Myeloid sarcoma as the presenting symptom of chronic myelogenous leukemia blast crisis

Myeloid sarcoma is an extramedullary tumor composed of immature myeloid cells that efface the underlying tissue architecture. It is usually associated with acute myelogenous leukemia, but can be associated with myeloproliferative neoplasms, myelodysplastic disorders, or myeloproliferative/ myelodysplastic syndromes. If it is unrecognized, appropriate chemotherapy may be delayed and survival jeopardized. We present a case of a myeloid sarcoma presenting in an otherwise asymptomatic patient who ultimately was found to have chronic myelogenous leukemia, presenting in blast crisis. We also review the distinct clinical and pathologic features of myeloid sarcoma, as well as treatment of the disease.