Part 2: Peripheral T-Cell Non-Hodgkin Lymphoma
Eric D. Jacobsen, MD
Dr. Jacobsen is an instructor in Medicine, Harvard Medical School; Attending Physician, Dana-Farber Cancer Institute, Boston, MA.
A 35-year-old man presents with a 3-week history of cough. Two weeks ago he completed a 5-day course of azithromycin without improvement in his symptoms. A subsequent chest radiograph showed a widened mediastinum consistent with mediastinal lymphadenopathy. A chest computed tomography (CT) scan confirmed the presence of an 8-cm mediastinal mass. The patient underwent a mediastinoscopy and biopsy, pathology from which revealed a population of lymphocytes that were negative for CD10, CD19, CD20, TdT, Pax 5, and CD15 but were positive for CD30. Which of the following is the most important immunohistochemical test to help establish the diagnosis?