Granulocytic sarcoma. Cranial and breast involvement.

The term granulocytic sarcoma designates an infrequent solid tumor composed of aggregates of immature granulocytic precursors in extramedullary sites. The lesion generally occurs either during the natural course of acute myelogenous leukemia or after a remission has been achieved; however, it may rarely represent the initial manifestation of the disease. We present radiologic features of cranial and breast involvement of granulocytic sarcoma in a 13-year-old female with acute myelogenous leukemia. The cranial lesion appeared nearly isointense with cortical gray matter on T1- and T2-weighted magnetic resonance (MR) images, and enhanced homogeneously after the injection of gadolinium. MRI showed a well-delineated lobulated mass in the left breast, which had a heterogeneous hyperintense signal and remarkable contrast enhancement.