Anaplastic large cell lymphoma presenting as retroperitoneal lymphadenopathy in a person living with human immunodeficiency virus.

Although B-cell lymphomas are the most common malignancies in people living with HIV, T-cell lymphomas, such as anaplastic large cell lymphoma (ALCL), have also been described in people living with HIV, with frequent extranodal involvement and a poor prognosis when associated with a lack of anaplastic lymphoma kinase (ALK) expression. We present a case of a man in his late 30s with a 2 year history of HIV and adequate antiretroviral therapy (ART) adherence who presented with worsening oppressive low back pain radiating to the abdomen and constitutional symptoms. Imaging revealed retroperitoneal lymphadenopathy and biopsy showed CD30+and ALK-negative large atypical anaplastic lymphocytes consistent with ALK-negative ALCL. As expected in ALK-negative ALCL, the patient deteriorated quickly and died hours after starting chemotherapy. This case highlights the importance of including HIV-associated malignancies, including T-cell lymphomas, in our differential diagnosis to allow prompt initiation of targeted therapy in case of a rapidly progressing malignancy.