T-Lymphoblastic Leukemia/Lymphoma and Thymoma: A Case Report and Review of the Literature of a Rare Association.

The co-occurrence of thymoma and T-lymphoblastic lymphoma/leukemia is an extremely rare but previously reported association that poses a diagnostic and therapeutic challenge. We describe a 67-year-old patient with long-standing untreated B1 thymoma that presented with constitutional symptoms and a painless soft tissue mass on the right chest wall. Pathological analysis of the biopsy from the mass demonstrated T-lymphoblastic leukemia/lymphoma. The patient went through a complicated course, was refractory to several lines of therapy, and eventually underwent allogeneic hematopoietic stem cell transplantation in complete remission from a matched related donor. The association between thymoma and malignant neoplasms has been described in the literature, most notably with colorectal adenocarcinoma and thyroid cancer. Thymoma-associated leukemia is, however, extremely unusual, with limited reports in the literature. Distinguishing between thymoma and leukemia can be challenging and often requires meticulous diagnostic efforts. For patients with a past history of thymoma, awareness of this particular association should be bared in mind to allow earlier diagnosis and therapy.