Myeloid Sarcoma Masquerading as Granulation Tissue: A Diagnostic Pitfall.

Myeloid sarcoma is an uncommon neoplasm, comprising an extramedullary tumorous proliferation of immature myeloid cells. Its rarity and tendency for diverse clinical presentation contribute to difficulty in timely diagnosis. This report describes a case of a painful back lump in an elderly Chinese male, which was initially diagnosed as a carbuncle. Histology on the saucerization specimen was reported as inflamed granulation tissue. Failure of expected wound healing prompted surgical debridement; microscopic examination on the subsequent specimen revealed an immature myeloid population with an increased MIB-1 proliferative index, highlighted by myeloperoxidase, lysozyme, CD117, and CD43 immunoreactivity, in keeping with myeloid sarcoma. Despite aggressive management, the patient eventually died. This report draws attention to potential pitfalls in the pathological diagnosis of this uncommon tumor and briefly summarizes its salient features.