm infants are at risk for white matter brain injury characterized by periventricular leukomalacia (PVL) with exposure to in-utero inflammation. Our aim was to correlate placental pathology with PVL in...INTRODUCTION: Preterm infants are at risk for white matter brain injury characterized by periventricular leukomalacia (PVL) with exposure to in-utero inflammation. Our aim was to correlate placental pathology with PVL in a cohort of preterm infants. METHODS: All infants born <1500 g between Jan 1, 2017 and July 31, 2022 with placental pathology reports and neonatal outcome data on PVL were included in this study. Placental pathology findings were divided into 4 major categories (acute inflammation (AI), chronic inflammation (CI), fetal vascular malperfusion (FVM), and maternal vascular malperfusion (MVM)); each category was graded as absent, low-grade, or high-grade. RESULTS: We identified 263 infants with data for PVL and placental pathology. Gestational age (GA) averaged 28 completed weeks and mean birthweight was 1050 g. 11/263 (4.2%) infants had PVL. Acute inflammation was seen in 9/11 (82%) infants with PVL and only 101/252 (40%) of those without PVL ( = .01). Eight of the nine infants with PVL and AI (89%) had high-stage AI. In analyses adjusted for gestational age, the prevalences of CI, FVM and MVM were not significantly different between infants with or without PVL. CONCLUSION: In a large cohort of preterm infants, we demonstrate a strong association between AI in the placenta (histologic chorioamnionitis) and PVL in infants born <1500 g.
De La Riva I, Vivar K, Chou P
… +1 more, Gelarden I
Pediatr Dev Pathol
· 2026 Mar · PMID 41885761
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Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare, benign lesion composed of disorganized skeletal muscle and mesenchymal elements within the dermis and subcutis. It typically arises in midline locations of the head,...Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare, benign lesion composed of disorganized skeletal muscle and mesenchymal elements within the dermis and subcutis. It typically arises in midline locations of the head, neck, and trunk during infancy or early childhood. The full histopathologic spectrum of RMH remains incompletely characterized. We present 4 cases of RMH, including 1 with a previously unreported fibrocartilaginous component-highlighting a novel histologic finding. Clinical impressions varied, and RMH was not considered in any of the cases. This series expands the known morphologic range of RMH and emphasizes its potential to mimic other developmental lesions. Recognition of its distinct features may help avoid unnecessary interventions in pediatric patients.
Kodimyala R, Brannock K, Campbell A
… +3 more, Zajo K, Rose MJ, Kaumeyer B
Pediatr Dev Pathol
· 2026 Mar · PMID 41863814
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Hereditary thrombocytosis (HT) is a rare cause of elevated platelet counts in children, most commonly resulting from germline variants in or . We report the first description of bone marrow morphology in a pediatric pat...Hereditary thrombocytosis (HT) is a rare cause of elevated platelet counts in children, most commonly resulting from germline variants in or . We report the first description of bone marrow morphology in a pediatric patient with germline homozygous Baltimore (K39N) variant, a functional polymorphism resulting in HT. The patient had persistent thrombocytosis from infancy without bleeding or thrombotic complications. Bone marrow biopsy demonstrated mild hypocellularity, increased megakaryocytes forming small clusters, and megakaryocytic atypia partially overlapping with the morphologic features of myeloproliferative neoplasms (MPN). However, a somatic cytogenetic or molecular abnormality was not identified and it was determined that the thrombocytosis and bone marrow morphology were driven by the homozygous germline MPL Baltimore variant. Literature review found reports of bone marrow morphology in HT showing varying degrees of megakaryocytic proliferation and atypia with differences seen between specific germline variants. Cases with germline P106L variant have similar morphology as this homozygous Baltimore case. While cases of germline S550N are nearly identical to MPN with more severe megakaryocytic atypia and frequent development of marrow fibrosis. This case underscores the importance of considering HT in children with unexplained thrombocytosis and highlights the diagnostic pitfall of misclassifying HT as MPN.
Castaneda C, Gulliver J, Furuya K
… +4 more, Cook S, Castro E, Bockoven C, Ranganathan S
Pediatr Dev Pathol
· 2026 Mar · PMID 41858078
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Acute liver failure in the neonate generates a broad differential diagnosis of varying etiology including inborn errors of metabolism, infections, cholestatic disorders, gestational alloimmune liver disease (GALD), alpha...Acute liver failure in the neonate generates a broad differential diagnosis of varying etiology including inborn errors of metabolism, infections, cholestatic disorders, gestational alloimmune liver disease (GALD), alpha-1 antitrypsin deficiency, total parenteral nutrition-related injury, malignancy, and others. We present a case of a neonate born at 39 weeks' gestational age who presented on day 5 of life with coxsackievirus (part of the enterovirus family) encephalitis and COVID-19 infection and was subsequently found to be in acute liver failure (INR 1.7 up to 2.8 [not correctable with parenteral vitamin K], ammonia 87 umol/L up to 142 umol/L, AST 1864 IU/L, ALT 535 IU/L) with increasing alpha-fetoprotein. Evaluation for possible liver transplantation included an abdominal MRI, which showed a 2.4 × 1.7 × 2.1 cm round mass-like lesion in segment 2 of the liver, raising a differential diagnosis which included hepatoblastoma. This lesion and the background liver were biopsied. A nonspecific hepatitic pattern of injury was identified within the lesion and the background liver showed nodular post-necrotic changes with collapse of lobular architecture. While clinical case reports exist of acute hepatitis in neonates with COVID-19 alone and coxsackievirus alone, the role dual infection may play in causing severe liver injury is unique to our case and provides territory for continued investigation.
Pediatr Dev Pathol
· 2026 Feb · PMID 41731920
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Glomerulocystic renal disease has numerous etiologies, including mutations. In addition to cysts, morphologic renal findings in a setting of mutations include cystic renal dysplasia, solitary functioning kidney, horses...Glomerulocystic renal disease has numerous etiologies, including mutations. In addition to cysts, morphologic renal findings in a setting of mutations include cystic renal dysplasia, solitary functioning kidney, horseshoe kidney, and oligomeganephronia. Embryonal hyperplasia resembling nephrogenic rests has been reported in rare cases of glomerulocystic disease, but none have been genetically characterized. We report a case of bilateral glomerulocystic kidney disease (GCKD) showing extensive embryonal hyperplasia in a setting of germline mutation with progressive renal failure. Explant showed numerous epithelial proliferations throughout the intervening stroma. GCKD may be seen in a setting of mutation; however, the additional finding of extensive embryonal hyperplasia in a case with a known mutation has never been reported. Reports of similar embryonal hyperplasia, associated with either cystic kidney disease or other disease processes, appear to represent a heterogeneous population of presentations and etiologies, though there is sufficient evidence to suggest that this is a finding, that is, recurrently associated with cystic kidney diseases. The underlying pathobiology of embryonal hyperplasia and the neoplastic potential in this setting is unknown. We report this case to highlight a novel combination of morphologic and genetic findings in GCKD and to raise awareness of this rare finding.
INTRODUCTION: Anterior cutaneous nerve entrapment syndrome (ACNES) is an underdiagnosed, but common, cause of abdominal pain in children. It is unknown if the involved nerves are normal or are pathologic and should be di...INTRODUCTION: Anterior cutaneous nerve entrapment syndrome (ACNES) is an underdiagnosed, but common, cause of abdominal pain in children. It is unknown if the involved nerves are normal or are pathologic and should be divided or released and retained. We present the pathology findings of resected nerves in children with ACNES. METHODS: Operative reports, pathology reports, and clinical notes of consecutive patients who underwent anterior neurectomy from December 2011 to September 2023 were reviewed. RESULTS: One hundred and three pathology specimens from 78 patients were evaluated. Twenty-nine of the 103 specimens were from re-operative cases. Of the 103 pathology specimens, 71 (69%) had pathologic findings in the form of: myxomatous change (49, 69%), myelin vacuolar degeneration (22, 31%), perineural fibrosis (15, 21%), traumatic neuroma-like changes (2, 3%), and possible axonal injury (1, 1%). Four specimens (4%) did not have an identifiable nerve. CONCLUSION: The majority of nerve specimens from patients with ACNES were found to have changes consistent with chronic nerve damage distal to the location of presumed entrapment. Resection of these cutaneous nerves, rather than release and retention, seems prudent. LEVEL OF EVIDENCE: III.
OBJECTIVES: The significance of granulomas has still not been clarified in pediatric onset Crohn's disease (CD). The aim of this study was to investigate the phenotype and clinical course in CD patients with granuloma in...OBJECTIVES: The significance of granulomas has still not been clarified in pediatric onset Crohn's disease (CD). The aim of this study was to investigate the phenotype and clinical course in CD patients with granuloma in a comprehensive cohort. MATERIALS AND METHODS: Histopathological findings of 317 endoscopic procedures of 81 pediatric CD patients were retrospectively analyzed. The phenotype of the patients and long-term follow-up data were compared in patients with and without granuloma. RESULTS: At diagnosis, granuloma was detected in at least 1 biopsy in 39.5% of the patients. Patients with granuloma had significantly higher rate of ileocolonic disease, upper gastrointestinal involvement (68.7% vs 36.7%) and moderate-severe activity at diagnosis compared to patients without granuloma. In multivariate analysis, the presence of granulomas was associated with an increased risk of exacerbation (HR = 1.52; 95% CI: 0.83-2.75; > .05). Patients with granuloma experienced earlier exacerbation and developed fistulizing perianal disease more frequently ( = .02) and significantly earlier ( = .002) than patients without granulomas. CONCLUSIONS: Our results suggest that granulomas were associated with a distinct phenotype characterized by extensive involvement. Considering the clinical course, it is thought that granulomas may be a predictor of aggressive disease course and potential modifier of treatment strategy.
OBJECTIVE: Placental abnormalities are frequently observed in congenital heart disease (CHD) pregnancies, yet detailed histopathological evaluations are limited. This study investigated placental vascular lesions in CHD...OBJECTIVE: Placental abnormalities are frequently observed in congenital heart disease (CHD) pregnancies, yet detailed histopathological evaluations are limited. This study investigated placental vascular lesions in CHD cases, with comparisons between cyanotic and non-cyanotic subtypes. METHODS: Term singleton pregnancies with prenatally diagnosed moderate-to-severe CHD were compared to gestational age-matched controls. Placentas were assessed using standardized histopathological criteria, and CHD cases were stratified based on cyanosis. RESULTS: Among 60 placentas analyzed (40 CHD and 20 control), fetal vascular malperfusion (FVM) was significantly more frequent in the CHD group ( = .003). Other lesions, including maternal vascular malperfusion and inflammation-related findings, showed no statistically significant differences. In subgroup analysis, no clear differences emerged between cyanotic and non-cyanotic groups. CONCLUSION: CHD is strongly associated with placental FVM, indicating a possible fetal circulatory disturbance. While histological patterns were similar across CHD subtypes, the presence of FVM may provide important insights for neonatal risk assessment and management.
Congenital eruption cysts manifest in neonates when the dental follicle separates from the crown of an erupting tooth coronal to the alveolar ridge. Clinical diagnosis can be challenging as it can present clinically simi...Congenital eruption cysts manifest in neonates when the dental follicle separates from the crown of an erupting tooth coronal to the alveolar ridge. Clinical diagnosis can be challenging as it can present clinically similar to congenital epulis and other benign newborn pathologies. They can occasionally cause difficulty with feeding and latching, which can inhibit the newborn's early development. Here we present a 26-hour-old twin male infant who was evaluated for a dome-shaped nodule on the mandibular alveolar ridge. Surgical excision was performed due to difficulty in latching and feeding, and histopathological analysis revealed a congenital eruption cyst. To our knowledge, this is the first case report of a congenital eruption cyst, listing the histopathological features. A thorough literature review and a list of differential diagnoses are also discussed.
Atypical teratoid rhabdoid tumor (AT/RT) of the brain is a highly malignant (CNS WHO grade 4) embryonal neoplasm. Majority of AT/RTs occur in the posterior fossa although supratentorial examples may also be observed. Pat...Atypical teratoid rhabdoid tumor (AT/RT) of the brain is a highly malignant (CNS WHO grade 4) embryonal neoplasm. Majority of AT/RTs occur in the posterior fossa although supratentorial examples may also be observed. Pathologically, the tumor typically consists of cells with rhabdoid morphology that are immunoreactive for synaptophysin, EMA, and variably for GFAP. Diagnosis is typically confirmed by observing loss of INI-1 or BRG-1 expression from the nucleus of the tumor cells. Little is known regarding the embryogenesis of AT/RT. We therefore present here a case of supratentorial AT/RT in a 3-year-old male who presented with fatigue, irritability, left facial drop, left sided weakness of arm and leg, headaches, and vomiting. Neuroimaging revealed a large tumor involving the basal ganglia and foramen of Monro. Neuropathologic examination of the resected tumor revealed morphologic, immunohistochemical, and molecular evidence of an AT/RT (Group 1, SHH subtype). The tumor cells additionally exhibited immunoreactivity for TTF-1 (also known as NKX2.1), which has been reported to be expressed in GABAergic precursor cells in the medial ganglionic eminence. This example may provide at least a small insight into embryonic origins of supratentorial AT/RT.
BK polyomavirus-associated carcinoma of the kidney or bladder following cardiac or pulmonary transplantation has been reported in only 7 individuals, all but 1 being adults. We now report 2 additional pediatric patients,...BK polyomavirus-associated carcinoma of the kidney or bladder following cardiac or pulmonary transplantation has been reported in only 7 individuals, all but 1 being adults. We now report 2 additional pediatric patients, the first having received a lung transplant at the age of 21 months and developing a renal cell carcinoma at 14 years, and the second receiving a heart transplant at 20 months and developing a bladder urothelial carcinoma at 21 years.
Transaldolase deficiency is a rare autosomal recessive disease caused by biallelic mutations in the TALDO1 gene. This disorder is characterized by multisystem involvement, including liver disease. Here, we present 2 sibl...Transaldolase deficiency is a rare autosomal recessive disease caused by biallelic mutations in the TALDO1 gene. This disorder is characterized by multisystem involvement, including liver disease. Here, we present 2 siblings with transaldolase deficiency and a novel homozygous mutation in the TALDO1 gene. The index case was presented with hepatosplenomegaly and elevated transaminases in infancy. The 11-year-old sibling, who was diagnosed through family screening, also had chronic liver disease with fibrotic changes, despite initially normal liver function tests. Both patients exhibited additional findings, including dysmorphic facial features, hypergonadotropic hypogonadism, proteinuria, and skeletal anomalies such as scoliosis. Liver biopsies revealed periportal and bridging fibrosis without necroinflammatory activity or malignant transformation. In the second case, a 6 mm T2-hyperintense nodular lesion detected on MRI prompted close monitoring for hepatocellular carcinoma. This report highlights the phenotypic variability of TALDO deficiency, the potential for progressive liver damage in asymptomatic patients, and the importance of liver biopsy and imaging in surveillance. Early diagnosis using genetic testing and family screening facilitates the timely management of complications. Given the multisystem nature of the disorder, multidisciplinary follow-up is essential.
Rosai-Dorfman Disease (RDD) is an uncommon histiocytic disorder that can affect lymph nodes and/or extranodal sites. It is marked by the accumulation of abnormal histiocytes that demonstrate emperipolesis-the active, non...Rosai-Dorfman Disease (RDD) is an uncommon histiocytic disorder that can affect lymph nodes and/or extranodal sites. It is marked by the accumulation of abnormal histiocytes that demonstrate emperipolesis-the active, non-destructive engulfment of other leukocytes. RDD exhibits considerable variability in clinical presentation, pathology, genetics, treatment response, and patient outcomes. In this report, we describe 2 rare cases of RDD that underwent sarcomatous transformation and harbored mutations, both of which demonstrated poor responses to multiple lines of therapy. Additionally, we review 3 other similar cases from the literature.
Sex cord-stromal tumours (SCSTs) in children are rare gonadal neoplasms exhibiting differentiation towards sex cord stromal elements. This case series explores paediatric SCSTs, presenting clinical, gross, histologic, an...Sex cord-stromal tumours (SCSTs) in children are rare gonadal neoplasms exhibiting differentiation towards sex cord stromal elements. This case series explores paediatric SCSTs, presenting clinical, gross, histologic, and immunohistochemical findings, with a focus on limited information available about these tumours in African children. This retrospective study includes 9 cases of ovarian and testicular SCSTs (8 female and 1 male) in patients below 16 years of age. Female patients presented with various SCST subtypes, including juvenile granulosa cell tumours (JGCTs), fibroma, and mixed tumours. Precocious puberty was a common presentation. The male patient had a Leydig cell tumour. Tumour sizes varied, with the smallest in the testis and the largest in a 3-year-old girl. Histologically, most cases exhibited characteristic features of their respective subtypes. Paediatric SCSTs are rare but important considerations in children with gonadal masses. Their incidence in African children is largely unknown. JGCTs are the most prevalent ovarian subtype. Leydig cell tumours are rare in children and can present with virilisation. Mixed SCST-germ cell tumours, though extremely rare, warrant careful consideration and immunohistochemistry for accurate diagnosis.
Talman M, Yenamandra AK, Akkari Y
… +4 more, Tsuchiya K, Borinstein SC, Lopez-Hisijos N, Smith BN
Pediatr Dev Pathol
· 2026 · PMID 41574496
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B-lymphoblastic leukemia/lymphoma (B-ALL) is the most prevalent childhood malignancy, with improved survival rates attributed to advances in diagnosis and treatment. Herein, we present a case of B-ALL in a 6-year-old fem...B-lymphoblastic leukemia/lymphoma (B-ALL) is the most prevalent childhood malignancy, with improved survival rates attributed to advances in diagnosis and treatment. Herein, we present a case of B-ALL in a 6-year-old female who presented with clinical symptoms of leukemia, including weight loss, fever, and lymphadenopathy. Molecular and cytogenetics study revealed a t(1;22) resulting in an fusion. This case highlights diagnostic and prognostic implications of this recently recognized distinct entity.
Childhood interstitial lung diseases (chILDs) are rare respiratory conditions with significant mortality rates in neonates. They can be misdiagnosed as the symptoms overlap with other, more common neonatal diseases. Sinc...Childhood interstitial lung diseases (chILDs) are rare respiratory conditions with significant mortality rates in neonates. They can be misdiagnosed as the symptoms overlap with other, more common neonatal diseases. Since chILD can be a manifestation of the underlying syndrome, suggestive physical findings, genetic testing, and practitioners' notion can contribute to better recognition, as in our patient with confirmed Chitayat syndrome. A male preterm infant born at 34 weeks of gestation showed signs of progressive respiratory distress from birth with lung hyperinflation and ground glass opacities on chest X-ray, requiring progressive respiratory support: initially non-invasive, then invasive ventilation and surfactant administration within the first hour of life. Physical examination revealed craniofacial disproportion, low-set ears, brachydactyly of the index fingers with ulnar deviation, hallux valgus, hypotonia, and hyporeflexia. Congenital heart defects, cystic fibrosis, and primary ciliary dyskinesia were excluded. Open lung biopsy demonstrated focally dilated alveoli and thickened septa. Sanger sequencing revealed a recurrent missense variant c.266A>G p.(Tyr89Cys) in the gene. A tracheotomy was performed and despite gradual improvement with occasional respiratory support, he died at the age of 1 year and 5 months of a respiratory infection.
Pediatr Dev Pathol
· 2026 Jan · PMID 41567014
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Pleuropulmonary blastoma and hepatoblastoma are 2 well-recognized embryonal tumors of the thorax and liver respectively occurring in children. The simultaneous presentation of 2 or more pediatric embryonal tumors in the...Pleuropulmonary blastoma and hepatoblastoma are 2 well-recognized embryonal tumors of the thorax and liver respectively occurring in children. The simultaneous presentation of 2 or more pediatric embryonal tumors in the same patient is extremely rare. Specifically, cases of concomitant pleuropulmonary blastoma and hepatoblastoma in the same patient are extremely rare with only a single clinical case report published thus far. We report a case of a 25-month-old boy presenting with concomitant pleuropulmonary blastoma and hepatoblastoma, and describe the clinical, imaging, and histopathological findings. We additionally describe the underlying alterations in both tumors. This is the first case described in Vietnam and only the second such case reported globally.