Mediastinal Myeloid Sarcoma is a rare entity. Here we present a case of a 28-year-old gentleman, who first presented with a mediastinal mass and was clinically considered lymphoblastic lymphoma. He was diagnosed initially as having T lymphoblastic lymphoma on a mediastinal trucut biopsy. After one month patient was diagnosed with Acute myeloid leukemia on peripheral smear and bone marrow examination and was confirmed with the help of flow cytometry. The biopsy slides from the mediastinal mass were reviewed and based on the smear findings additional immunohistochemical markers were added and diagnosed as Myeloid Sarcoma. Keywords: Myeloid sarcoma, Mediastinum, Acute myeloid leukemia

BACKGROUND Pancytopenia is an important clinico-haematological entity encountered in our daily clinical practice. There are varying clinical patterns, treatment modalities and outcomes for pancytopenia. The severity of pancytopenia and the underlying pathology determine the management and prognosis of the patient. Hence, the evaluation of the various causes of pancytopenia could aid in planning the diagnostic and therapeutic approach in patients with pancytopenia. Megaloblastic anaemia is one of the major causes of pancytopenia in India. The objectives are to identify the various causes of pancytopenia, to describe the clinical and haematological parameters in pancytopenia. MATERIALS AND METHODS A descriptive study on 80 cases was conducted to describe the various causes of pancytopenia in the peripheral blood, bone marrow aspirate and trephine biopsy samples of pancytopenia patients received in the Department of Pathology, Government Medical College, Kottayam during a period of 12 months (June 2016-May 2017). RESULTS Among the 80 cases of pancytopenia studied, common causes were megaloblastic anaemia (18 cases, 23%) and acute lymphoblastic leukaemia (9 cases, 11%). Majority of the patients had a hypercellular bone marrow (70%). CONCLUSION Most common cause of pancytopenia was megaloblastic anaemia followed by acute leukaemia.