What is the management approach for a granular cell tumor (GCT) of the breast?

Management of Granular Cell Tumor of the Breast

Wide local excision with clear margins is the definitive treatment for granular cell tumor (GCT) of the breast, as these benign but locally infiltrative tumors are cured by complete surgical removal. 1, 2

Diagnostic Approach

Core Needle Biopsy is Essential

• Core needle biopsy must be performed before surgical excision to establish the correct diagnosis and avoid unnecessary radical mastectomy, as GCTs frequently mimic breast cancer on clinical examination and imaging 3, 1
• Fine-needle aspiration cytology can be useful, showing histiocytic cells with abundant granular cytoplasm, though core biopsy provides superior tissue architecture 3
• Immunohistochemistry is diagnostic: positive S-100 protein, CD68, and NSE staining with absent cytokeratin, estrogen receptor, and progesterone receptor expression 4, 2

Imaging Characteristics That Mimic Malignancy

• Mammography typically shows a dense, irregular mass with spiculation and skin thickening that resembles invasive ductal carcinoma 3
• Ultrasound reveals a hypoechoic mass with irregular borders and intense posterior acoustic shadowing 3, 2
• These misleading features make histological confirmation absolutely critical before proceeding with definitive surgery 3, 4

Surgical Management

Wide Local Excision Technique

• The incision should be placed directly over or close to the tumor and of adequate size to allow removal of the lesion in one piece 5, 6
• Excise the tumor with a rim of grossly normal tissue to ensure adequate margins, as GCTs can be locally aggressive and infiltrative 5, 1, 2
• Meticulous hemostasis is critically important to prevent hematoma formation, which complicates healing and future imaging interpretation 5, 6
• Avoid drains in the breast, as they increase infection risk without improving outcomes 5, 6

Specimen Handling

• The specimen must be oriented properly with sutures, clips, or multicolored ink before submission to pathology to allow accurate margin assessment 5
• Remove the entire tumor in one piece—do not section the specimen before pathologic examination, as this compromises margin evaluation 5, 6
• Send all excised tissue for histopathologic examination to confirm the diagnosis and assess margins 5

Margin Assessment

• Careful evaluation of surgical margins is essential, as inadequate margins may require re-excision given the locally infiltrative nature of GCTs 1, 2
• If margins are inadequate on final pathology, re-excision should be performed 5
• Place clips outlining the excision cavity to demarcate the tumor bed for future imaging surveillance 5

Special Considerations

Avoid Radical Surgery

• Radical mastectomy is unnecessary and should be avoided for GCT, as these are benign tumors despite their aggressive imaging appearance 3
• Historical cases of unnecessary mastectomy underscore the importance of preoperative tissue diagnosis 3

Extensive Disease

• In rare cases with extensive chest wall invasion, a multidisciplinary surgical approach may be required 7
• Even with chest wall involvement, the tumor remains benign and complete excision is curative 7, 2

Cosmetic Closure

• Close skin with subcuticular technique to optimize cosmetic results 5, 6
• Preserve subcutaneous tissue with separate closure 5, 6
• Avoid reapproximating breast tissue in a way that appears adequate only when the patient is supine, as this causes distortion when upright 5

Follow-Up and Prognosis

• Long-term follow-up is recommended, though recurrence is rare (approximately 8% in one series) with adequate excision 1
• The vast majority of GCTs are benign and cured by wide local excision with clear margins 2
• No adjuvant therapy is required for benign GCT 1, 2

Critical Pitfalls to Avoid

• Never proceed directly to mastectomy based on imaging alone—always obtain tissue diagnosis first, as GCTs are benign despite mimicking malignancy 3, 4
• Do not perform fine-needle aspiration alone without core biopsy, as architectural features are important for diagnosis 3
• Avoid inadequate margins at initial excision, as re-excision increases morbidity and compromises cosmesis 1
• Do not section the specimen before pathologic examination, as this prevents accurate margin assessment 5