Extraordinary Case ReportPanniculitis-Like Presentation of Extracavitary Primary Effusion LymphomaSaggini, Andrea MD*; Di Prete, Monia MD*; Facchetti, Simone MD*; Rapisarda, Vito Mario MD†; Anemona, Lucia MD*Author Information *Anatomic Pathology, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy; and †Hematology, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy. Correspondence: Andrea Saggini, MD, Anatomic Pathology, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Viale Oxford 81, Rome 00173, Italy (e-mail: email@example.com). The authors declare no conflicts of interest. The American Journal of Dermatopathology: June 2020 - Volume 42 - Issue 6 - p 446-451 doi: 10.1097/DAD.0000000000001539 Buy Metrics Abstract Primary effusion lymphoma (PEL) is defined as a HHV-8-associated large B-cell lymphoma, which favors HIV-infected young adults, typically presenting as a serous (pleural, pericardial, or peritoneal) effusion with no identifiable tumor mass. Uncommon instances of lymphoid proliferations with the same morphology, immunophenotype, and molecular features as PEL, but occurring as a solid tumor mass without serous cavities involvement, have been termed extracavitary (or solid) variant of PEL. We hereby report the exceptional case of a HIV-associated extracavitary PEL primarily localized to the skin and exhibiting a panniculitis-like presentation. Primary cutaneous presentation of extracavitary PEL is exceedingly uncommon, with only 6 cases previously described in the literature. In light of its atypical immunophenotype, the differential diagnosis in case of skin involvement by extracavitary PEL is challenging: demonstration of HHV-8 infection in neoplastic cells is of pivotal importance. Our case is further atypical in that the lymphoid proliferation underwent complete and protracted regression solely by establishment of highly active antiretroviral therapy. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.