Image Description
Cardiac rhabdomyomas are composed of large vacuolated cells with abundant glycogen - so called "spider cells." This appearance is caused by centrally placed nucleus from which myofibrils radiate to the cell membrane. PAS stain is strongly positive due to glycogen. With electron microscopy, these cells are found to have abundant glycogen, few irregular myofibrils and a poorly-developed sarcoplasmic reticulum.
This photomicrograph shows atrial rhabdomyoma in a 1 y/o male. Image courtesy of: Dr. Jose Bellasai, Professor of Pathology, Univ. National & Univ. Catholic of Asuncion, Paraguay.
About the Disease
Primary cardiac tumors are extremely uncommon. Secondary tumors (metastases to heart) are 20-50 times more common than primary cardiac tumors and yet still relatively rare. Of primary cardiac tumors, almost 75% are benign and the remaining 25% are malignant.Benign Primary Cardiac Tumors: Myxoma (50-70% of cases), rhabdomyoma, lipoma and lipomatous hypertrophy of interatrial septum, papillary fibroelastoma, and fibroma. Angiomas and teratomas are found mainly in children. Malignant Primary Cardiac Tumors: Mostly sarcomas, including angiosarcoma (30%), rhabdomyosarcoma (20%), leiomyosarcoma, liposarcoma, osteosarcoma, fibrosarcoma, and undifferentiated pleomorphic sarcoma. Other tumors include mesothelioma and lymphoma.Secondary cardiac tumors are far more frequent than primary cardiac tumors. The most common primary sites include melanoma, lung, breast, kidney, and lymphomas. Pericardium is usually affected, resulting in pericardial effusion.Cardiac tumors may be asymptomatic and found incidentally or present with obstructive, embolic, arrhythmic or systemic symptoms, depending upon the size and location of the mass. References: 1. Miller, D. V. & Revelo M. P. (2023). Diagnostic Pathology - Cardiovascular. 3rd Edition, Elsevier.2. Sheppard, M. N. (2022). Practical Cardiovascular Pathology 3rd Edition, CRC Press.3. Maximilian B. & Butany J. (2022). Cardiovascular Pathology 5th Edition, Academic Press.