Granulocytic sarcoma of the thymus in a nonleukaemic patient

Abstract

We report a case of granulocytic sarcoma arising from the thymus in a 17-year-old nonleukaemic patient. The patient presented with an anterior mediastinal tumour and underwent surgical resection. Histological examination showed a diffuse infiltrate of immature round cells in the thymus. Tumour cells were diffusely peroxidase positive, but naphthol AS-D chloroacetate esterase negative. Immunohistochemical staining revealed expression of CD34 and terminal deoxynucleotidyl transferase (TdT), but not of CD13 and CD33. Ultrastructurally, electron-dense or medium-density granules were present in the cytoplasm. Four months after successful autogenic bone marrow transplantation, pleural and pericardial fluid contained tumour cells with azurophilic granules, which expressed CD13 and CD33, but not CD34 and TdT. The patient died of the disease 18 months after clinical manifestation, but still without developing leukaemia. The granulocytic sarcoma in the present case may have originated from myeloid precursors in the thymus and remained within the extramedullary site despite the differentiation into a more committed myeloid lineage at the relapse.

Spontaneous mediastinal myeloid sarcoma in a common marmoset (Callithrix jacchus) and review of the veterinary literature

“…In humans, gross lesions can occur at any site in the body, but a recent literature review revealed that the mediastinum was the most common extramedullary site of myeloid sarcoma . Similar to the presentation seen in this marmoset, myeloid sarcoma has been noted in the thymus in the absence of circulating leukemic cells …”

“…20 Similar to the presentation seen in this marmoset, myeloid sarcoma has been noted in the thymus in the absence of circulating leukemic cells. 21…”

Precursor B lymphoblastic leukemia 32 months after local therapy for a primary extramedullary myeloid cell tumor

“…Only articles with adequate information about clinical presentation, diagnosis, therapy, and follow‐up were included in this study. By these criteria, the combination of the key words “chloroma,” “granulocytic sarcoma,” “myelosarcoma,” or “extramedullary myeloid cell tumor” with “child” or “pediatric” (paediatric) and review of the relevant references identified 45 patients in 39 publications 7,18–56. Patients with EMT who progressed to AML within 30 days after diagnosis to AML, as reported in 52 papers, did not fulfill the criteria for pEMT of Byrd et al 4 and were excluded.…”