Eosinophilic pleural effusion as the first presentation of angioimmunoblastic T cell lymphoma

Eosinophilic pleural effusion (EPE), defined as pleural effusion that contains at least 10% eosinophils among the leukocytes, can be a manifestation of a great variety of diseases. However, eosinophilia is a relatively rare finding in malignant pleural effusions, and it has been used as an indicator of good prognosis. In clinical experience, very few cases of malignant lymphomas accompanied by EPE have been reported. In this report, we present an 82-year-old otherwise healthy man with the initial presentation of left EPE. Pleural biopsy could not yield a definite diagnosis initially. Hookworm ova were also found in the stool and parasite associated with EPE was suspected. However, after anti-parasitic agent treatment with mebendazole, the pleural effusion did not improve. Six months later, bilateral neck, axillary and inguinal lymphadenopathy developed, and lymph node biopsy confirmed the diagnosis of angioimmunoblastic T cell lymphoma, with positive CD10 expression. Therefore, we retrospectively carried out CD10 staining of the sample obtained from pleural biopsy and the positive result confirmed that the etiology of EPE was due to malignant T cell lymphoma. The patient refused chemotherapy and he died 1 month later.