Unicentric Castleman disease masquerading as a gluteal mass: A diagnostic challenge.

Castleman disease, a rare lymphoproliferative disorder characterized by non-neoplastic lymph node enlargement, typically presents as nodal involvement, while extranodal manifestations are uncommon. We present a unique case of unicentric Castleman disease localized to the gluteal region in a 27-year-old female. Initially mistaken for a neurogenic or vascular tumour, fine needle aspiration cytology (FNAC) revealed a polymorphous population of lymphoid cells with numerous traversing capillaries suggestive of reactive hyperplasia, possibly Castleman disease, which was later confirmed by histopathology. This case highlights the diagnostic challenges posed by rare extranodal presentations of Castleman disease and underscores the importance of interdisciplinary collaboration in accurate diagnosis and management.