12.3 Breast Masses, Thyroid Nodule Evaluation & Surgical Oncology

Surgical Oncology: Breast Cancer & Thyroid Nodule Algorithms

Surgical oncology forms a critical component of General Surgery on the SMLE (~15% of total exam). Breast cancer is the most common female malignancy in Saudi Arabia (representing >30% of all female cancers in KSA). Mastery of the Triple Assessment, age-stratified diagnostic imaging algorithms, BI-RADS management categories, breast cancer staging and surgical options, as well as TSH-guided thyroid nodule evaluation and Bethesda cytological reporting, is mandatory.

Evaluation of a Palpable Breast Mass: The Triple Assessment

Any palpable breast mass or suspicious screening mammogram requires systematic evaluation via the Triple Assessment. The diagnostic concordance of all three modalities approaches 100% sensitivity:

1. Clinical Assessment: Meticulous clinical history (family history, BRCA status, nulliparity, age at menarche/menopause, hormone replacement therapy) and bilateral Clinical Breast Examination (CBE) evaluating mass mobility, skin tethering, nipple retraction/discharge, and axillary lymphadenopathy.
2. Radiological Imaging: Age-stratified imaging (Ultrasound vs. Mammography).
3. Pathological Confirmation: Core Needle Biopsy (CNB) under imaging guidance.

Age-Stratified Radiological Workup

• Women < 30 Years Old: Initial imaging of choice is Targeted Breast Ultrasound. Younger women possess dense fibroglandular breast tissue that significantly attenuates X-rays, reducing mammographic sensitivity. Ultrasound accurately differentiates fluid-filled simple cysts (benign) from solid masses (fibroadenoma vs. carcinoma).
• Women ≥ 40 Years Old: Initial imaging of choice is Diagnostic Bilateral Mammography plus targeted breast ultrasound. Mammography detects non-palpable microcalcifications (pleomorphic, linear branching)—the hallmark of early ductal carcinoma in situ (DCIS)—and architecture distortion.
• Women Aged 30 to 39 Years: Diagnostic ultrasound is performed first; mammography is added if sonographic features are suspicious or indeterminate.

Breast Imaging Reporting and Data System (BI-RADS)

BI-RADS standardizes mammographic and sonographic findings, stratifies risk of malignancy, and dictates clinical action:

Biopsy Technique Standards

• Core Needle Biopsy (CNB): The GOLD STANDARD for evaluating solid breast masses. Unlike Fine-Needle Aspiration (FNA), CNB yields a tissue core preserving histologic architecture. This allows pathologists to distinguish non-invasive (in situ) from invasive carcinoma (ductal vs. lobular) and test for biomarker expression (ER, PR, HER2/neu status).
• Fine-Needle Aspiration (FNA): Limited to therapeutic aspiration of painful simple cysts or cytological staging of palpable axillary lymph nodes. FNA CANNOT differentiate DCIS from invasive ductal carcinoma.

Surgical Management of Breast Cancer

• Breast-Conserving Surgery (BCS / Lumpectomy) + Radiation: Equivalent long-term overall survival compared to total mastectomy for early-stage disease (Stage I & II). Requires negative surgical margins.
• Axillary Staging: Sentinel Lymph Node Biopsy (SLNB) is standard of care for clinically node-negative (cN0) patients to avoid axillary lymph node dissection (ALND) morbidity (lymphedema). If SLNB is positive for macrometastases, further management (radiation vs. ALND) is evaluated.
• Neoadjuvant Systemic Therapy: Preferred for Locally Advanced Breast Cancer (LABC - Stage III) or Triple-Negative / HER2-positive tumors to downstage the tumor prior to surgery.

Diagnostic Workup of a Thyroid Nodule

Thyroid nodules are present in 5-10% of adults. Evaluation aims to identify the ~5% of nodules that represent thyroid carcinoma (Papillary, Follicular, Medullary, Anaplastic).

Stepwise Diagnostic Algorithm

1. Step 1: Serum TSH Level (Priority Laboratory Test):
   • If TSH is LOW (Suppressed): Indicates hyperthyroidism. Order a Radionuclide Thyroid Scan (Iodine-123 or Tc-99m):
     • "Hot" (Hyperfunctioning) Nodule: Takes up radioisotope preferentially. Malignancy risk is <1%. Biopsy is NOT indicated. Treat hyperthyroidism.
     • "Cold" (Non-functioning) Nodule: Fails to take up isotope. Malignancy risk ~15%. Proceed to ultrasound.
   • If TSH is NORMAL or HIGH: Malignancy risk is higher. Proceed directly to Dedicated Neck Ultrasound.
2. Step 2: High-Resolution Thyroid Ultrasound:
   • Identifies high-risk sonographic features: Solid composition, hypoechogenicity, microcalcifications, irregular/microlobulated margins, taller-than-wide shape, and extrathyroidal extension.
3. Step 3: Fine-Needle Aspiration (FNA) Cytology:
   • Performed under ultrasound guidance for nodules ≥1.0 cm with high-risk features, or ≥1.5-2.0 cm with moderate/low-risk features.

Cytological Reporting: The Bethesda System for Reporting Thyroid Cytopathology

Critical Pathological Distinction: Papillary Thyroid Carcinoma presents with characteristic nuclear features (Orphan Annie eyes nuclei, psammoma bodies, nuclear grooves) and can be diagnosed by FNA. In contrast, Follicular Carcinoma CANNOT be diagnosed by FNA because cytology cannot evaluate for capsular or vascular invasion, which defines malignancy versus benign follicular adenoma. Therefore, Bethesda IV lesions mandate surgical lobectomy for histological confirmation.