Granular cell tumor of the breast

Last revised by Henry Knipe on 30 Dec 2021

Granular cell tumors of the breast are uncommon, usually benign tumors that are possibly of neural origin.

They tend to occur at a younger age than other types of breast cancer 4. The age range of presentation, however, can be very variable although they occur more commonly in pre-menopausal women.

Clinically they can mimic carcinoma because of their fibrous consistency and their hardness, thus presenting as a palpable mass.

Granular cell tumors can occur in a variety of visceral and cutaneous sites. Most authors favor a Schwann cell origin, based on histochemical, immunohistochemical, and ultrastructural findings and on occurrence of typical lesions, within nerves. The breast accounts for ~5-8% of all granular cell tumors 2.

Cells with eosinophilic granules with abundant cytoplasm are characteristic. Positive immunohistochemical staining of the cells for S-100 protein, CD68 (KP-1) NSE, and CEA is indicative of this tumor 1. There is a negative reaction against cytokeratin.

Granular cell tumors tend to occur most commonly in the upper inner quadrant corresponding to the cutaneous sensory territory of the supraclavicular nerve.

Imaging features on both ultrasound and mammography can mimic that of more sinister breast malignancy.

On mammography, these tumors can present as ill-defined or spiculated lesions, similar to primary carcinoma.

This tumor can appear as a solid, hypoechoic, ill-defined mass, associated with a posterior shadowing, or as a well-circumscribed oval mass, associated with a posterior enhancement, depending on the extent of infiltration and degree of reactive fibrosis.

Granular cell tumors, in general, were first described by A I Abrikosoff in 1926 as a “myoblastic myoma” 7.

Usually, a wide local surgical excision is performed. While <1% of tumors are malignant, local recurrences have been reported with incomplete excision.

Considerations include other types of breast malignancy.

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