Spindle Cell Mucoepidermoid Carcinoma of the Palatine Tonsil With CRTC1-MAML2 Fusion Transcript: Report of a Rare Case in a 17-Year-Old Boy and a Review of the Literature.

Mucoepidermoid carcinoma (MEC) with a predominant spindle cell composition occurring in the palatine tonsil is exceedingly rare. We present a case of a 17-year-old boy with an uncommon spindle cell variant of MEC arising in the palatine tonsil. Histologically, the tumor showed a solid, noncystic architecture and was composed of a predominant population of bland spindle to fusiform cells arranged in organoid nests with interspersed goblet cells and focal areas of ductular structures. Reverse transcriptase polymerase chain reaction and fluorescence in situ hybridization (FISH) revealed the presence of a t(11;19) CRTC1-MAML2 gene fusion in this rare variant of MEC. This is the first case report of a spindle cell MEC of the palatine tonsil, with molecular genetic confirmation. It illustrates the importance of awareness and recognition of this uncommon histological variant of MEC, which will help establish appropriate treatment and prognostication.