Sarcomatoid Morphology in Pediatric Langerhans Cell Neoplasm Does Not Always Predict Aggressive Clinical Course

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 <i>OSBPL9::BRAF</i> fusion and BRAF V600E mutation.