Mycosis fungoides presenting as pigmented purpuric eruption.

A case of pigmented purpuric eruptions evolving to mycosis fungoides during the 4-year follow-up period is described. Clinical manifestation was characterized by petechial lesions with irregular shaped, diffusely pigmented plaques partly sharing morphological similarities with chronic pigmented purpura. Histologically, lymphocytes infiltrated around the capillaries of the superficial dermis with extravasated erythrocytes as well as into the epidermis to form Pautrier microabscesses. Whereas CD4+ cells were observed in the epidermis and upper dermis, CD8+ cells tended to be distributed around the capillaries. Notably, the Rumpel-Leede test revealed extensive punctuate purpura limited to the lesional skin. The aggregation response of platelets was not impaired. Either CD4+ tumor lymphocytes or CD8+ reactive lymphocytes appeared to induce capillary damage resulting in the formation of petechial lesions. Pigmented purpuric eruptions, such as atypical chronic pigmented purpura, is thus an important initial clinical manifestation of mycosis fungoides.