Background: Rhabdomyosarcoma (RMS), is the most common soft tissue sarcoma of mesenchymal origin in children. Most of the patients presented with tumour mass. Unusual clinical presentation of the disease in an adult presented with low back pain and bicytopenia (anemia and thrombocytopenia).
Case report: A 67 year old lady with known case of diabetes mellitus, hypertension and chronic kidney disease presented with lower back pain and giddiness. On further questioning, noted patient had history of bicytopenia for 5 years. Physical examination revealed no significant abnormal findings. Full blood count gave hemoglobin of 8.4g/dL, WBC of 6.60 × 109/L and platelet count of 62 × 109/l. Peripheral blood smear showed anemia and thrombocytopenia. A bone marrow fine needle aspiration was hemodiluted. However there were 18% large abnormal mononuclear cells that were block positivity on Periodic Schiff stain. The immunophenotyping detected a population of cell with CD45 negative, dim CD1, dim HLA-DR and CD56 positive. The trephine biopsy showed the marrow areas are diffusely infiltrated by poorly differentiated large mononuclear cells with hyperchromatic nuclei. After the immunohistochemical stain done a diagnosis of bone marrow infiltration by high-grade sarcoma was made. Patient was further investigated for primary site tumour. Biopsy polyp at the body of stomatch and fundal polyp in keeping with poorly differentiated malignancy, favoring Alveolar Rhabdomyosarcoma.
Discussion and conclusion: Here we highlight a case with a rare presentation of Alveolar Rhabdomyosarcoma infiltrated bone marrow. Correlation with relevant investigations (immunophenotyping, cytochemistry, immunohistochemical stains, cytogenetic and molecular) are helpful in diagnostic work-up as the cells may mimic a hematopoietic cells.