Lymphoma versus thymoma: A diagnostic challenge.

T-cell acute lymphoblastic lymphoma is a common hematological malignancy of childhood. It can involve the bone marrow, blood, or tissues like the thymus, lymph nodes as well as extra-nodal sites. Two aspects of the disease make early diagnosis critical - the clinically aggressive nature of the neoplasm, and availability of effective chemotherapy against the disease. Diagnosis is largely based on clinical suspicion and confirmation by histopathological examination of the affected tissue. However, biopsy results may not always be helpful in establishing the diagnosis. We describe the case of an 18-year old patient presenting with fever and an anterior mediastinal mass suspected to have a T-cell lymphoma where an initial biopsy from the mass had features of a thymoma. The patient was kept in close follow up for 2 months when there was a recurrence of symptoms and a repeat bone marrow evaluation revealed a T-cell lymphoma.