Regression of thymoma-induced lichenoid hypersensitivity reactions of the oral mucosa following thymoma treatment: a case report.

Thymomas are neoplasms associated with paraneoplastic disorders. Severe hypersensitivity reactions involving the oral cavity may be the first sign of an undiagnosed thymoma. Oral manifestations of an underlying thymoma may present as recurrent severe painful lesions with associated significant morbidity, often not responding to standard therapeutic measures. This case report describes the treatment of a 75-year-old woman who presented with severe oral lichenoid hypersensitivity reactions secondary to an undiagnosed underlying thymoma. No substantial improvement of the oral conditions was achieved with conventional therapies (topical and systemic steroids); however, almost complete resolution of the lesions was achieved following completion of radiation therapy for the thymic neoplasm. This article is intended to serve as a resource for clinicians to understand early, rare manifestations of an undiagnosed thymoma.