Gingival squamous cell carcinoma masquerading as necrotizing ulcerative periodontitis.

Necrotizing ulcerative periodontitis (NUP) is a painful and debilitating condition seen mostly in an immunocompromised state. Although squamous cell carcinoma (SCC) on gingiva is not uncommon, its presentation as a benign necrotizing lesion on gingiva is rare. Such presentations may lead to delayed diagnosis and poor prognosis. This report describes a case of a 34-year-old male presenting clinically with NUP around mandibular posterior teeth. Clinical features were misleading, but the histological findings established the diagnosis of well-differentiated SCC. Immunohistochemistry also showed features of epithelial-mesenchymal transition with decreased expression of E-cadherin and increased vimentin expression showing local invasion and metastasis. The patient was referred to the oncology department for evaluation of possible metastasis and further management of carcinoma.