Papuloerythroderma-like cutaneous involvement of a CD62L^- subclone of T-cell prolymphocytic leukemia

We report the case of an 88-year-old Japanese man with erythrodermic involvement of T-cell prolymphocytic leukemia (T-PLL). He had a history of pharyngeal diffuse large B-cell lymphoma successfully treated with polychemotherapy including cyclophosphamide and epirubicin, 6 years before the current illness. He presented with numerous reddish, coalescing, flat-topped papules on the trunk and extremities, sparing the skin folds of the abdomen, the features of which mimicked those of papuloerythroderma. Immunohistochemistry showed perivascular and epidermotropic infiltration of CD3⁺ CD4⁺ T cells in the cutaneous lesion. However, flow cytometric analysis revealed that the skin infiltrating T cells were negative for surface CD4, and that CD3⁺ CD4^- CD8^- cells made up 92% of the T-cell fraction of peripheral blood. The circulating atypical T cells had a round or oval nucleus and prominent nucleoli, and the deletion of chromosomes 6q, 13 and 17. These cytological profiles were consistent with those of T-PLL and distinct from those of Sézary cells. The same T-cell clone was detected in the cutaneous lesion and peripheral blood, but the expression of CD62L was absent in the skin infiltrates and present in the circulating cells. No specific mutation was detected in STAT3 or STAT5B. Although low-dose oral etoposide had a beneficial effect on the skin rash, a fatal crisis of marked leukocytosis (169 × 10³ /μL) occurred 19 months after the illness onset. CD62L-leukemic cells of T-PLL may infiltrate the skin to form papuloerythroderma-like cutaneous lesions.