Diagnosis of anaplastic lymphoma kinase-negative anaplastic large cell lymphoma on pleural fluid cytology.

ALK-negative anaplastic large cell lymphoma (ALCL) is an aggressive non-Hodgkin T-cell lymphoma. Compared to ALK-positive ALCL, patients with ALK-negative ALCL typically are older, present with nodal disease, and have lower survival rates. We report a unique presentation of ALK-negative ALCL in a pleural fluid. Cell block preparation enabled both confirmation of the diagnosis via immunohistochemical staining and gene rearrangement testing for prognostic information.