Uterine NTRK-Rearranged Spindle Cell Neoplasm With Unusual Morphology-A Case Report and Literature Review

NTRK-rearranged spindle cell neoplasm is a rare lesion in the uterus (including the cervix), with more than 60 tumors reported in the literature so far. Most of them are characterized by fascicles of spindle cells in herringbone pattern with entrapment of endocervical glands. We report an additional tumor occurring in the uterine cervix of a 43-year-old Chinese woman, which demonstrated unusual morphologic features in addition to the conventional fibrosarcoma-like spindle cell proliferation. These included areas of neural-like whorls, as well as nuclear palisading that resembled a schwannoma. Focal myxoid stroma with loose clusters of rhabdoid cells was also identified. The nuclear grade was intermediate to severe and geographic necrosis was identified. Immunohistochemistry showed diffuse positivity for pan-TRK with patchy CD34 and focal S100 expression. Molecular analysis revealed the presence of TPM3::NTRK1 fusion with CDKN2A/B homozygous deletion and low mutational burden. Our case report and literature review highlight the diverse morphological appearance of this tumor. Specifically, nuclear palisading and rhabdoid cells are rarely reported in uterine NTRK-rearranged spindle cell neoplasm. As more clinical and molecular data become available, the clinicopathological features of this entity can be further characterized.