IS case 536: Breast embryonal rhabdomyosarcoma
Imaging Sciences URMC 2010
Publication Date: 2010-09-11
Targeted right breast ultrasound at the 12:00 position, 2 cm from the nipple demonstrated a heterogeneous hypoechoic lesion with vascular flow measuring 1.9 x 1.7 x 1.7 cm. Subsequent breast MRI demonstrated minimal background enhancement. The index lesion in the right breast was a lobular enhancing mass with a type III suspicious dynamic curve. It contained a signal void representing the biopsy clip and other areas of low signal which may indicate necrosis. No other enhancing lesions were seen in the right breast or the contralateral breast.
Primary rhabdomyosarcoma of the breast is exceedingly rare with only several case reports in the literature. The more common, albeit still extremely rare, presentation is that of metastatic rhabdomyosarcoma of the breast with primary lesions occurring in the jaw, head and neck or extremities. The origin of primary rhabdomyosarcoma of the breast may be due to mesenchymal rests, rhabdomyoblastic differentiation of tumors of mesenchymal origin or pluripotential cells from periductal and acinar mesenchymal cells. The typical presentation within the breast is that of a palpable abnormality. Initial evaluation should consist of a focused ultrasound exam and if the patient is over 30 years old a mammogram may also be performed. Rhabdomyosarcomas within the breast have nonspecific, malignant appearing characteristics on all imaging modalities. Biopsy is required for diagnosis. Even with tissue evaluation, the diagnosis is challenging. Differentiating between the multiple varieties of nonepithelial spindle cell or sarcomatous lesions is difficult and can lead to false diagnoses. Due to the aggressive nature of this disease, a thorough search for metastases is required.
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