Abstract
Purpose
CRTC1::TRIM11 cutaneous melanocytic tumors are a recently described uncommon entity almost exclusively reported as arising in the skin with fewer than 70 described cases and no dedicated reports of tumors arising in the sinonasal cavity (SNC). We identified 3 cases arising in the SNC with similar morphology and immunophenotype, all harboring CRTC1::TRIM11 fusion. We present the clinical, histological, immunophenotype, and molecular profile of these tumors and compare our tumors with those previously reported in the literature and provide practical guidance for evaluating tumors in the SNC with undifferentiated, neuroendocrine, or melanocytic phenotype.
Methods
Formalin-fixed, paraffin embedded tissue sections of the patients’ tumors were examined and compared with routinely stained sections and by immunohistochemistry. Whole exome/whole transcriptome sequencing revealing CRTC1::TRIM11 fusions in each case was performed at Caris® Life Sciences.
Results
The patients were 34, 48, and 69 years of age, 2 females and 1 male. All tumors originated in the nasal cavity and hard palate. Original diagnoses were S100-negative granular cell tumor, poorly differentiated carcinoma and mucosal melanoma. All tumors demonstrated highly cellular proliferations of round/ovoid cells arranged in vague organoid clusters. Individual cells had moderate eosinophilic granular cytoplasm and round nuclei containing dispersed and granular chromatin with visible nucleoli resembling neuroendocrine tumors. The neural markers synaptophysin and chromogranin were negative, however, tumors expressed PGP9.5 and NCAM in 2 cases. All cases expressed SOX10 in a diffuse fashion but negative for S100, Melan-A, HMB-45. CRTC1::TRIM11 fusion was detected in all cases.
Conclusions
This recently described CRTC1::TRIM11 fusion-driven tumor almost exclusively described in cutaneous sites, hence the current designation as cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMTCT), can arise in the nasal cavity and should be considered in the differential diagnoses of aggressive tumors with similar morphologies in the SNC that include mucosal melanoma, sinonasal undifferentiated carcinoma, and neuroectodermal and neuroendocrine carcinomas.