A case of Ki-1 positive anaplastic large cell lymphoma transformed from mycosis fungoides.

A case of cutaneous Ki-1 positive anaplastic large cell lymphoma which developed in the plaque stage of mycosis fungoides was described. A 73-year-old woman who had suffered from pruritic scaly eruptions over her entire body for more than two decades was admitted because of an ulcerated tumor measuring 45 x 55 x 15 mm and several satellite tumors on the buttock. All tumorous lesions were resected without recurrence to date. Histochemical study revealed that the tumor consisted of large anaplastic cells which were Ki-1 (CD30)-positive and LCA-negative. Some of the erythematous plaques contained LCA-positive, small-sized atypical lymphocytes. In other plaques which developed two years later, there were large Ki-1-positive atypical cells. In the specimens obtained from the tumor and the plaque, the same pattern of T-cell receptor gene rearrangements was detected. These findings indicate that both Ki-1 positive anaplastic cells in the tumor and atypical lymphoid cells in the plaques were derived from the same T cell clone.