Acute Myeloid Leukemia

Acute Myeloid Leukemia – Granulocytic Sarcoma

MR – Mid-sagittal T1 and IR and midsagittal and parasagittal post gadolinium T1 images of the lumbosacral spine demonstrate extraosseous presacral and sacral hitatus masses. Also note the massive mesenteric lymph nodes with follicular masses.

Granulocytic sarcoma, also known as chloroma or extramedullary myeloblastoma, is a rare solid tumor related to acute myeloid leukemia composed of primitive precursors of the granulocytic series of WBC that include myeloblasts, promyelocytes, and myelocytes. Granulocytic sarcomas of the bone commonly involve vertebral bodies, the sternum, orbits, cranium, sacrum, and ribs. Granulocytic sarcoma arises in bone marrow and traverses the haversian canals to reach the periosteum, resulting in bone lysis and sometimes adjacent soft-tissue masses and periostitis. The radiographic differential diagnoses are metastatic neuroblastoma, Ewing’s sarcoma, eosinophilic granuloma, and primitive neuroectodermal tumor in children. Lesions are isointense to bone marrow on both T1- and T2- weighted MR images; they enhance homogeneously after injection of contrast medium. Massive nodal enlargement in AML is seen in about 25% of cases and is often related to a monocytic predominance of the leukemia.

Guermazi A, Feger C, Rousselot P, et al. Granulocytic Sarcoma (Chloroma):Imaging Findings in Adults and Children. AJR (2002); 178:319-325.