Cutaneous findings in hairy cell leukemia.

Hairy cell leukemia is a distinctive clinicopathologic entity that is histologically characterized by infiltration of the spleen, bone marrow, and blood by uniform mononuclear cells--"hairy cells." We reviewed the prevalent cutaneous findings, specific and nonspecific, in 113 cases of hairy cell leukemia. Only one patient had specific lesions (skin infiltration by leukemic cells). Nonspecific cutaneous findings included recurrent infections, ecchymoses, petechiae, pallor, drug reactions and reactions to transfusions, and nonherpetic ulcerations. Although leukemic infiltration of the skin in hairy cell leukemia is rare, cutaneous histopathologic features may be diagnostic, particularly when cytomorphologic examination is coupled with staining of a fresh specimen with tartrate-resistant acid phosphatase. Cutaneous and extracutaneous infections, often extensive and with opportunistic organisms, were the most common nonspecific findings and demonstrated severely deficient immunologic responsiveness. Associated malignant diseases, cutaneous and extracutaneous, were few in number and are of uncertain significance.