A systematic morphological analysis of cutaneous infiltrates in
acute myelogenous leukemia and
myelodysplastic syndrome revealed that in many cases the infiltrating cells have a different phenotype from those in the bone marrow. This study sought to answer two questions: (a) How wide is the range of cytological features and immunoreactivity of the cutaneous infiltrates and what danger is there of misinterpretation? (b) What are the possible causes of the wide spectrum of differentiation of the cells infiltrating the skin? Skin biopsy specimens from 16 patients with
myelogenous leukemia or
myelodysplastic syndrome were investigated. The diagnosis was
acute myelomonocytic leukemia (M4, according to the French-American-British/FAB system of classification of acute
leukemias) in eight cases,
acute monocytic leukemia (M5) in four cases, aleukemic
leukemia cutis as a recurrence of M2
leukemia after treatment in one case, and
myelodysplastic syndrome in three cases, including one case of myelodysplasia with an excess of bone marrow blasts (
RAEB-T) and two cases of
chronic myelomonocytic leukemia, one of which presented as aleukemic
leukemia cutis. Reactivity with the macrophage-associated
antibodies anti-CD68, Ki-M1p, and anti-
lysozyme was the most consistent. However, the
naphthol AS-D chloroacetate esterase reaction and staining with DAKO-M1, Ki-My2p, anti-
neutrophil elastase, and anti-CD34 were found to be of little value for identifying the cutaneous infiltrate as myelogenous. Some
antibodies (e.g., anti-
S100 protein and MB2) even produced staining in a few cases that could have led to a mistaken diagnosis of histiocytic
neoplasm or
malignant lymphoma.(ABSTRACT TRUNCATED AT 250 WORDS)