Clinical Features:

• An aggressive lymphoproliferative disorder caused by infection with the virus HTLV-1, which is endemic in Japan, the Caribbean, South America and central Africa
• The lifeteme risk of developing ATLL among individuals infected with HTLV-1 is 2.5%.
• Four clinical forms: acute, chronic, smoldering and lymphoma
• The acute form presents with high-grade leukemia, marrow involvement, skin lesions, generalized lymphadenopathy ane hepatosplenomegaly.
• Characteristic of all forms is hypercalcemia, extreme thirst and circulating CD25 (IL-2 receptor; HTLV-1 infects CD4+ T-cells by way of this receptor)
• Diagnosis is based upon clinical features with serologic demonstration of anti-HTLV-1 antibodies.
• Cutaneous manifestations are variable, and can include generalized erythroderma, a maculopapular rash, nodules, plaques and bullous lesions.

Histologic Features:

• Dense lymphoid infiltrate throughout the dermis and subcutaneous fat
• The infiltrate is often most dense around blood vessels and skin appendages.
• Exocytosis into the epidermis, with or without Pautrier's microabscesses, often occurs.
• The neoplastic lymphocytes range in size from small to large and have markedly convoluted nuclei.
• There is often marked dermal edema.
• Vasculitis with red blood cell extravasation is often seen.
• Circulating leukemic cells have large convoluted nuclei said to resemble a flower with petals ("flower cells")
• Immunophenotypically, the cells are helper T-cells (CD3+, CD4+, CD5+, CD8+), usually with loss of CD7 and characteristic expression of CD25.