Expanding Our Knowledge of Molecular Pathogenesis in Histiocytoses: Solitary Soft Tissue Histiocytomas in Children With a Novel CLTC::SYK Fusion.

The histiocytoses comprise a histopathologically and clinically diverse group of disorders bearing recurrent genomic alterations, commonly involving the BRAF gene and mitogen-activated protein kinase pathway. In the current study, a novel CLTC :: SYK fusion in 3 cases of a histopathologically distinct histiocytic neoplasm arising as solitary soft tissue lesions in children identified by next-generation sequencing and fluorescence in situ hybridization is described. Morphologically, all 3 neoplasms were composed of sheets of cells with round-oval nuclei and vacuolated eosinophilic cytoplasm but, in contrast to classic juvenile xanthogranuloma (JXG), Touton giant cells were absent. A separate cohort of classic JXG cases subsequently profiled by fluorescence in situ hybridization were negative for the presence of a CLTC::SYK fusion suggesting that CLTC::SYK fusion-positive histiocytoma is genetically and histologically distinct from JXG. We postulate that the CLTC::SYK fusion leads to aberrant activation of the SYK kinase, which is involved in variable pathways, including mitogen-activated protein kinase. The identification of a novel CLTC::SYK fusion may pave the way for the development of targeted therapeutic options for aggressive disease.

Secretory-IgA binding to intestinal microbiota attenuates inflammatory reactions as the intestinal barrier of preterm infants matures.

Previous work has shown that Secretory-IgA (SIgA) binding to the intestinal microbiota is variable and may regulate host inflammatory bowel responses. Nevertheless, the impact of the SIgA functional binding to the microbiota remains largely unknown in preterm infants whose immature epithelial barriers make them particularly susceptible to inflammation. Here, we investigated SIgA binding to intestinal microbiota isolated from stools of preterm infants <33 weeks gestation with various levels of intestinal permeability. We found that SIgA binding to intestinal microbiota attenuates inflammatory reactions in preterm infants. We also observed a significant correlation between SIgA affinity to the microbiota and the infant's intestinal barrier maturation. Still, SIgA affinity was not associated with developing host defenses, such as the production of mucus and inflammatory calprotectin protein, but it depended on the microbiota shifts as the intestinal barrier matures. In conclusion, we reported an association between the SIgA functional binding to the microbiota and the maturity of the preterm infant's intestinal barrier, indicating that the pattern of SIgA coating is altered as the intestinal barrier matures.

Sentinel bowel loop as a marker for primary segmental intestinal volvulus in extreme low birth weight neonates.

Primary segmental intestinal volvulus is a rare condition that may affect neonates. This condition occurs when a loop of bowel torses around the axis of its mesentery without any other abnormality or malrotation. In the earlier stages, the diagnosis can be challenging due to the lack of specific clinical and radiographic signs. Prompt surgical management is critical as a delay in diagnosis may result in bowel loss or death. We present a series of three cases of extremely low birth weight infants with primary segmental volvulus. A sentinel bowel loop was critical in guiding each patient's surgical management as there were no other clinical markers concerning a pending intra-abdominal catastrophe. This case series suggests that a sentinel bowel loop may be a radiographic marker for primary segmental intestinal volvulus in extremely low birth weight infants.

Atypical smooth muscle tumor of the vagina--a pediatric case report and review of the literature.

Vaginal tumors in children are uncommon. This report describes the rare case of an atypical smooth muscle tumor arising from the vagina in a pediatric patient managed with tumor resection, vaginal reconstruction, and continent urinary diversion. We also discuss a review of the literature and a brief report detailing our experience with pediatric vaginal tumors.