Summary

 
Background: Leukemic infiltration of the skin is a rare diagnosis. Articles and paragraphs in textbooks on the subject include only very few images of clinical lesions and photomicrographs of histopathologic features. Objectives: To present the morphologic spectrum of specific infiltration of the skin in different kinds of leukemia. Patients/Methods: Clinical and histopathologic study of 34 patients with leukemia cutis. Results: Specific infiltrates are more common in myelogenous leukemias (21 patients with AML, 3 with CML) than in lymphocytic leukemias (6 patients had CLL, 4 had ALL); they are more often exanthematic in myelogenous variants (60% versus 40%) and individual lesions in lymphocytic examples (30% versus 70%). Histopathologically, infiltrates were sparse in 17 % of the specimens, moderately dense in 51 % and dense in 32 % of the specimens. The subcutaneous fat was involved commonly. Cells were small in CLL, and larger in ALL; AML, and CML, in the latter two sometimes resembling histiocytic or plasmacytic morphology. Identification of subtypes of acute myelogenous leukemia was not possible based on infiltrates in the skin. Infiltrates, in general, were monomorphous. Mitotic figures as well as necrotic cells were more commonly encountered in myelogenous variants. A subepidermal grenz zone was spared in 61% of the cases. In 46% of the specimens cells of leukemia were found within the arrector pili muscle. Rarely, specimens showed signs of acuteness of a disease process. Conclusions: Leukemic infiltrates in the skin encompass a broad spectrum of clinical and histopathological manifestations that may at times be difficult to tell apart from inflammatory diseases of the skin. Clinicopathological correlation often assists in coming to a specific diagnosis. Further histopathologic clues to the diagnosis are presented in the article.

Sushil Pande M.D., is a dermatologist at KEM Hospital in Mumbai, India; Betina Werner is a dermatopathologist in private practice in Curitiba, Brazil; and Almut Böer is a dermatopathologist at the Dermatologikum in Hamburg. This article was reviewed by Muna Shuweiter, M.D., and Valerie Goldburt, M.D., Ph.D. . Contact corresponding author via e-mail: boer@dermatologikum.de.