Isolated leukemia cutis as extramedullary relapse of acute myeloid leukemia

Abstract

Acute myeloid leukemia (AML) arises from clonal expansion of malignant hematopoietic precursor cells in the bone marrow. In rare instances, AML can recur with prominent extramedullary manifestations (i.e., leukemia cutis or myeloid sarcoma), either simultaneously or preceding marrow involvement, or as a sole site of primary disease relapse.

Keywords: AML; MLL gene; MLL rearrangement; acute myeloid leukemia; leukemia; leukemia cutis.

FIGURE 1

Initial diagnosis of AML and relapse following remission of AML. (A) BMB at the time of diagnosis reveals hypercellular marrow for age with markedly decreased trilineage hematopoiesis (4× magnification). (B) On higher power, the leukemic blast cells show prominent nucleoli and scant cytoplasm (40× magnification). (C) Dermatological physical exam was remarkable for a 2 cm × 1.5 cm thin pink purple plaque on her right lower back. (D) Histopathologic sections show an unremarkable epidermis with an underlying atypical infiltrate of immature hematopoietic blasts extensively involving the dermis and underlying subcutaneous adipose tissue (4× magnification). (E) On higher power, the immature blasts show enlarged nuclei with prominent nucleoli and amphophilic cytoplasm (40× magnification). (F) CD117 immunohistochemical stain shows that the majority of neoplastic cells are positive for CD117 (40× magnification). (G) Recent bone marrow biopsy shows trilineage hematopoiesis with no morphological evidence of involvement by leukemic blast cells. (4× magnification)