Introduction:

Chronic myelomonocytic leukemia is a clonal disorder, in which the change affects the normal development of monocytes, affecting 3/100,000 people after age 65 in the United States.

Clinical case:

80-year-old male, with onset of the disease 60 days ago, presenting skin lesions of the nodule-papular-erythematous type, some confluent, with well-defined edges, some purpuric in appearance, disseminated to extremities, respecting face, palms and soles; with 2-cm hepatomegaly and splenomegaly 3 cm below the costal margin; the white formula showed: monocytes 27%, platelets 40,000/mcL. Upon examination of blood smear: metamyelocytes 2%; myelocytes 1%; cytoplasmic vacuolization of monocytes, diffuse basophilia and 1% of normoblasts. Immunophenotypic examination showed: increase of SS (granularity) in the monocyte population, decrease in the expression of CD4 and HLA-DR, overexpression of CD123 and CD16, in addition to aberrant expression of CD56 in 32.8% of total leukocytes; the skin biopsy showed: skin with infiltration by malignant neoplastic cells arranged in nests or laces, with positive myeloperoxidase immunohistochemical marker.

Conclusion:

Diagnosis of chronic myelomonocytic leukemia with dermic infiltration was established.