Abstract

CRTC1::TRIM11 cutaneous tumor (CTCT) is a rare skin tumor of uncertain differentiation. In the 48 reported cases, CTCT has been generally described as indolent, with only 3 cases showing regional or distant metastasis. Herein, we present the 1st case of CTCT with ulceration. Our case is the 2nd tumor arising in acral skin and the 4th case with regional lymph node metastasis. A 75-year-old male with a 5-month history of toe ulceration underwent a shave biopsy which showed an ulcerated dermal nodular neoplasm that was immunoreactive for SOX10 and S100, negative for Melan-A, and initially diagnosed as melanoma. Upon further 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 HMB45 and PRAME. Next generation sequencing identified a 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 an in-transit metastasis. The SLN revealed multifocal metastasis in a subcapsular distribution. The patient was started on adjuvant nivolumab and is recurrence-free at 4 months after amputation. In summary, we present the 1st case of CTCT with ulceration and SLN metastasis. While initial reports of CTCT suggested an indolent nature, we provide additional evidence that a subset of these neoplasms has the potential for aggressive behaviour. The optimal surgical and medical treatments are unknown.