Rationale: Eosinophilic pleural effusion in elderly patients is most commonly due to malignancies and infections.
Patient concerns: In rare cases, pleural eosinophilia is associated with connective tissue disease.
Diagnoses: Presence of Hargraves cells, also called lupus erythematosus (LE) cells (polynuclear cells that have engulfed denatured nuclear material), was a key point of American College of Rheumatology (ACR) classification criteria for systemic lupus erythematosus (SLE) until 1997. Now replaced by serology for autoantibodies, LE cells characterization remains useful in guiding the diagnostic strategy towards autoimmune diseases.
Interventions: An 82-year-old woman complained about anorexia, weight loss, fatigue, and mild night fever. Clinical examination disclosed a left pleural effusion without parenchymal lesion on high contrast thoraco-abdomino-pelvic computed tomography scan. A thoracocentesis revealed an exudate with eosinophilia. Direct cytological examination showed LE cells. SLE was rapidly considered. Antinuclear antibodies were subsequently found in the serum and in the pleural effusion. Anti-nucleosome antibodies were also present without antiphospholipid antibodies. Her condition rapidly improved after initiation of prednisone and hydroxychloroquine.
Outcomes: Six months later, the patient had no particular complain, clinical examination was strictly normal biological parameter were in normal range.
Lessons: The assessment of an eosinophilic pleural effusion allowed to find LE cells, which rapidly suggested the diagnosis of SLE, and early initiation of appropriate treatment. LE cells are no longer a criterion for the diagnosis of SLE, but their presence in serosa is most helpful in guiding the diagnostic strategy, and specifically in atypical forms often seen in older patients.