Author(s): Usha Amirtham1, Shankaranand Siddappa Bharatnur2, Shanthi Velusamy3, Mangalagowri Mayanna4, Prasanna Kumari5, Lakshmaiah Chinnagiriyappa Kuntegowdanahalli6, Rekha Vijaykumar7

Myeloid sarcoma (MS) is defined as “a tumour mass consisting of myeloid blasts with or without maturation, occurring at an anatomical site other than bone marrow”. It rarely arises as the only lesion, referred to as primary myeloid sarcoma. Secondary myeloid sarcomas precede or develop concomitantly with acute myeloid leukaemia (AML), myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN) or MDS/MPN. MS developing in a known patient of AML is considered as relapse irrespective of blood and bone marrow findings. This study retrospectively analyses the clinicopathological, morphological and immunohistochemical profiles along with available data on cytogenetics and followup of 25 patients diagnosed as myeloid sarcoma in a regional cancer centre in South India.
All cases diagnosed histopathologically as myeloid sarcoma between 2006 and 2015 were retrieved from the archives of the department of pathology. The clinicopathological profile of these cases was reviewed, including age, sex, site of involvement and accompanying haematological findings. Immunohistochemical and cytogenetic findings were noted along with laboratory data and median survival time.
Of the 25 cases studied, 18 patients were male and 7 patients were female. The age ranged from 14 months to 65 years. The commonest site of involvement was lymph node followed by bone, skin and soft tissue. Twenty cases represented primary MS and the remaining five cases were secondary myeloid sarcomas. Of the latter, four cases were associated with AML and one with chronic myeloid leukaemia (CML). One case of primary lesion in the radius subsequently developed another lesion in calcaneum after 3 years. Trisomy 8 was the commonest cytogenetic abnormality seen. Two patients of the series are alive and on treatment whereas 7 patients died within a year of diagnosis and the remaining were lost to followup.
Myeloid sarcoma is a rare disease with a higher incidence in males. It was seen more commonly as an isolated lesion in our study involving the lymph nodes. It requires early diagnosis and appropriate management including bone marrow transplantation, considering the high mortality.

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