Adult T-Cell Leukemia/Lymphoma With Extranodal Involvement of the Hypopharynx.

Adult T-cell leukemia/lymphoma (ATLL) with extranodal lesions in the head and neck region is rare, with only a few cases reported so far. To our knowledge, this the first case reported involving the hypopharynx. The patient in this case was a 49-year-old woman who presented to an otolaryngology clinic complaining of an abnormal sensation in the throat and difficulty in swallowing. Endoscopic examination revealed an irregular mass with a smooth surface centered on the left piriform sinus and extending to the arytenoid and post-cricoid area. Imaging studies revealed lymphadenopathy in multiple cervical lymph nodes and in the hepatoduodenal mesentery. Examination of a peripheral blood smear revealed proliferation of atypical lymphocytes including flower cells. Further history-taking revealed that both the patient and her parents were positive for human T-cell lymphotropic virus type 1 (HTLV-1) antibodies and that her sister had developed ATLL. Lymph node biopsy was performed; hematoxylin-eosin staining of it showed a slight increase in atypical large lymphocytes, and flow cytometry of it showed CD4 and CD25 positivity in large lymphocytes. In peripheral blood samples, Southern blotting detected the monoclonal integration of the HTLV-1 provirus. Based on these findings, we diagnosed the patient with ATLL with extranodal involvement. ATLL should be included in the differential diagnosis for malignant lymphoma of the head and neck. A detailed medical interview and cooperation with the pathological department are key to a prompt diagnosis.