Leukocyte common antigen-negative, aggressive cutaneous anaplastic large cell lymphoma with prominent pseudocarcinomatous hyperplasia.

Patients with anaplastic large cell lymphoma (ALCL) often present with tumor-mediated skin changes, including pseudocarcinomatous hyperplasia (PCH), acquired ichthyosis, and tissue neutrophilia. We report a 58-year-old male patient with leukocyte common antigen (LCA)-negative, null cell-type ALCL associated with marked PCH mimicking undifferentiated squamous cell carcinoma. Although lymphocyte markers were lacking, the CD30 expression and the clonal rearrangement of the T-cell receptor gamma gene confirmed the diagnosis of ALCL. The patient had an aggressive clinical course, in which the tumor cells metastasized to the regional lymph nodes a few months after surgical removal of the primary lesion, and skin nodules recurred on the face despite intensive polychemotherapy, followed by autologous peripheral blood stem cell transplantation. The diagnosis of ALCL was delayed in our case because of the prominent PCH, the lack of LCA, and the unusually rapid progression of the tumor.