Myeloid sarcoma of the small intestine in nonleukemic patients - A report of three cases with review of literature.

Abstract

Background: Granulocytic sarcoma (GS) or myeloid sarcoma (MS) is a tumor of hematopoietic stem cell origin composed of myeloblasts or immature myeloid cells presenting as tumor masses in an extramedullary site. The tumor can affect any site of the body but are commonly seen in the skin, bone and lymph node. It may develop de novo or concurrently with acute myeloid leukemia (AML), myeloproliferative disorder (MPD) or myelodysplastic syndrome (MDS). MS may precede AML by months or years or present as an initial manifestation of relapse in a previously treated AML in remission. On light microscopic examination, based on histological features cases of MS are frequently erroneously diagnosed, more so in non-leukaemic patients, as non-Hodgkin lymphoma (NHL) or undifferentiated carcinoma. Immunophenotyping is needed for a diagnosis of MS. A variety of chromosomal abnormalities are reported; particularly t(8;21)(q22;q22), which is regarded as a recurrent aberration in MS. Only a few cases of MS of the small intestine in non-leukaemic patients, defined by the absence of a history of leukemia, myelodysplastic syndrome (MDS), or myeloproliferative neoplasm along with a negative bone marrow biopsy, are described in literature. Treatment strategies are still not well defined.

Methods: We analyse and describe 3 cases of patients with MS involving the intestine and describe the histological diagnostic pointers, clinicopathologic and immunophenotypic features.

Results: Granulocytic sarcoma has definite well recognisable diagnostic features. The characteristic features include: tumor cells arranged in sheets and in occasional infiltrating singles; absence of necrosis; starry-sky appearance; scattered eosinophils & promyelocytes; tumor cells negative for CD3, CD20, while being positive for CD45 (patchy) and CD19.

Conclusions: Granulocytic sarcoma is a rare disease and a high index of suspicion is needed for making a correct diagnosis. Judicious use of immunohistochemistry helps in coming to a diagnosis. We propose a diagnostic algorithm for making a diagnosis of granulocytic sarcoma.