We present a 56-year-old woman who came to the emergency department with an exertional dyspnea of recent onset. A transthoracic echocardiographic examination revealed two round masses in her left atrium with mild mitral stenosis and mild-to-moderate mitral valve regurgitation.
Her laboratory data were unremarkable except for a mild anemia. Surgical excision of the masses was performed, and two creamy-white fleshy tumors were removed. On cross section, they were solid and creamy-brown with gritty areas.
Histopathological examination showed extensive sheets of round to oval cells, and hemangiopericytoma-like patterns.
Also, multiple lobules of well-differentiated hyaline cartilage were present. An immunohistochemistry (IHC) panel revealed that the chondroid areas were reactive for S100 protein. The round cells expressed CD99 with focal positivity for NSE (neuron-specific enolase), but were negative for the following cytokeratin, CD34, factor VIII, actin, and desmin. Therefore, the cells were mesenchymal in origin with chondroid differentiation, and the final diagnosis was a mesenchymal chondrosarcoma.
A full-scale investigation into the source of the tumor was unrevealing. Shortly after her discharge from the hospital, she developed an embolic cerebrovascular accident.