Case Report: A very rare case of a Pleural Effusion revealing Multiple Myeloma [version 3; peer review: 1 approved, 2 approved with reservations]

Multiple myeloma is a common malignant bone-based disease. Pleural effusions reported in these patients remain rare. It is commonly due to congestive heart disease, pulmonary embolism, nephrotic syndrome or a second neoplasia. The true myelomatous pleural effusion resulting from a direct tumoral invasion of the pleural are extremely rare. We report here the case of a massive pleural effusion revealing multiple myeloma in a 71-year-old patient. The chest ultrasound showed a massive pleural effusion in the left side with a multinodular thickening of the pleura. The medical thoracoscopy showed a grape-cluster appearance. The diagnosis was made by pleural guided biopsy revealing abnormal plasma cells with an intense positive CD 138 (plasma cell marker) and MUM1 (multiple myeloma oncogene1) staining with a light kappa chain in the protein electrophoresis associated with a myeloma. Unfortunately, our patient died one month after the initial diagnosis. We present also a review of the recent literature in order to highlight the clinical presentations of the myelomatous pleural effusion, the diagnostic tools, the therapeutic strategies as well as the outcomes