Primary popliteal granulocytic sarcoma: a case report and review of literature

Primary granulocytic sarcoma (PGS), also known as chloroma, is a type of malignant tumour that forms in extramedullary tissues by proliferating myeloblasts or immature granulocytes. Here, we reported a 63-year-old female case of PGS that primarily emerged in the popliteal fossa. Macroscopically, a greyish white and greyish yellow mass was observed, with 7.5 x 6 x 3 cm in size. Microscopically, the mass was cystic and necrotic tissue was present within the cyst, which was uniformly infiltrated with small- or medium-sized round cells with basophilic cytoplasm and fine chromatin. The immunohistochemical staining showed positive for MPO, LSZ and CD43. Additionally, we reviewed the relevant literature in order to improve our understanding of the disease.