Lymphomatoid papulosis followed by Ki-1 positive anaplastic large cell lymphoma: proliferation of a common T-cell clone.

We report a case of lymphomatoid papulosis (LyP) followed by Ki-1 positive anaplastic large cell lymphoma (LCL). A 33-year-old man developed subcutaneous nodules in the left inguinal region and the left thigh after a seven-year-history of self-healing papulonecrotic lesions of LyP. Histological and immunohistochemical examination of the subcutaneous nodules revealed LCL. DNA was isolated from a nodule of the initial stage of LyP in 1988, a subcutaneous nodule of LCL in 1993, and a papule of LyP in 1993 which appeared after chemotherapy for LCL. T cell receptor gene rearrangement analysis demonstrated an identical rearranged pattern in all the three specimens, indicating that a common T cell clone proliferated throughout the course in both the LyP and LCL lesions.