Oral Squamous Cell Carcinoma Following Acute Methotrexate Toxicity in a Psoriasis Patient: A Causal Association or Mere Co-Incidence

Background: Methotrexate is an antimetabolite anticancer drug frequently used in the treatment of extensive chronic plaque psoriasis. Psoriasis patients on treatment with immunosuppressants have an increased risk of developing malignancies. Objective: To present a rare case of Oral Squamous Cell Carcinoma (OSCC) in a psoriasis patient postacute methotrexate toxicity. Case Report: A 47-year-old female, a known case of chronic plaque psoriasis for which she was on 15 mg/ week methotrexate therapy and accidentally consumed 15 mg for 7 consecutive days. She was successfully treated for methotrexate toxicity and 45 days later she presented with exophytic growth on the tongue. Histopathology confirmed the diagnosis of squamous cell carcinoma and the patient underwent surgical resection. Conclusion: There could be a causal association between psoriasis and OSCC in the setting of acute methotrexate toxicity, as in the present case.