Pediatric Interdigitating Dendritic Cell Sarcoma and High-Grade Myxoinflammatory Fibroblastic Sarcoma: Case Reports

Abstract

Rare soft tissue sarcomas such as interdigitating dendritic cell sarcoma (IDCS) and high-grade myxoinflammatory fibroblastic sarcoma (MIFS) are diagnostically challenging due to their rarity and overlapping histopathologic features with other neoplasms. We report two unusual cases diagnosed at the Histopathology Department, King Fahad Specialty Hospital, Tabuk, KSA. The first involved a 2-year-old male presenting with a maxillary sinus mass, an unprecedented location for pediatric IDCS. To our knowledge, this is the first reported pediatric IDCS in the maxillary sinus. Histology revealed spindle to ovoid tumor cells with variable nuclear atypia arranged in fascicles and storiform patterns. Immunohistochemistry showed positivity for S100, CD68, CD63, EGFR, and cyclin D1, confirming the diagnosis with the latter two staining results suggesting potential activation of the MAPK/ERK signaling pathway. The second case involved a 70-year-old woman with a high-grade MIFS of the lower limb. Histopathology demonstrated aggressive features, including necrosis, infiltrative growth, and high mitotic activity, with tumor cells positive for CD10 and D2-40. The IDCS patient followed an aggressive course and patient died before surgical intervention, while the MIFS patient received wide local excision with close follow-up. Both cases underscore the importance of thorough clinicopathologic correlation and immunohistochemical analysis for accurate diagnosis. Identifying rare sarcomas in unusual locations or age groups, utilizing specific immunohistochemical markers to distinguish them from histologically similar tumors, and applying precise grading are all critical for guiding prognosis and ensuring appropriate management.

Keywords: Interdigitating Dendritic Cell Sarcoma, Myxoinflammatory fibroblastic sarcoma, Pediatric.