PA30.1-5 | Breast — Graded Quiz

A 36-year-old woman undergoes core needle biopsy of a 2.8 cm right breast mass. Histology shows small, uniform, loosely cohesive cells filling and distending terminal duct-lobular units (TDLUs) without invading the surrounding stroma. The cells have round nuclei, inconspicuous nucleoli, and intracytoplasmic vacuoles (targetoid mucin). E-cadherin immunostaining is NEGATIVE. She is otherwise healthy. Which statement about the MANAGEMENT IMPLICATION of this finding is MOST accurate?

A 43-year-old woman presents with a 3.2 cm left breast mass with skin dimpling. Core biopsy shows a carcinoma with the following features: tubule formation score 3, nuclear pleomorphism score 3, mitotic count score 3 (Nottingham score 9/9, Grade 3). IHC: ER 0%, PR 0%, HER2 IHC 2+ (equivocal). FISH shows HER2:CEP17 ratio = 1.8 (negative). Her sister was diagnosed with ovarian carcinoma at age 42. What is the MOST appropriate next investigation and its expected therapeutic implication?

A 47-year-old woman presents with a rapidly enlarging left breast mass over 4 months. On examination, the breast is warm, erythematous, and the skin is oedematous with an orange-peel texture (peau d'orange). She is afebrile. FNA of the skin shows carcinoma cells within dilated dermal lymphatic channels. Core biopsy of the underlying mass shows infiltrating carcinoma with comedo necrosis. Which pathological mechanism DIRECTLY explains the peau d'orange appearance?

A 38-year-old woman has breast conservation surgery for a 1.8 cm Grade 2 invasive carcinoma NST. ER = 95% strong, PR = 70%, HER2 = 0, Ki-67 = 6%. Nottingham grade 1 (score 4/9). The radiation oncologist asks the pathologist for a genomic assay recommendation. Oncotype DX Recurrence Score returns 11 (low). One axillary sentinel lymph node is positive with a 0.8 mm micrometastasis. What is the MOST accurate clinical interpretation and treatment implication?

A 52-year-old man presents with bilateral breast enlargement. His medications include finasteride (for BPH), digoxin (for atrial fibrillation), and atorvastatin. He has normal liver function and normal testosterone. Which medication is MOST likely responsible for his gynecomastia, and what is its mechanism?

A 44-year-old woman presents with eczematous, crusting, and weeping changes confined to the left nipple and areola for 5 months. A punch biopsy of the nipple skin shows large cells with abundant pale cytoplasm, vesicular nuclei, and prominent nucleoli scattered individually within the epidermis. The cells do not form glands. HER2 IHC: 3+ (strongly positive) in the intraepidermal cells. ER: positive. A 1.4 cm retroareolar mass is palpable. What additional study is MOST helpful in determining the full extent of disease, and why?

A pathology trainee reviews a core biopsy from a 55-year-old woman's 3.5 cm breast mass. The histological report reads: 'Well-circumscribed mass; sheets of cells with high nuclear-to-cytoplasmic ratio and syncytial growth pattern; prominent lymphoplasmacytic infiltrate throughout the tumour; pushing borders at the deep margin; geographic necrosis present.' IHC: ER 0%, PR 0%, HER2 0. The trainee suggests this must be DCIS with comedo necrosis. What is the CORRECT diagnosis, and what is the MOST important distinguishing feature?

A 51-year-old woman has a mammogram showing a 1.2 cm stellate density in the upper outer quadrant of the right breast. Core biopsy shows a small glandular lesion with a central fibrous core, irregular distorted glands, and pseudoangiomatous spaces — the pathologist reports 'radial scar.' At surgical excision, the final diagnosis is 'radial scar with atypical ductal hyperplasia (ADH) at the margin.' What is the MOST important clinical implication of finding ADH in this radial scar?

A 48-year-old woman is found to have a 5.5 cm left breast mass. Biopsy confirms invasive carcinoma NST, Grade 3, ER+, PR+, HER2 3+, Ki-67 42%. The surgical oncologist proposes neoadjuvant chemotherapy (NACT) with trastuzumab + pertuzumab. Post-NACT, surgical specimen shows NO residual invasive carcinoma in the breast or lymph nodes (ypT0/ypN0 — pathological complete response, pCR). What does pathological complete response MOST reliably predict in this molecular subtype?

A 39-year-old woman presents with a rapidly growing right breast lump. Excision biopsy reveals a tumour with leaf-like stromal projections lined by benign epithelium, markedly hypercellular stroma, 15 mitoses per 10 HPF, stromal nuclear pleomorphism, and areas of haemorrhagic necrosis. The margins are involved. A colleague suggests that because the epithelial component is benign (no atypia), this is a benign phyllodes tumour and re-excision to clear margins is sufficient treatment. What is the MOST accurate counter-argument?

A 65-year-old woman presents with a firm, irregular 2 cm breast mass. Mammography shows an irregular, spiculated density with microcalcifications. Core biopsy histology: infiltrating cords and single files of small monomorphic cells in a desmoplastic stroma ('Indian file' and 'targetoid' concentric fibrosis around pre-existing ducts). E-cadherin: completely absent. IHC: ER 80%, PR 40%, HER2 0, Ki-67 12%. No Nottingham grade because tubule formation is inapplicable. What management decision is MOST directly affected by the targetoid/perineural pattern and mammographic 'occult' nature of this carcinoma?

A 33-year-old woman presents during the third trimester of her first pregnancy with a 2 cm firm mass in the right breast. Ultrasound shows a hypoechoic mass with irregular margins. Core biopsy shows Grade 3 invasive carcinoma NST, ER 0%, PR 0%, HER2 3+. Her obstetrician and oncologist discuss management options. Which statement about treatment in this scenario is MOST accurate?