[Parapsoriasis en plaque suspected of progression to mycosis fungoides associated with extranodal malignant B cell lymphoma of the cheek].

A 59-year-old female, clinically diagnosed as having parapsoriasis en plaque for ten years, was referred on June 1991 to the Department of Oral Surgery in the Dental School of showa University with a complaint of painless swelling of the left malar area. The swelling was found to have been caused by a tumor. Since the excised tumor was suspected to be a malignant lymphoma, she was admitted to our hospital. The specimen was subsequently confirmed to be a malignant lymphoma of the diffuse large cell type according to the LSG classification, and was immunologically confirmed to be a B cell lymphoma. In addition, the excised skin was suspected of incipient mycosis fungoides. She was classified as having stage IE disease according to her bone marrow biopsy and other examinations. she was treated with combination of chemotherapy (CHOP) and radiation therapy. This subject was interesting because her tumor probably resulted from a parapsoriasis en plaque skin lesion.