Differential Diagnosis of Isolated Myeloid Sarcoma: A Case Report and Review of the Literature

Myeloid sarcoma (MS) is a rare disease entity identified as a variety of manifestations defined by the occurrence of extramedullary myeloid cell masses with or without bone marrow involvement. This case describes an unusual presentation of isolated MS in a 60-year-old otherwise healthy male, who initially presented to his primary care physician with vague abdominal pain. After extensive workup including three omental biopsies, umbilical core biopsy, and inguinal lymph node biopsy, he was ultimately diagnosed with isolated MS with extensive extramedullary tumor burden. Despite advanced extramedullary disease, peripheral cell counts were normal and bilateral bone marrow biopsies unremarkable with normal cellular lineages, morphology, and cytogenetics. The patient underwent induction chemotherapy and is now greater than 100 days post myeloablative unrelated donor marrow transplantation with no evidence of disease recurrence and 100% donor status with full chimerism. This case demonstrates that making a prompt diagnosis with rapid initiation of treatment in myeloid sarcoma can be challenging due to its varied clinical presentation, cytomorphology, cytochemistry, and cytogenetic overlap with other lymphoid malignancies. Once a diagnosis of MS has been made, moving quickly to induction therapy is important. Several studies have shown that improved overall survival is attained when MS is treated as acute myeloid leukemia and increased survival is noted for patients undergoing bone marrow transplantation. Further prospective studies are needed to elucidate the many remaining questions in regards to the natural history, prognosis, and optimal treatment strategies for this deadly disease.