CD30-positive primary cutaneous anaplastic large cell lymphoma with coexistent pseudocarcinomatous hyperplasia.

CD30-positive primary cutaneous anaplastic large cell lymphoma (C-ALCL) is an indolent type of cutaneous lymphoma with favourable clinical prognosis. Pseudocarcinomatous hyperplasia (PCH) is a rare benign epithelial condition that can resemble invasive squamous cell carcinoma both clinically and histopathologically. PCH predominantly occurs in CD30-positive lymphoproliferative disorders. We report a 75-year-old woman with PCH in a multifocal C-ALCL located on the scalp and right retroauricular area, which rapidly responded to treatment with psoralen ultraviolet A photochemotherapy. Comprehensive virological analyses for potential oncogenic viruses, including Epstein-Barr virus, human herpesvirus-8, human papillomaviruses, the recently discovered cutavirus and nine different human polyomaviruses, were negative.