Pediatric and Developmental Pathology

Social media has been recently highlighted as a unique and modern virtual force that allows for worldwide connection, collaboration, communication, and engagement between pathologists, trainees, and medical students. Much literature has been focused on the role of social media in recruitment and medical education practices of different pathology subspecialties, such as dermatopathology and hematopathology. However, current literature on pathology social media’s status and potential future roles in promoting pediatric pathology is sparse. Herein, this review intends to narrow this knowledge gap by reviewing how social media has been utilized in different pediatric subspecialties, the current use of social media in pathology, and how the future of pediatric pathology social media use may look moving forward regarding education, research, and recruitment. Specific tips and related online resources are provided.

Chronic intervillositis of unknown etiology (CIUE) is an aberrant maternal inflammatory infiltrate comprised primarily of macrophages that collect in the intervillus space and is associated with poor outcomes including recurrent pregnancy loss. An abnormal maternal Th1-type response to pregnancy may be the basis for pathogenesis of CIUE but macrophage in the maternal infiltrate of CIUE have been reported to have an anti-inflammatory M2 phenotype characterized by increased expression of CD163. This study assesses expression of CD163 in CIUE and SARS-CoV-2 placentitis, which has a similar histopathological presentation, using an automated approach to minimize observer-related variability. The data show that the maternal inflammatory infiltrate of CIUE contains a blended population of high and low CD163 expressing macrophage with a prominent bias towards an anti-inflammatory M2 phenotype when compared to normal control tissue. A similar pattern is seen in SARS-CoV-2 placentitis, suggesting pathophysiologic similarity with CIUE, although SARS-CoV-2 also appears to promote decreased CD163 expression in Hofbauer cells, which is not seen in CIUE.

We present a case of a 13-year-old patient with a distinct tumor with both granular cell and perineurial elements, located on the lower lip. The patient presented with a long-standing lip mass that was clinically felt to most likely represent a mucocele. Following surgical excision, histopathological examination revealed a well-circumscribed tumor composed of granular cells with positive S100 protein staining and spindled cells positive for EMA and GLUT-1, confirming mixed neuroectodermal and perineurial origin. This is the first case documenting a perineurial-granular cell hybrid tumor in a patient under 18 years old, and the first to be reported in the head and neck. This case expands our understanding of hybrid PNSTs, emphasizing the importance of considering diverse clinical presentations, especially in the context of rare pediatric occurrences in atypical locations.

Pediatric angiosarcoma of soft tissue, an extremely rare entity, remains poorly understood from a genetic standpoint. Herein, we present the case of a previously healthy 17-year-old girl with acute left hip pain. Subsequent magnetic resonance imaging revealed a 21.8 cm left pelvic sidewall mass with heterogeneous enhancement and multiple lung nodules. Biopsy of the tumor showed an infiltrative, hemorrhagic neoplasm composed primarily of atypical spindle to epithelioid cells. Focal vasoformative architecture was appreciated. Immunohistochemically, the tumor cells were strongly positive for CD31, ERG, and FLI-1, supporting the diagnosis of angiosarcoma. Genetic analysis identified a novel TEK::GAB2 gene fusion. TEK belongs to the angiopoietin receptor family, and its fusion with GAB2 is predicted to mediate tumorigenesis. This report expands the current knowledge on the spectrum of gene rearrangements of angiosarcoma.

Casamassima-Morton-Nance syndrome (CMNS) is a rare disorder characterized by spondylocostal dysostosis (SCD), anal atresia, and urogenital anomalies. We describe a fetus with CMNS associated with a limb-body wall defect (LBWD), the second such case in the literature. We compare the phenotypic differences with previously reported cases, including those with segmentation anomalies of the axial skeleton, body wall defects, or absent/abnormal genitalia, revealing the consistent presence of SCD in CMNS. However, as expected, a wide phenotypic spectrum emerges, providing useful observations for fetal/neonatal screening relevant to differential diagnoses. Advanced diagnostic methods using imaging and next-generation skeletal dysplasia multi-gene panels are advisable, as they enable timely, actionable, well-informed decisions for parental counseling, potential elective termination of pregnancy, and prenatal and/or postnatal care. Most reported cases do not mention the recurrence of these usually lethal anomalies.

Langerhans cell sarcoma (LCS), a rare malignant neoplasm in the general category of myeloid neoplasms characterized by overtly malignant Langerhans cells (LC) with conspicuous mitotic activity including atypical forms. Although most cases occur in adults, rare examples of LCS have been reported in children with variable clinical outcome. We present 2 childhood cases of Langerhans cell neoplasm with high grade sarcomatous features and OSBPL9::BRAF fusion and BRAF V600E mutation.

Hereditary multiple intestinal atresia (HMIA) with TTC7A mutation is caused by homozygous or compound heterozygous TTC7A gene mutation. It is characterized by multiple small and large intestinal atresias and/or stenoses. TTC7A mutation is described in some patients with inflammatory bowel disease and mild-severe forms of severe combined immunodeficiency without intestinal atresia or stenosis. We present 2 cases of intestinal atresia and documented TTC7A mutation with a novel variant. Both cases had different clinical and pathological manifestations. The first case is a male infant born at 35 weeks of gestation with failure to pass meconium. Intestinal biopsy reveals apoptotic enteropathy with villous atrophy and increased mucosal eosinophils. The second case is referred at birth for antenatally detected umbilical hernia, polyhydramnios and possible upper intestinal obstruction. The resected specimen reveals ileal atresia with partial villous atrophy, decreased number of lamina propria inflammatory cells and absence of plasma cells. In conclusion, these cases reflect an emerging TTC7A pathogenic variant with different histological manifestations and leads to characterization as immune dysregulation disorder. There is a need to differentiate TTC7A mutation associated ones from cases labeled as very early onset IBD and rule out other hereditary immunodeficiencies.

Neuronal ceroid lipofuscinosis type 2 (CLN2) results from biallelic pathogenic variants in the TPP1 gene, leading to deficient activity of the lysosomal enzyme tripeptidyl peptidase 1. We report an autopsy case of CLN2 characterized at molecular level. The patient exhibited a spectrum of neurologic symptoms including epilepsy, behavioral alterations, cognitive regression, motor impairment, and visual loss. In fundus exam, a cherry-red spot was observed. She died at 7 years old, autopsy demonstrated severe atrophy of the brain and cerebellum with neuronal loss and gliosis. Neurons were distended by autofluorescent ceroid lipofuscin of 2 types: fine granular deposits and coarse round bodies. In addition, electron microscopy study revealed characteristic curvilinear profiles. After autopsy, a germline molecular test was performed that found the c.1226 G>T variant in a homozygous state. This variant has been referenced in a single undetailed report and is classified as of uncertain significance. Our findings support that cherry-red spot can be present in CLN2 and confirm the pathogenicity of the c.1226 G>T variant. Current management of CLN2 includes enzyme replacement that requires early diagnosis, which can be facilitated by clinical delineation of the disease and appropriate classification and public reporting of TPP1 variants.

Fetal primary cardiac tumors (FPCTs) are very rare. The majority of them correspond to cardiac rhabdomyomas, followed by other benign neoplasms or hamartomas. We describe the case of a third trimester female stillborn with an incidental autopsy finding of Hamartoma of Mature Cardiac Myocytes (HMCM), a rare benign cardiac tumor previously unreported in the fetal or neonatal period. The intrauterine demise occurred at 32 + 6 weeks gestation after an uneventful pregnancy. The fetal autopsy revealed a structurally normal heart with a small subendocardial nodule just below the membranous septum. Microscopically, the nodule was well-demarcated from the surrounding penetrating bundle of the conduction axis and the adjacent left ventricular myocardium and consisted of disorganized mature cardiac myocytes in a haphazard arrangement with patchy mild interstitial fibrosis, consistent with HMCM. Awareness that HMCM can occur in the fetus is important in order to consider it among the differential diagnosis of FPCTs.