Primary myelofibrosis relapsed with duodenal myeloid sarcoma after allogeneic stem cell transplantation

Extramedullary blastic transformation of primary myelofibrosis in the form of disseminated myeloid sarcoma: a case report and review of the literature

Splenomegaly is a key clinical manifestation of myelofibrosis, and splenectomy is currently indicated in patients with drug refractory, symptomatic splenomegaly or with the aim of improving refractory cytopenias. Transformation to acute myeloid leukemia occurs in up to 20% of patients with myelofibrosis, while cases of myeloid sarcoma have been reported very unfrequently. In this manuscript, we report the case of a 60-year-old man with a history of primary myelofibrosis who underwent splenectomy because of drug-refractory massive splenomegaly, systemic symptoms and anemia. At the opening of the peritoneal cavity, the spleen resulted massively enlarged and tenaciously entrapped by a pervasive neoplastic-like tissue. The extensive involvement of the abdomen fatally complicated the surgical procedure. At postmortem examination, the spleen showed a diffuse infiltration of immature cells that were also found in the peritoneum, bowel, liver, lungs and myocardium. After immunohistochemical, cytogenetic, flow cytometric and molecular characterization of neoplastic population, a diagnosis of disseminated myeloid sarcoma of the spleen was made. This case report highlights a very unusual case of myeloid sarcoma originating from the spleen in a patient with myelofibrosis who had no evidence of bone marrow or peripheral blood involvement by leukemic cells. Molecular characterization showed that leukemic cells originated from the founding clone of the chronic phase. The sarcoma could not be suspected based on clinical findings and was diagnosed only at the time of surgical procedure and autopsy. This case suggests that leukemic transformation of myelofibrosis can originate outside the bone marrow and, presumably rarely, present as a granulocytic sarcoma.

Autopsy case of primary myelofibrosis in which myeloid sarcoma was the initial manifestation of tumor progression

Myeloid sarcoma (MyS) is defined as an extramedullary tumor-forming neoplasm consisting of immature myeloid cells with/without maturation. We experienced a case involving a 68-year-old Japanese male patient who had been followed-up for four years with a diagnosis of chronic idiopathic myelofibrosis/primary myelofibrosis (PMF) and noticed a painful mass in his left axilla. A wedge biopsy characterized the lesion as MyS that displayed megakaryoblastic/megakaryocytic differentiation. As his complete blood count included a few myeloid blasts (1% of WBC) and a bone marrow biopsy detected fibrosis without evidence of acute myelogenous leukemia (AML), a diagnosis of extramedullary blastic transformation of PMF was made, which was confirmed later by V617F mutation in Janus kinase-2 in both initial bone marrow biopsy and axillary tumor biopsy specimens. The patient died of pneumonia eight months after developing the axillary tumor. At autopsy, multiple MyS masses were detected in his soft tissue, but his bone marrow only contained fibrosis. Although MyS rarely develops before the leukemic transformation of PMF, no evidence of AML could be found in the patient's bone marrow at any point during the course of his disease. Thus, it is possible that the blasts in his peripheral blood were derived from the remaining MyS. Furthermore, the present case indicates that extramedullary blastic transformation, which is occasionally seen in CML, can also occur in PMF. Therefore, it is important to recognize that there is a wide variation in the pathogeneses of MyS and PMF.