AITL : Skin Lesions
Cutaneous involvement is seen in up to 50% of cases of angioimmunoblastic T-cell lymphoma (AITL). Skin lesions can consist of pruritic maculopapular rash on trunk and extremities mimicking viral eruption or a drug hypersensitivity reaction. Other forms include papulovesicular lesions, plaques, nodules, erythroderma, urticaria, erosions, petechiae and purpura. Skin biopsies show superficial or superficial and deep perivascular or periadnexal infiltrates of pleomorphic atypical lymphoid cells. Usually, there is associated vascular hyperplasia with prominence of endothelial cells. Some cases show leukocytoclastic vasculitis or granulomatous inflammation. The tumor cells are CD4+ and express CD2, CD3, and CD5. Markers of follicular T-helper cells (CD10, CXCL13, PD1, and BCL6) are expressed in at least some of the cells. The expanded follicular dendritic cell networks adjacent to high endothelial venules can be highlighted by CD21, CD23, or CD35. CD20 is positive in scattered B-cell blasts. These cells are also positive for EBV by in-situ hybridization. T-cell receptor genes are clonally rearranged in skin specimens in a small proportion of cases. However, the diagnosis of AITL cannot confidently be made on skin biopsy alone. The distinction of AITL from reactive cutaneous infiltrates may be extremely difficult. Correlation with clinical features and lymph node pathology is essential. Image courtesy of: Woo Cheal Cho, MD (@DrAldehyde); used with permission.