Breast Flashcards
Breast containing cells with bland round nuclei, pale cytoplasm, may be plasmacytoid in shape with an intracytoplasmic lumen or eccentric mucin vacuole. Infiltrate stroma singly, as single file lines, and often form concentric rings around ducts, all without an appreciable desmoplastic response
Invasive lobular carcinoma
Differential diagnosis
Metastatic signet ring cell carcinoma (gastrointestinal)
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, areas of differing morphology)
IPX to support Dx: ER, PR, HER2, Ki67, E-cadherin (expect ER/PR positive, HER2 negative, e-Cadherin negative)
Next steps: Synoptic report, discuss at MDT
Highly infiltrative breast lesion with perineural invasion. Predominant myoepithelial cells impart a basaloid appearance. Growth pattern can be tubular, cribriform, or solid. Tumour cells are surrounded by hyalnized reduplicated basement membrane material.
Adenoid cystic carcinoma
Differential diagnosis:
Collagenous spherulosis
Cribriform carcinoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, extent of PNI/LVI, etc)
IPX to support Dx: cKIT, MYB, ER and PR, HER2, Ki67 (expect cKIT/MYB positive, ER/PR/HER2 negative)
Next steps: Synoptic report, discuss at MDT
Breast with proliferation of acini of lobules which form small uniform tubules. The epithelial cells are small/atrophic. In sclerosing variant the ductules are compressed / distorted by fibrosis which can make them look infiltrative, but they retain a lobular architecture at low power. Myoepithelial cells are present. Microcalcifications are common and can be present in either fibrotic stroma or glandular lumina.
Sclerosing adenosis
Differential diagnosis:
Radial scar / complex sclerosing lesion
Microglandular adenosis
Invasive breast carcinoma
Plan:
Correlate with clinical history / radiology
Examine further blocks
IPX to support Dx: CK5/6, p63 (highlight intact myoepithelial cells)
No specific action required for this benign diagnosis
Breast tumour with a well circumscribed pushing edge, syncytial growth (poorly defined cell borders), and high histological grade, also has prominent tumour infiltrating lymphocytes (TILs).
Medullary carcinoma (invasive carcinoma of no special type, with medullary pattern)
Differential diagnosis:
Metastatic poorly differentiated carcinoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, areas of differing morphology)
IPX to support Dx: GATA3, ER, PR, HER2, Ki67 (expect GATA3 positive, ER/PR/HER2 negative, high Ki67)
Next steps: Formal grade, synoptic report, discuss at MDT
Advice to clinician: Although a high grade triple negative tumour, has better prognosis than stage/grade matched triple negative tumours without medullary features, and this is thought to be due to high tumour infiltrating lymphocytes (TILs)
Breast lesion with neoplastic cells (with low or intermediate nuclear grade) and abundant extracellular mucin. Frequently show neuroendocrine differentiation.
Mucinous breast carcinoma
Differential diagnosis:
Metstatic mucinous carcinoma of another primary site (e.g. colorectal, lung, gynaecologic)
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, areas of differing morphology, relation to margins) - must be >90% of total tumour to qualify as pure mucinous breast carcinoma
IPX to support Dx: GATA3, ER and PR, HER2, Ki67 (expect GATA3, ER and PR positive)
Next steps: Synoptic report, discuss at MDT
Breast lesion in a male with usual ductal hyperplasia and proliferation of stroma with periductal oedema and pseudoangiomatous stromal hyperplasia. Lobules are absent.
Gynaecomastia
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for evidence of ADH/DCIS)
IPX to support Dx: Not required
No further specific action required for this benign diagnosis
Biphasic breast tumour with ‘exaggerated intracanalicular growth,’ meaning that multiple projections bulge into the ductal lumina, creating a ‘leaf like’ appearance. They also show increased stromal cellularity, which is accentuated around ducts ‘subepithelial stromal condensation.’
Phyllodes tumour
Differential diagnosis:
Fibroadenoma
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, features of borderline/malignant)
IPX to support Dx: Not required
Next steps: Synoptic report
Breast lesion with a spectrum of benign fibrocystic changes, forming a stellate architecture radiating outward from a central fibroelastotic nidus
Radial scar / complex sclerosing lesion
Differential diagnosis:
Invasive breast carcinoma (including tubular carcinoma)
Plan:
Correlate with clinical history and radiology
Examine further blocks
IPX to support Dx: CK5/6, p63 (highlight intact myoepithelial cell layer)
No specific action required for this benign diagnosis
Breast tumour with aggregates of tumour cells set within clefted spaces within the stroma. The cells show ‘reverse polarity,’ meaning that the apical surface points out, towards the cleft with the stroma.
Micropapillary breast carcinoma
Differential diagnosis:
Metastatic carcinoma (e.g. ovarian, lung, or bladder)
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, areas of differing morphology) - must be >90% of total tumour to qualify as pure micropapillary breast carcinoma
IPX to support Dx: EMA, GATA3, ER and PR, HER2, Ki67 (expect GATA3 positive, ER and PR positive. EMA shows ‘reverse polarity’)
IPX to discount DDx: PAX8 and WT1, TTF1 and Napsin A
Next steps: Synoptic report, discuss at MDT
Breast lesion with bland spindle cells arranged in short fascicles admixed with hyalinized collagen bundles and adipose tissue.
Myofibroblastoma
Differential diagnosis:
Metaplastic carcinoma
Fibromatosis
Nodular fasciitis
Spindle cell lipoma
Solitary fibrous tumour
Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for total size, relation to margins, areas of differing morphology)
IPX to support Dx: CD34, desmin, Rb (expect CD34 / desmin positive, Rb negative)
IPX to discount DDx: AE1/AE3, beta catenin, STAT6 (expect negative, no nuclear staining of beta catenin)
Pale cells scattered through epidermis over breast
Paget’s disease of nipple / breast
Differential diagnosis:
Melanoma in situ
Squamous cell carcinoma in situ
Plan:
Correlate with clinical history and radiology (?underlying breast tumour)
Examine further blocks (e.g. for underlying DCIS / carcinoma)
IPX to support Dx: CK7, HER2 (expect CK7 and HER2 positive)
IPX to discount DDx: S100 and SOX10 and Melan A, CK5/6
Advice to clinician (urgent via phone): This lesion is usually due to underlying high grade DCIS or invasive carcinoma. Patient should be urgently investigated and treated.
Breast with branching, anastomotic irregular spaces with bulbous atypical cells hobnailing into the lumen. Infiltrative growth at periphery (important in low grade lesions), high grade lesions may mimic carcinoma.
Post-radiation angiosarcoma
Differential diagnosis:
Haemangioma (if low grade)
Carcinoma (if high grade)
Plan:
Correlate with clinical history and radiology (?history of breast Ca / radiation)
Examine further blocks (e.g. for total size, relation to margins, interface to adjacent breast, areas of differing morphology)
IPX to support Dx: CD31, ERG, MYC (expect positive)
IPX to discount DDx: AE1/AE3, ER and PR (expect negative)
Next steps: Synoptic report, discuss at MDT
Breast with enlarged lobules with acini distended by eosinophilic secretions, lined by cuboidal to columnar cells with abundant foamy/vacuolated cytoplasm.
Lactating breast
Differential diagnosis:
Lactating adenoma of breast
Plan:
Correlate with clinical history and radiology (?patient pregnant ?mass lesion)
Examine further blocks
IPX to support Dx: Not required for diagnosis
No specific further action required for this benign diagnosis
