A Case of a CRTC1::TRIM11 Cutaneous Tumor With Venous and Lymphatic Invasion and Lymph Node Metastasis.

A CRTC1::TRIM11 cutaneous tumor (CTCT) represents a novel and rare entity in dermatological oncology. We report a case of a 29-year-old Vietnamese woman who presented with a nodule on her right thigh and underwent surgical resection. Initially, a presumptive diagnosis of a fibrohistiocytic tumor was made based on histological features and immunohistochemical results, which were negative for S-100 and positive for CD68. However, further consultation revealed additional immunohistochemical findings: diffuse positivity for S-100, SOX10, and TRIM11, as well as focal positivity for HMB45 and MelanA. Fluorescence in situ hybridization showed no EWSR1 gene rearrangement. Consequently, a final diagnosis of CTCT was established. Postoperative PET/CT scans suggested metastasis in the right inguinal lymph node, which was confirmed by excisional biopsy. This case demonstrated partially invasive proliferation, venous and lymphatic invasion in the primary lesion, and lymph node metastasis, providing histological evidence of malignancy. Surgical resection is considered the primary treatment approach, but standardized protocols for adjuvant therapy have yet to be established. Targeted therapies against the CRTC1::TRIM11 fusion gene may offer novel and more effective treatment options, and further research is warranted.