A Case Report of Paraneoplastic Pemphigus Associated With Retroperitoneal Inflammatory Myofibroblastic Tumor.

Paraneoplastic pemphigus (PNP) is an autoimmune bullous disease associated with underlying neoplasms, both malignant and benign. The most constant clinical presentation of PNP is the presence of intractable stomatitis. Herein we present a 25-year-old male with a 3-month history of refractory stomatitis especially involving the lips and widespread vesiculobullous eruption on his trunk and extremities. The diagnosis of PNP was confirmed based on histological and serological results. Investigation for the underlying neoplasm revealed a retroperitoneal tumorous mass which was biopsied and diagnosed as the inflammatory myofibroblastic tumor (IMT). The tumor was surgically excised, and different treatment regimens were used to treat the mucocutaneous lesions. Skin lesions responded favorably to treatment, but oral stomatitis still persists which is the case in most PNP patients. This combination of PNP and IMT has rarely been reported in the literature. Treatment started with corticosteroid and rituximab then tumor excised.