Male Breast Cancer

Slide 1 · Male Breast Cancer

Pathogenesis · Morphology · Clinicopathologic correlation

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Recognize

Relate male ductal anatomy to clinical presentation.

Explain

Assess familial, hormonal and environmental risk factors.

Diagnose

Interpret morphology, grade and ER/PR/HER2 profiles.

Integrate

Explain regional spread, prognosis and treatment logic.

Slide 3 · Male breast: The substrate for carcinoma

Schematic

Male breast cross-section

Skin

Chest wall

Why location matters

Male breast epithelium is concentrated in relatively large ducts close to the nipple.

Diagnostic implication

This duct-centered anatomy helps explain the usual subareolar presentation.

Slide 4 · Ducts predominate; Lobules are sparse

The normal breast contains major ducts, branching ducts and terminal lobular units.

In males, epithelial tissue remains mainly in the large ducts near the nipple.

Lobules are generally undeveloped in the male breast.

The anatomic substrate helps explain why duct-type carcinomas dominate.

Slide 5 · Anatomic explanation of the central mass

Schematic

Duct-rich area

Major ducts beneath the nipple

Tumor origin

Malignant epithelial proliferation

Limited space

Close to skin and chest wall

Clinical finding

Palpable subareolar mass

The site of origin contributes directly to the presenting clinical pattern.

Slide 6 · Male breast cancer is uncommon

1 of 100

Male incidence as ~1% of female incidence.

Slide 7 · Population lifetime risk remains low

0.13%

Reported lifetime risk in males

Interpretation

Population risk is small; An affected first-degree relative or pathogenic germline variant changes individual risk.

Slide 8 · U.S. Burden: Textbook estimate for 2025

2,800

Estimated U.S. New male cases in 2025

510

Estimated U.S. Male breast-cancer deaths in 2025

A historical estimate quoted by Robbins, not a 2026 surveillance update.

Slide 9 · Risk-factor categories

Demographic

Increasing age; Western-country residence

Familial

First-degree affected relative; Inherited predisposition

Hormonal / metabolic

Exogenous estrogen, obesity, infertility

Exposure / history

Radiation, alcohol, prior benign breast disease

Slide 10 · Increasing age is an important risk factor

Older age among the leading epidemiologic associations.

A new breast mass in an older male should not be assumed benign.

Age is a risk factor—not a diagnostic criterion.

Interpret the age effect together with family history and examination.

Slide 11 · Family history changes the prior probability

A first-degree relative with breast cancer is a recognized risk factor.

Family history should include breast cancer in female and male relatives.

A pathogenic familial susceptibility variant may be present.

Absence of a striking family history does not exclude a hereditary cause.

Slide 12 · BRCA2 is the major familial susceptibility gene

~6%

Male BRCA2 carriers developing breast cancer (as reported by Robbins)

Important denominator

This is risk among male carriers—not the proportion of male tumors caused by BRCA2.

Slide 13 · BRCA2 prevalence varies across cohorts

4%–40%

Reported BRCA2 germline mutation frequency among male breast-cancer cases

Sampling matters

Robbins explicitly attributes this wide range to the population tested.

Slide 14 · Other inherited susceptibility genes

BRCA1

Increased risk, lower than with BRCA2

PALB2

Higher-than-baseline susceptibility

PTEN

A lower-risk association in the male context

TP53

A lower-risk association in the male context

Slide 15 · BRCA2 and homologous recombination repair

Schematic

BRCA2 function

Supports repair of double-strand breaks

Pathogenic variant

Impaired homologous recombination

Genome instability

DNA damage and mutations accumulate

Susceptibility

Breast carcinoma risk increases

Mechanistic association; Progression is not deterministic for every carrier.

Slide 16 · Keep two BRCA2 denominators separate

Risk among male BRCA2 carriers: Approximately 6% develop breast cancer.

Prevalence among affected male cases: 4%–40% depending on cohort.

These figures answer different epidemiologic questions.

Neither estimate can be substituted for the other.

Slide 17 · Exogenous estrogens and hormonal milieu

Exposure to exogenous estrogens is a textbook-listed risk factor.

An estrogen– androgen imbalance also contributes to gynecomastia.

Hormonal effects and malignancy risk are different clinical concepts.

An enlarged breast is not, by itself, proof of carcinoma.

Slide 18 · Obesity and infertility in the risk profile

Obesity among male breast cancer risk factors.

Infertility is also included as an epidemiologic association.

These factors should be documented within a complete risk assessment.

They are neither necessary nor sufficient for cancer development.

Slide 19 · Klinefelter syndrome: Two related findings

Benign breast enlargement

Klinefelter syndrome may be associated with gynecomastia.

Cancer predisposition

Klinefelter syndrome is listed among male breast cancer risk factors.

Slide 20 · Radiation and other external exposures

Prior ionizing-radiation exposure appears’ risk-factor list.

Alcohol consumption is also associated with male breast cancer risk.

A careful exposure history is relevant to risk characterization.

An exposure history cannot establish a diagnosis without tissue evaluation.

Slide 21 · Additional epidemiologic associations

Prior benign breast disease is listed as a risk factor by Robbins.

Western-country residence is another reported association.

These are group-level associations; They do not define causality for an individual.

Clinical suspicion still depends on presentation and examination.

Slide 22 · Risk assessment: Document the right history

Domain

Specific questions

Clinical relevance

Familial

First-degree affected relative; known BRCA2 variant

Identifies inherited susceptibility

Hormonal

Estrogen exposure; infertility; Klinefelter syndrome

Relevant endocrine background

Exposure

Chest irradiation; alcohol

Potential environmental factors

Metabolic / age

Age; obesity; benign breast history

Modifies risk context

Slide 23 · Clinical application: Susceptibility

Teaching vignette — hypothetical

A 63-year-old man with a firm breast lesion reports that his sister was diagnosed with breast cancer and his father carried a pathogenic BRCA2 variant.

Which aspect of his history is most important to integrate with the biopsy findings?

Slide 24 · Risk vignette: Interpretation

A known familial BRCA2 pathogenic variant is a major inherited susceptibility clue.

First-degree breast-cancer family history independently reinforces concern.

The lesion still requires standard diagnostic assessment.

A risk factor informs prior probability; It does not replace pathology.

Slide 25 · The dominant cancer is invasive NST

>90%

Invasive carcinoma of no special type

Characteristic phenotype

Typically ER-positive, PR-positive and HER2-negative.

Slide 26 · Special histologic types are exceptional

<5%

Special histologic types collectively (Robbins)

Diagnosis

Do not assume that every unusual architecture represents a special histologic type; Classification requires morphology.

Slide 27 · Hormone-receptor pattern of the usual tumor

The dominant male subtype as ER-positive.

Progesterone receptor is also generally expressed.

HER2 negativity is characteristic of this dominant category.

Each tumor requires individual testing; The population pattern is not a substitute.

Slide 28 · Why invasive lobular carcinoma is unusual

Lobular carcinoma ordinarily relates to breast lobular differentiation.

Male breast epithelium is mainly confined to large ducts.

The very limited lobular apparatus helps explain rarity of lobular carcinoma.

A genuine special subtype remains possible, but needs morphologic confirmation.

Slide 29 · Central location drives the clinical pattern

Schematic

Male breast cross-section

Skin

Chest wall

Subareolar tumor

Why location matters

The usual malignant mass arises near large ducts beneath the nipple.

Diagnostic implication

Even a small tumor can abut the skin and chest-wall structures.

Slide 30 · Palpable mass: The canonical presentation

The primary clinical presentation is a palpable subareolar mass.

Typical tumor size at presentation as 2–3 cm.

A new firm unilateral lesion must not be dismissed as physiologic enlargement.

Local examination includes the nipple, skin and regional nodes.

Slide 31 · Nipple discharge is another presenting clue

Nipple discharge may accompany male breast carcinoma.

A central ductal lesion can communicate with the nipple apparatus.

A discharge complaint needs assessment in the context of a mass and examination.

The symptom alone does not determine histologic type.

Slide 32 · Skin invasion can occur in a small tumor

Schematic

Central carcinoma

Subareolar epithelial origin

Short distance

Little tissue between tumor and skin

Local extension

Dermis becomes involved

Visible consequence

Ulceration or skin change

The apparent size of a mass need not reflect its potential for local extension.

Slide 33 · Close chest-wall relationship matters

The male breast offers little separation from the underlying thoracic wall.

Relatively small cancers may reach adjacent deep structures.

Chest-wall invasion is a staging-relevant feature.

Local extension should be documented separately from tumor size.

Slide 34 · Gross appearance of invasive carcinoma NST

The parent section describes a hard, irregular mass as a common gross pattern.

An exuberant desmoplastic response produces dense fibrous stroma.

Gross boundaries may be less clear than the palpated mass.

These are general invasive NST features, not a male-specific diagnostic signature.

Slide 35 · What histologic invasion means

Schematic

Intact duct

Carcinoma confined within the duct remains bounded by the epithelial–stromal interface.

Invasive cancer

Malignant epithelial cells extend beyond the ductal boundary into surrounding tissue.

Conceptual diagram, not a histologic specimen

Slide 36 · Microscopic morphology of invasive NST

Invasive malignant epithelial glands, nests or sheets infiltrate stroma.

A desmoplastic reaction may dominate the surrounding tissue.

Architecture varies with tumor differentiation.

Morphology establishes subtype; ER/PR/HER2 describe treatment-relevant biology.

Slide 37 · Grade: Tubule formation

Well-differentiated tumors retain substantial glandular differentiation.

Poorly differentiated tumors form fewer recognizable tubules.

The degree of tubule formation contributes to Nottingham grade.

Tumor type and grade are related but separate observations.

Slide 38 · Grade: Nuclear pleomorphism

Lower-grade tumors have more uniform nuclear morphology.

Higher-grade tumors show larger, irregular and more variable nuclei.

Nuclear appearance is scored separately from glandular formation.

This is a microscopy-based assessment, not a biomarker assay.

Slide 39 · Grade: Mitotic activity

Mitotic activity reflects cellular proliferation in tumor tissue.

Grade 3 carcinomas characteristically show more mitotic figures.

Necrosis may accompany highly proliferative, poorly differentiated cancers.

A high mitotic rate is not interchangeable with HER2 positivity.

Slide 40 · Nottingham grading combines three features

Schematic

Tubule formation

Loss of glandular differentiation

Nuclear pleomorphism

Variation in nuclear size and shape

Mitotic activity

Proliferative activity in tumor cells

Nottingham histologic grade

Slide 41 · Three core predictive biomarkers

Schematic

ER

Nuclear receptor

Endocrine therapy

PR

Nuclear receptor

Hormone-signaling context

HER2

Cell-surface receptor

HER2-directed therapy

Tumor biology guides treatment selection; Phenotype must be measured, not inferred.

Slide 42 · ER assessment: A nuclear IHC biomarker

ER immunohistochemistry detects nuclear receptor expression.

The parent section defines ER positivity as at least 1% of tumor nuclei staining.

ER predicts likelihood of benefit from endocrine therapy.

The dominant male subtype is ER-positive, but results must be reported per tumor.

Slide 43 · PR expression supplies additional context

PR expression is usually assessed by nuclear immunohistochemistry.

ER-positive carcinomas frequently coexpress PR.

Low PR expression can be associated with less favorable outcomes in ER-positive disease.

Receptor results should be interpreted as a panel, not as isolated labels.

Slide 44 · HER2 testing: Protein and amplification

HER2 is assessed using membrane immunohistochemistry.

In situ hybridization can evaluate HER2 gene amplification.

HER2 positivity has important predictive implications for targeted agents.

Most male cancers are HER2-negative.

Slide 45 · Biomarker roles are not interchangeable

Measure

What it contributes

Why it matters

ER

Tumor endocrine phenotype

Predicts endocrine treatment sensitivity

PR

Additional hormone receptor information

Refines interpretation of ER-positive cancers

HER2

Growth-receptor status

Predicts HER2-targeted therapy benefit

Grade

Tumor differentiation and proliferation

Prognostic tumor biology information

Slide 46 · Gynecomastia: A common benign mimic

Gynecomastia is the most frequent benign lesion in the male breast.

It typically presents as button-like subareolar enlargement.

The enlargement may be unilateral or bilateral.

It reflects relative estrogenic effects rather than malignant epithelial invasion.

Slide 47 · Gynecomastia: Ductal hyperplasia and fibrosis

Histology shows increased duct lining epithelial cells.

Dense collagenous connective tissue accompanies the epithelial proliferation.

Lobules are almost never formed.

These features differ fundamentally from infiltrating malignant glands.

Slide 48 · Benign proliferation versus stromal invasion

Schematic

Benign enlargement

Increased ductal epithelium and connective tissue; Almost no lobule formation.

Invasive malignancy

Atypical cells infiltrate tissue outside normal duct boundaries.

Gynecomastia: Schematic

Carcinoma: Schematic

Slide 49 · Male subareolar lesion: Clinical distinction

Feature

Gynecomastia

Invasive carcinoma

Typical pattern

Button-like subareolar enlargement

Palpable discrete subareolar mass

Tissue process

Benign ductal and stromal proliferation

Infiltrative epithelial malignancy

Nipple / skin

Not defining in source

Discharge and possible ulceration

Regional spread

Not expected for benign process

Axillary nodes may be involved

Slide 50 · Microscopic distinction: The decisive boundary

Histologic parameter

Gynecomastia

Invasive carcinoma NST

Ductal epithelium

Hyperplastic, within ducts

Malignant cells breach normal compartments

Surrounding stroma

Increased collagen

May show desmoplasia with infiltrating tumor

Tumor differentiation

No malignant carcinoma grading

Nottingham grade is applicable

Clinical interpretation

Benign lesion

Requires stage and receptor evaluation

Slide 51 · From suspicious mass to pathologic diagnosis

Schematic

Suspicious finding

Unilateral firm mass or suspicious nipple change

Tissue diagnosis

Core biopsy when clinically indicated

Biologic work-up

Type, grade, ER/PR/HER2

Extent assessment

Primary, nodes, distant disease

Exact investigation sequence depends on clinical findings and institutional pathways.

Slide 52 · Core biopsy and pathologic work-up

A suspicious male breast lesion requires tissue confirmation.

Core biopsy permits classification of invasive versus noninvasive disease.

Histologic type and grade are evaluated on tumor tissue.

ER, PR and HER2 should be assessed for invasive carcinoma.

Slide 53 · Regional spread: The axilla is critical

The male cancer dissemination pattern parallels that of female breast cancer.

Axillary lymph nodes are a major regional site of spread.

Regional nodal status is important for staging and prognosis.

Lymph-node involvement does not itself mean distant metastasis.

Slide 54 · About half have axillary nodal involvement

~50%

Axillary lymph-node involvement at presentation

Stage is central

Regional nodal involvement affects stage and prognosis; It is not proof of distant metastasis.

Slide 55 · Distant metastatic distribution

Schematic

Breast primary tumor

Axillary regional nodes

Lung

Brain

Bone

Liver

Slide 56 · Staging separates tumor, nodes and metastasis

Schematic

T — Primary tumor

Size / local tissue invasion

N — Regional nodes

Axillary and regional spread

M — Distant metastasis

Beyond regional nodal basin

TNM anatomic staging is combined with grade and receptor biology in prognostic staging.

Slide 57 · Small size does not eliminate local risk

A small subareolar carcinoma may contact overlying skin early.

Skin ulceration or chest-wall invasion reflects local extent.

Tumor dimension and adjacent-structure invasion must both be assessed.

Nodal and distant disease are recorded as separate staging components.

Slide 58 · Males often present at a higher stage

Males tend to have more advanced stage at presentation.

The central location and proximity to adjacent tissues can complicate local extent.

Nodal involvement is frequent at initial diagnosis.

Comparing outcomes requires stage adjustment.

Slide 59 · Stage-matched prognosis: Important nuance

Outcomes similar to females after matching for stage.

A higher stage distribution at diagnosis is not identical to intrinsically worse biology.

Prognosis depends on stage and tumor biology.

Avoid comparing unadjusted groups as if their stage distributions were equal.

Slide 60 · Separate prognostic from predictive variables

Variable

Chief role

Interpretation

Distant metastasis

Prognostic

Strong determinant of outcome

Axillary nodal status

Prognostic

Regional disease burden

Grade

Prognostic

Differentiation and proliferative behavior

ER / HER2

Predictive and prognostic

Guides endocrine / targeted therapy

Slide 61 · Local treatment description

Mastectomy as the usual local surgical approach.

Its text also mentions axillary node dissection in male cases.

Management must address tumor extent and regional nodal disease.

This textbook statement should not be interpreted as a universal 2026 axillary surgical mandate.

Slide 62 · Systemic treatment follows tumor biology

Schematic

Confirm carcinoma

Type and grade

Profile tumor

ER, PR, HER2

Stage disease

Local / regional / distant extent

Select therapy

Biology- and stage-informed plan

Broadly comparable systemic treatment principles in males and females.

Slide 63 · Why endocrine treatment is relevant

The dominant male phenotype expresses ER and PR.

Endocrine treatments interfere with estrogen receptor signaling.

Endocrine therapy as central for luminal breast carcinomas.

Treatment choice depends on clinical setting and patient-level evaluation.

Slide 64 · BRCA-associated cancers: Therapeutic context

Schematic

BRCA dysfunction

Homologous recombination impairment

Repair vulnerability

DNA lesions become harder to repair

Therapy concept

PARP inhibitor sensitivity in selected settings

The parent treatment table links germline BRCA1/2 alterations to PARP inhibitor response.

Slide 65 · Therapeutic target and diagnostic assay

Target / pathway

Laboratory test

General treatment concept

ER

Nuclear ER IHC

Endocrine blockade or deprivation

HER2

HER2 IHC; ISH amplification

HER2-directed therapy when positive

BRCA1 / BRCA2 HRR

Germline mutation testing

DNA-repair-directed strategies in eligible patients

Slide 66 · Case application: Subareolar mass

Teaching vignette — hypothetical

A 70-year-old man presents with a unilateral firm subareolar 2.5-cm mass, intermittent nipple discharge and ipsilateral palpable axillary nodes.

What three disease dimensions should pathology and staging establish?

Slide 67 · Case discussion: Histology, phenotype, extent

Histology: Establish whether an invasive carcinoma of NST or another lesion is present.

Phenotype: Determine ER, PR and HER2 status; Assign grade when indicated.

Extent: Evaluate primary tumor, regional nodes and distant spread.

Clinical suspicion and nodal examination cannot replace histopathologic diagnosis.

Slide 68 · Case application: Stage and outcome

Teaching vignette — hypothetical

Two men have ER-positive/HER2-negative invasive NST. One has a localized lesion; The other has axillary nodal involvement and skin ulceration.

Why is receptor concordance insufficient to predict equivalent prognosis?

Slide 69 · Case discussion: Biology is not stage

Shared ER/HER2 phenotype does not equal shared anatomic extent.

Regional nodes and skin involvement modify stage and prognosis.

Histologic grade may further distinguish tumor behavior.

Interpret comparisons after considering disease stage—not sex alone.

Slide 70 · Core clinicopathologic conclusions

Rare but consequential

Male risk is low, but new suspicious lesions need evaluation.

Genetic signal

BRCA2 is the leading familial predisposition highlighted by Robbins.

Anatomic pattern

Large central ducts explain the dominant subareolar presentation.

Tumor phenotype

Invasive NST with ER/PR positivity and HER2 negativity predominates.

Extent determines much

Axillary nodes and local invasion are common at presentation.

Stage is essential

Stage-matched male and female outcomes are reported as similar.

Slide 71 · Selected sources

Primary textbook

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th ed. (2026). Chapter 23: The Breast; pp. 944–967. Main male breast cancer section: p. 966.

Supplemental clinical guidance

National Cancer Institute. Male Breast Cancer Treatment (PDQ®), Health Professional Version. Used for general diagnostic-workup context; Robbins remains the primary content source.