ABSTRACT
Specific and nonspecific skin lesions are associated with many hematopoietic malignancies. Specific skin lesions result from direct infiltration of the dermis or subcutaneous fat by malignant leukemic cells. Nonspecific lesions are much more common and may be due to marrow failure that is the result of replacement of hematopoietic tissue by neoplastic cells. Petechiae, purpura, and ecchymoses may occur as a result of severe thrombocytopenia. The immunocompromised state of patients with leukemia is often associated with an enhanced susceptibility to bacterial, fungal, and viral infections. Specific skin lesions may be the initial clue to the presence of an underlying hematologic malignancy. Although the majority of specific lesions occur in the setting of established hematologic malignancy, the skin infiltrates may present concomitantly with systemic leukemia, or in some cases, precede the development of systemic disease (1-3). Patients with suspicious clinical lesions should have a skin biopsy performed. The diagnosis of specific skin infiltrates is based on the recognition of the preponderant cell type and pattern of infiltration in the skin and on correlation with clinical and hematologic findings. In the large majority of cases, an objective diagnosis of specific cutaneous infiltrate in patients with leukemia can be made based on distinctive clinicopathologic features. Immunohistochemical studies are helpful for distinguishing lymphoid and nonlymphoid cells, identifying subsets of these cells based on their immunophenotype. Improvements in cell identification by molecular biologic techniques are also essential for the increased precision in the diagnosis and classification of leukemias. Dermatologists must approach cutaneous leukemic infiltrates by being aware of the morphological diversity expressed by these neoplastic proliferations and of the difficulty in differentiating leukemic skin infiltrates from those of lymphomas, nonhematopoietic neoplasms, and numerous nonspecific skin lesions.
