Metastatic thymoma involving the bone marrow.

Although relatively rare, thymomas can be involved in a considerable variety of clinical presentations. Clinicians should be mindful of the breadth of associations with other diseases, including autoimmune disorders and many secondary nonthymic malignancies. For the pathologist, knowledge of the extremely varied histopathologic presentation of thymoma is vital to formulate a proper differential, workup, and diagnosis. The presented case illustrates the finding of very rare metastatic thymoma involvement of bone marrow, identified during evaluation for pancytopenia. The history of prior prostate cancer and an uncharacterized pancreatic lesion, as well as the familial presentation, also suggests a possible underlying hereditary syndrome.