What is the standard procedure for a microdochectomy (surgical removal of a breast duct)

Microdochectomy: Standard Surgical Procedure

Overview

Microdochectomy is a targeted surgical excision of a single mammary duct system, typically performed through a periareolar incision to remove the affected duct from the nipple to its terminal branches, primarily indicated for pathologic single-duct nipple discharge. 1, 2

Indications

• Single-duct pathologic nipple discharge (bloody, serosanguinous, or spontaneous discharge from one duct opening) is the primary indication 3, 2, 4
• Persistent symptomatic discharge even when imaging and cytology are normal or benign 2, 4
• Presence of epithelial cells on nipple smear cytology 2
• Important caveat: If pre-operative mammography shows highly suspicious findings, proceed directly to more extensive excision rather than microdochectomy, as 8-10% of cases may harbor ductal carcinoma in situ 3, 2

Pre-operative Preparation

• Complete mammographic evaluation is mandatory before surgery 3, 4
• Breast ultrasound should be performed to assess for underlying masses 4
• Duct identification: The specific discharging duct must be clearly identified at the nipple before surgery 1
• Consider duct endoscopy when available to visualize intraductal lesions and potentially perform endoscopic biopsy, which can be diagnostic without sacrificing normal breast tissue 5

Surgical Technique

Incision and Approach

• Periareolar incision is the standard approach, placed at the areolar margin for optimal cosmesis 1
• The incision should be positioned to allow direct access to the affected duct without tunneling 1
• Transareolar dye injection technique can be used: inject methylene blue or similar dye into the discharging duct opening to facilitate identification and complete excision of the ductal system 1

Dissection Principles

• Identify the affected duct at the nipple and trace it proximally through the breast tissue 1
• Use anatomical tissue planes and microdissection techniques to minimize trauma to surrounding normal breast tissue 1
• Maintain a bloodless surgical field through meticulous hemostasis 1
• Excise the entire ductal system from nipple to terminal branches, removing it as a single intact specimen 1
• The specimen should be removed in one piece rather than fragments to allow proper pathologic assessment 6

Hemostasis and Closure

• Meticulous hemostasis is critical as hematoma formation produces long-lasting changes that complicate physical examination and may lead to unnecessary future biopsies 6
• Avoid placing drains in the breast; allow the cavity to fill with serum for better cosmetic results 6
• Close skin incisions with subcuticular technique for optimal cosmesis 6

Specimen Handling

• Orient the specimen for pathologic examination 1
• Send the entire duct system for histopathologic analysis 1, 2
• Request evaluation for papilloma, duct ectasia, atypical hyperplasia, and carcinoma 2, 4

Expected Pathology

• Intraductal papilloma is the most common finding (48.7% of cases) 2
• Duct ectasia occurs in 15.8% 2
• Combined papilloma and ectasia in 13.2% 2
• Malignancy is found in approximately 5-10% of cases, even with normal pre-operative imaging 3, 2, 4
• Other benign causes account for 11.8% 2

Post-operative Management

• Symptomatic relief occurs in 98% of patients with benign disease 2
• Recurrence of discharge is rare (less than 2%) 2
• If atypical ductal hyperplasia is found, close surveillance is required as these patients remain at risk for subsequent cancer development 4
• If carcinoma is identified, proceed with appropriate oncologic management including re-excision for margin assessment 3, 2

Critical Pitfalls to Avoid

• Do not rely solely on negative imaging to exclude malignancy: imaging sensitivity for detecting neoplasia in pathologic nipple discharge is poor (mammography 7%, ultrasound 26%) 4
• Do not perform expectant management without tissue diagnosis unless the discharge is clearly related to pregnancy or infection 4
• Avoid incomplete duct excision, which may lead to recurrent symptoms 1
• Do not tunnel through breast tissue; place incisions close to the pathology 6

Alternative Approach

• For patients where duct endoscopy is available, endoscopic biopsy can provide diagnosis with minimal tissue sacrifice, particularly useful for small benign papillomas 5
• However, complete microdochectomy remains both diagnostic and therapeutic in a single procedure 1, 2