Granular cell tumour of the breast

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

Epidemiology

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.

Clinical presentation

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

Pathology

Granular cell tumours can occur in a variety of visceral and cutaneous sites. Most authors favour 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 tumours ².

Microscopic appearance

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 tumour ¹. There is a negative reaction against cytokeratin.

Location

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

Radiographic features

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

Mammography

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

Ultrasound

This tumour 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.

History and etymology

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

Treatment and prognosis

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

Differential diagnosis

Considerations include other types of breast malignancy.