Breast Discharge: An MCCQE1 Comprehensive Guide

Introduction

Nipple discharge is a common breast complaint in primary care and gynecology, accounting for approximately 5-10% of breast symptoms reported by women. For the MCCQE1, candidates must demonstrate the Medical Expert role by distinguishing between physiological and pathological discharge, identifying “red flags” for malignancy, and ordering appropriate investigations within the Canadian healthcare context.

While the majority of nipple discharge is benign, the primary clinical objective is to rule out breast cancer (e.g., Ductal Carcinoma In Situ - DCIS).

Classification and Etiology

Understanding the nature of the discharge is the first step in triage. The MCCQE1 often tests the ability to categorize symptoms to narrow the differential diagnosis.

Clinical Evaluation

History Taking

A focused history is crucial for the MCCQE1 CDM (Clinical Decision Making) component.

• Nature: Spontaneous vs. Expressed? Unilateral vs. Bilateral?
• Colour: Bloody, serous, milky, or green/black?
• Duration: Acute vs. Chronic?
• Associated Symptoms: Palpable mass? Skin changes (peau d’orange, erythema)? Inverted nipple?
• Medications: Review for dopamine antagonists.
• Reproductive History: Pregnancy status, Last Menstrual Period (LMP).

Physical Examination

Perform a systematic breast examination.

Differential Diagnosis Summary

Use this table to quickly differentiate causes during your exam study.

Investigations and Management

The diagnostic approach depends on whether the discharge is suspicious (pathologic) or physiologic.

Diagnostic Algorithm

1. Pathological Discharge (Unilateral, Bloody, Spontaneous)

• Imaging (Canadian Standard):
  • Age < 30: Ultrasound is the primary modality.
  • Age ≥ 30: Diagnostic Mammography + Ultrasound (retroareolar focus).
  • MRI: Considered if conventional imaging is negative but discharge persists and is suspicious (refer to specialist).
• Procedures:
  • Ductography (Galactography): Rarely used now in Canada; replaced by high-resolution US and MRI.
  • Cytology: Low sensitivity. Generally not recommended by Canadian guidelines as a negative result does not rule out cancer.
  • Biopsy: If a mass is seen on imaging (Core Needle Biopsy). If no mass but suspicious discharge persists, surgical excision of the duct (microdochectomy) is both diagnostic and therapeutic.

2. Physiological/Galactorrhea

• Pregnancy Test (Beta-hCG): Rule out pregnancy.
• Serum Prolactin: Evaluate for hyperprolactinemia.
• TSH & Creatinine: Rule out hypothyroidism and renal failure.
• Medication Review: Discontinue offending agents if possible.

Management Strategies

• Intraductal Papilloma: Surgical excision (microdochectomy) to confirm diagnosis and rule out adjacent malignancy.
• Duct Ectasia: Reassurance. Smoking cessation. Surgery only if symptoms are severe/recurrent.
• Galactorrhea: Treat underlying cause (e.g., Dopamine agonists like Cabergoline for prolactinoma; Thyroid replacement for hypothyroidism).
• Malignancy: Refer to Surgical Oncology.

# Medical Abbreviations for MCCQE1
- DCIS: Ductal Carcinoma In Situ
- BI-RADS: Breast Imaging-Reporting and Data System
- CNB: Core Needle Biopsy
- FNA: Fine Needle Aspiration

Key Points to Remember for MCCQE1

1. Most Common Cause: Intraductal papilloma is the most common cause of bloody nipple discharge.
2. Cytology: Nipple discharge cytology has a high false-negative rate and is not a standard screening tool in Canada.
3. Male Patients: Any nipple discharge in a man requires a workup for breast cancer (mammogram + US).
4. Imaging Age Cut-off: Remember the age of 30 (or sometimes 35 depending on specific provincial guidelines, but 30 is a safe exam anchor) for adding mammography to ultrasound.
5. Choosing Wisely Canada: Do not order an MRI for breast discharge unless referred by a specialist or conventional imaging is inconclusive for a highly suspicious lesion.

Sample Question

Clinical Scenario

A 45-year-old female presents to her family physician complaining of staining on her bra cup. She reports a 3-week history of spontaneous, bloody discharge from her left nipple. She has no history of trauma. Her past medical history is unremarkable. On physical examination, there is no palpable breast mass, no axillary lymphadenopathy, and no skin changes. Gentle pressure on the left breast elicits a drop of serosanguineous fluid from a single duct at the 3 o’clock position. A diagnostic mammogram and retroareolar ultrasound are performed and are reported as BI-RADS 2 (benign findings, no mass seen).

Question

Which of the following is the most likely diagnosis?

• A. Ductal Carcinoma In Situ (DCIS)
• B. Mammary Duct Ectasia
• C. Intraductal Papilloma
• D. Fibroadenoma
• E. Prolactinoma

Explanation

The correct answer is:

• C. Intraductal Papilloma

Explanation:

• C is correct: Intraductal papilloma is the most common cause of pathologic (spontaneous, unilateral, bloody/serous) nipple discharge in women of this age group. The absence of a mass on imaging does not rule it out, as papillomas are often too small to be seen on standard mammography.
• A is incorrect: While DCIS can present with bloody discharge, it is less common than papilloma. However, because it is a differential, surgical excision is often performed to rule it out.
• B is incorrect: Duct ectasia typically presents with thick, green/black discharge and is often bilateral or associated with nipple retraction in perimenopausal women.
• D is incorrect: Fibroadenomas present as solid, mobile masses, usually in younger women (<30), and are rarely associated with bloody discharge.
• E is incorrect: Prolactinoma causes galactorrhea (bilateral, milky discharge), not unilateral bloody discharge.

Canadian Guidelines

• Screening: Diagnostic imaging (not screening) is indicated for symptomatic patients.
• Referral: Canadian pathways typically mandate referral to a surgeon (General or Breast Oncoplastic) for any spontaneous, unilateral, bloody discharge, even if imaging is normal, to consider duct excision.
• Wait Times: Provincial guidelines aim for assessment of “highly suspicious” breast symptoms within 2-3 weeks.

References

1. SOGC Clinical Practice Guidelines. Management of Breast Conditions. Journal of Obstetrics and Gynaecology Canada.
2. CMAJ (Canadian Medical Association Journal). Diagnosis and management of nipple discharge.
3. Choosing Wisely Canada. Breast Cancer Screening and Diagnosis.
4. UpToDate. Nipple Discharge: Clinical Manifestations and Diagnosis. (Accessed via Canadian Medical Association portal).
5. Medical Council of Canada. Objectives for the Qualifying Examination Part I.