[A Case of Myeloid Sarcoma That Primarily Developed in the Spleen].

We report a case of myeloid sarcoma(MS)that primarily developed in the spleen. The patient was a 60s man with a chief complainant of low-grade fever following a dental implant. Although he underwent intensive antibiotic treatment, including levofloxacin, meropenem, and vancomycin, no significant decline in fever was observed. Abdominal contrast-enhanced CT revealed an LDA occupying the majority of his spleen, which was diagnosed as a splenic abscess. Although a CT-guided biopsy and drainage for the spleen were considered, a puncture of the spleen was not performed due to the substantial concern of bleeding. Subsequently, a splenectomy was performed and HE staining revealed mitosis of tumor cells and massive necrosis. Immunohistochemical analysis revealed that the tumor cells were positive for myeloperoxidase, CD43, CD45, and CD68. Finally, the splenic LDA was diagnosed as MS instead of a splenic abscess. He was treated with systemic chemotherapy. MS primarily develops in the spleen is quite rare: we found only 2 case reports of this disease. The prognosis of MS is poor due to the complications of AML. Accordingly, MS should be considered as a differential diagnosis for accurate diagnosis and treatment of splenic LDA.