Cardiac Rhabdomyoma

General: The most common cardiac tumor in the pediatric population, and often presents with heart failure or dysrhythmias. Noninvasive and nonmetastasizing; considered overgrowths of myocardium or hamartomas, rather than "true" neoplasms, and often regress after the first few years of life. Of children with tuberous sclerosis, ~50% have cardiac rhabdomyomas, often multiple, and sometimes termed rhabdomyomatosis. Assoicated with mutations of the TSC1 (encoding hamartin) and TSC2 (encoding tuberin) genes.

Gross: Multiple well circumscribed tumors ranging in size from millimeters to > 6 cm, with a mean reported size of 3.4 cm.

Microscopic: Multiple well-circumscribed, variably sized tumor nodules composed of large vaculoated cells with clear cytoplasm. No mitoses. Characterized by spider cell, a large vacuolated cell with delicate radiating strands from the nucleus to the cell membrane.

Differential Diagnosis:

• Glycogen storage disease, Pompe disease, alpha-glucosidase deficiency
• Granular cell tumor
• Histiocytoid cardiomyopathy

Stains:

• Positive: Actin, desmin, myoglobin, vimentin; focally positive for HMB45, PAS positive glycogen containing vacuoles
• Negative: Cholinesterase, Sudan black, S100
• Suggested, focused panel:

(Lefkowitch: AP Board Review)

Images:


Cases:

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