IgG4-related sclerosing disease clinically mimicking oral squamous cell carcinoma.

IgG4-related sclerosing disease is a distinct clinicopathologic entity known to involve the maxillofacial region, particularly the salivary, lacrimal, and pituitary glands. We report a case with lesions involving the tongue and palatine tonsil with associated skin lesions. A 45-year-old female patient presented with a history of soreness, dysphagia, and an asymptomatic rash involving the upper trunk. The initial clinical diagnosis of her oral lesions was squamous cell carcinoma. The diagnosis of an IgG4-related lesion was confirmed by histologic examination of the oral and skin lesions as well as confirmation of raised serum IgG4 levels. Tapering systemic corticosteroid therapy resulted in complete resolution of the lesions. This is the first report of IgG4-related sclerosing disease presenting as concurrent oral and skin lesions, with the oral lesion clinically resembling oral squamous cell carcinoma. Such lesions present a diagnostic challenge, but the outcome is very favorable.