# Case Report: A very rare case of a pleural effusion revealing multiple myeloma

## TL;DR

This case report describes a rare instance where a pleural effusion was the first sign of multiple myeloma in a 71-year-old patient.

## Contribution

The novelty lies in presenting a rare clinical case of myelomatous pleural effusion as the initial manifestation of multiple myeloma.

## Key findings

- The patient had a massive left-sided pleural effusion with multinodular pleural thickening.
- Diagnosis was confirmed via biopsy showing abnormal plasma cells with CD138 and MUM1 markers.
- The patient passed away one month after diagnosis, highlighting the poor prognosis of this condition.

## Abstract

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.