Rhabdomyosarcoma in a child with massive pleural effusion: cytological diagnosis from pleural fluid.

We report on a case of embryonal rhabdomyosarcoma in an 11-yr-old boy investigated for mild chest pain after trauma. Chest radiography showed a massive right pleural effusion. Cytological analysis of the pleural fluid demonstrated the presence of malignant small undifferentiated cells. The rhabdomyoblastic nature of the cells was confirmed by positive immunostains of HHf35 actin, desmin, and skeletal muscle myosin; histological examination of a core biopsy confirmed the diagnosis of rhabdomyosarcoma. Computed tomography and gallium scan revealed the presence of an extensive anterior and lower chest wall mass involving the mediastinum, as well as retroperitoneal lymphadenopathy. Massive pleural effusion is a frequent presentation in malignant disease, but is rare in rhabdomyosarcoma. The immunochemical stain studies performed on cytological smears in this case proved to be very useful for making the definitive and accurate diagnosis. Diagn. Cytopathol. 1999;21:125-128. Copyright 1999 Wiley-Liss, Inc.