RESUMEN
BACKGROUND: Primary effusion lymphoma (PEL) is a highly malignant non-Hodgkin lymphoma associated with Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8 infection (KSHV/HHV-8). It is chiefly seen in HIV patients and is rare in transplant recipients, possibly going unrecognized. OBSERVATION: We describe two male kidney transplant recipients, aged 47 and 51 years, followed for Kaposi's sarcoma in skin, lymph nodes, gastrointestinal (GI) tract and lung whose disease was poorly controlled by sirolimus and chemotherapy. Recurrent pleural effusion contrasted with reduction of cutaneous Kaposi lesions. KHSV viral loads were negative or very low in plasma, were negative or very low, whereas those in pleural effusion were high. Lymphoma cells were discovered only seven to nine months after the initial effusion despite repeated needle biopsies. In one patient, tumour cells were co-infected with Epstein-Barr virus. CONCLUSION: The contrast between a very low KHSV viral load in plasma and a very high viral load pleural effusion should alert physicians and prompt suspicion of PEL in Kaposi's sarcoma patients with recurrent serous effusion. The potential inhibitory role of sirolimus on PEL progression is discussed.