Case Presentation: A 48-year-old African American male with history of AIDS on antiretroviral therapy and Pneumocystis jirovecii pneumonia (PJP) was admitted for a two-week history of shortness of breath and 20 pound unintentional weight loss. He also noted a three-month history of worsening left leg rash, despite using topical steroids prescribed by a dermatologist for presumed nummular eczema. Admission vitals were significant for low-grade fever 100.4F, heart rate 100, and oxygen saturation 90% on room air. CD4 count was 73. Chest CT imaging showed bilateral axillary lymph node enlargement, mediastinal lymph node enlargement, right subpectoral lymphadenopathy, and splenomegaly. He was started on Atovaquone for treatment of PJP with rapid symptomatic improvement. Prior to discharge, he underwent excisional biopsy of a left axillary lymph node and punch biopsy of the left leg rash due to concerns for probable lymphoma. Excisional biopsy results showed involvement by Kaposi sarcoma with coexistent plasma cell variant of Castleman disease and positive HHV-8. Punch biopsy results were consistent with Kaposi sarcoma. The patient was diagnosed with HHV-8-associated multicentric Castleman disease and started on treatment with Rituximab, which he has tolerated well.
Discussion: Multicentric Castleman Disease (MCD) is a rare lymphoproliferative disorder that can be life-threatening. Often seen with HIV infected individuals, it has been connected with the human herpesvirus-8 (HHV-8), also known as Kaposi sarcoma herpesvirus. Although its pathogenesis remains unclear, it is thought that infection with HHV-8 leads to unregulated lymphocyte growth via vascular endothelial growth factor activity. Due to its often vague presentation and ability to mimic other diseases, including other opportunistic infections or lymphoma, delayed accurate diagnosis of MCD is a major concern. Surprisingly, the incidence of MCD has increased with more effective antiretroviral therapy for the management of HIV infection, suggesting that the disease requires a more robust immune system prior to manifestation. In the case presented here, the hyperpigmented leg lesions were mistaken for nummular eczema, and the patient was quickly presumed to have lymphoma, with the surprising diagnosis of HHV-8–associated Castleman disease only established via excisional biopsy results. He likely developed MCD after his immune system improved on antiretroviral therapy.
Conclusions: Although usually associated with a poor prognosis, including overwhelming infections, progressive disease, and hematologic malignancies, timely histopathological diagnosis and treatment with the anti-CD20 monoclonal antibody Rituximab has led to a high percentage of complete and sustained remission. As the incidence of MCD increases annually with improving HIV patient immunity, physicians must include the disease as a differential diagnosis in a HIV patient with generalized lymphadenopathy and dermatologic complaints suggestive of Kaposi sarcoma.