Minimally differentiated acute myeloid leukaemia revealed by specific cutaneous lesions.

Minimally differentiated acute myeloid leukaemia (AML-MO) is a poorly differentiated type of acute myeloid leukaemia. Its myeloid differentiation can only be demonstrated by the immunohistochemical or ultrastructural finding of cytoplasmic myeloperoxidase in bone marrow blasts and/or by the immunohistochemical expression of at least one lineage-specific myeloid antigen, with no reactivity for lymphoid antigens. We describe a man with a cutaneous nodular eruption that represented the first clinical manifestation of AML-MO. Histological examination showed extensive proliferation of blasts with scant basophilic cytoplasm. Immunohistochemically, these expressed neither myeloid nor lymphoid-specific antigens, whereas they were focally positive for CD45. The diagnosis of AML-MO was confirmed by immunophenotypic analysis of a bone marrow smear. A complete remission was achieved following parenteral steroid therapy. The disease relapsed some months later, and the patient died within a few weeks.