Malignant lymphoma presenting as pseudoepitheliomatous hyperplasia. A report of two cases.

The authors report two patients with cutaneous and submucosal non-Hodgkin's lymphoma of probable T-cell phenotype that presented as florid pseudoepitheliomatous hyperplasia. The first patient presented with lesions of the nasopharynx and nose that were originally misdiagnosed as invasive squamous cell carcinoma, causing a delay in appropriate treatment. In the second patient, skin lesions of the thigh and arm closely mimicked squamous cell carcinoma. To prevent misdiagnosis of these lesions, pathologists should adhere to strict morphologic criteria for the diagnosis of squamous cell carcinoma and be aware that malignant lymphoma may be associated with overlying pseudoepitheliomatous hyperplasia. The pathogenesis of pseudoepitheliomatous hyperplasia arising in association with neoplasms is still not clear, but it may be related to the production of cellular growth factors by the inciting tumor.