Interdigitating Dendritic Cell Sarcoma: A Rare Diagnostic Challenge.

Interdigitating dendritic cell sarcoma (IDCS) is a rare malignancy with a poor prognosis, and currently, there lacks a standardized treatment protocol. IDCS can be challenging diagnostically given its immunophenotypic overlap with other malignancies such as melanoma. We describe a 52-year-old woman presenting with a left cervical mass. Following workup and MDT discussion, she underwent a unilateral modified radical neck dissection and superficial parotidectomy. On histopathological examination, despite some morphological and immunohistochemical overlap with melanoma, IDCS was confidently diagnosed. There have been few cases of IDCS in the head and neck published since the most recent pooled analysis. This case adds to the current literature, highlights unique diagnostic findings, and explores its overlap with melanoma. More data are required regarding treatment outcomes and follow-up for cases of IDCS. Increased reporting such as this case will facilitate future analyses to guide management of this rare malignancy.