Dermal melanocytic tumor with CRTC1‐TRIM11 fusion: Report of two additional cases with review of the literature of an emerging entity

Abstract

“Cutaneous melanocytic tumor with CRTC1‐TRIM11 fusion” (CMTCT) is a newly described, potentially novel entity that typically presents as a dermal nodule on the head and neck, extremities, and trunk of adults. Histopathologically, it is reported as a nodular or multinodular tumor composed of epithelioid and spindle cells that are variably immunoreactive for S100‐protein, SOX10, and MITF along with more specific melanocytic markers such as MelanA and HMB45. With only 11 cases reported in the English literature so far, the neoplasm appears to behave in a relatively indolent fashion. Nevertheless, in one case, local recurrence and synchronous distant metastasis were evident after 13 years. Additional cases with longer follow‐up are essential to determine the neoplasm's biologic behavior with more accuracy. Herein, two cases of CMTCT, one arising on the lower back of a 65‐year‐old female and the other on the arm of a 33‐year‐old female in addition to a comprehensive literature review are reported.

Cutaneous Melanocytic Tumor with CRTC1::TRIM11 Fusion: Review of the Literature of a Potentially Novel Entity

“…The immunohistochemical profile of a CMTCT case are displayed in Figure 2A-D. Immunohistochemical features of CMTCT include consistent diffuse SOX10 and MITF immunoreaction [1][2][3][4][5]. MelanA and HMB-45 expression may be focal or patchy and, in some instances, completely absent.…”

“…So far, 13 cases of CMTCT have been reported [ 1 , 2 , 3 , 4 , 5 ], eight on the extremities, three on the head and neck, and two on the lower back. Sizes ranged from 0.4 to 5.1 cm in greatest diameter (median 1 cm), and patient age ranged from 11–82 years (median 33 years).…”

“…Cytologically, it exhibits pale to eosinophilic cytoplasm, mild to severe pleomorphism with mild to moderate nuclear atypia, and prominent nucleoli and nuclear pseudoinclusions. All reported cases [ 1 , 2 , 3 , 4 , 5 ] displayed mitotic activity, ranging from 1 to 12 mitoses/10HPF. Areas of necrosis have also been identified in three cases so far [ 4 ].…”

“…Cellier et al [ 1 ] first reported five cases in 2018, and described it as a relatively well-circumscribed neoplasm composed of atypical spindle and epithelioid cells immunoreactive for melanocytic markers, such as SOX10, MITF, and S100-protein; it was initially termed “cutaneous melanocytoma with CRTC1::TRIM11 fusion”. Since then, eight more cases sharing the same morphologic, immunohistochemical and molecular phenotype have been added to the literature [ 2 , 3 , 4 , 5 ]. The histopathologic differential diagnosis includes cutaneous clear cell sarcoma, primary dermal and metastatic melanoma, atypical blue nevus, Spitz tumor, myoepithelial tumor, epithelioid schwannoma, malignant peripheral nerve sheath tumor (MPNST), and paraganglioma-like dermal melanocytic tumor.…”

Recent advances in the diagnosis, classification and molecular pathogenesis of cutaneous mesenchymal neoplasms

“…Melanocytoma with CRTC1 :: TRIM11 fusion exhibits strong and diffuse expression of SOX10, S100 protein and MITF, with less consistent positivity for HMB45 and melan A. Most of the 13 cases reported in the literature to date have demonstrated an indolent course, albeit with relatively short clinical follow‐up 126–130 . However, there is a single reported tumour that occurred in the arm of a 31‐year‐old woman and gave rise to local recurrence and metastases to the axilla and lung after an interval of 13 years 127 .…”