Educational Case: Gallstones, Cholelithiasis, and Cholecystitis.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

Myeloid Sarcoma of the Bladder in the Setting of Refractory Anemia with Excess Blasts-2 (RAEB-2).

Myeloid sarcoma is an extramedullary tumor consisting of immature hematopoietic cells of granulocytic or monocytic differentiation. While rare, it can be seen in a variety of clinical settings and is most commonly associated with acute myeloid leukemia (AML), myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). We present a rare case of myeloid sarcoma occurring in the bladder of a 56 year old male. Myeloid sarcoma may be difficult to recognize due to its rarity and clinical and morphologic similarity to many other conditions; however, swift diagnosis is necessary as it is considered equivalent to AML. Prognostic indicators for myeloid sarcoma have not been well established, but survival may be improved by undergoing chemotherapy designed to treat AML.