First case report of tongue squamous cell carcinoma in a neurofibromatosis type 1 patient and review of pathogenesis of carcinoma in neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1), also known as von Recklinghausen's disease, is a type of genodermatoses having an autosomal dominant inheritance pattern and is recently considered as a RASopathy. Such patients are very much prone to develop mesenchymal tumors. However, carcinomas are quite rare in NF1 patients. This case study is the first case of oral squamous cell carcinoma (SCC) in tongue of an NF1 patient. A 35-year-old male reported to the Department of Oral Pathology in a tertiary care center with a chief complain of a painful ulcer on tongue for last 1 month. For confirmation of diagnosis of NF1, the "Diagnostic Criteria for Neurofibromatosis Type 1" was followed. Biopsied specimen of the tongue lesion was examined under microscope and histopathological features were suggestive of infiltrating SCC. Immunohistochemistry with Pan CK and beta-catenin was positive. RASopathy, WNT-beta-catenin pathway alteration, heat shock factor 1 production, and miRNA activity are investigated to explain the pathogenesis of malignancies in NF1 patients. In this first case of tongue SCC, we have found out the altered WNT-beta-catenin pathway.