Ulcerated CRTC1::TRIM11 cutaneous tumor with metastases

CRTC1::TRIM11 cutaneous tumor (CTCT) is a rare skin tumor of uncertain differentiation. In the 49 reported cases, only four cases showed regional or distant metastasis, but follow‐up remains limited. Herein, we present a case of metastatic CTCT with ulceration, a histological feature that has not been previously described. A 75‐year‐old male with a 2‐month history of toe ulceration underwent a shave biopsy, which showed a dermal nodular neoplasm that was immunoreactive for SOX10 and S100, negative for Melan‐A, and was initially diagnosed as melanoma. Upon pathology review at our institution, the tumor was composed of intersecting fascicles and nests of epithelioid and spindle cells. Additional immunohistochemistry revealed immunoreactivity of the tumor for MiTF and NTRK and negativity for HMB‐45 and PRAME. Next‐generation sequencing identified CRTC1::TRIM11 fusion, leading to a revised diagnosis of CTCT. The patient proceeded to a toe amputation and sentinel lymph node (SLN) biopsy 5 months after the shave biopsy. The amputation showed residual CTCT and a focus on lymphovascular invasion. The SLN revealed multifocal subcapsular metastases. The patient was started on adjuvant nivolumab and showed biopsy‐proven recurrence in the right inguinal lymph nodes and imaging findings suspicious for pulmonary metastases 8 months after the excision. In summary, we present a case of CTCT with ulceration and lymphovascular invasion. We also provide additional evidence that a subset of CTCT behaves aggressively. The optimal surgical and medical treatments are unknown.