Definition/General
Introduction:
Male breast cancer is a rare disease, accounting for less than 1% of all breast cancers and less than 1% of all cancers in men
The vast majority are invasive ductal carcinomas.
Origin:
Similar to female breast cancer, it arises from the epithelial cells of the breast ducts
The terminal duct-lobular units are rudimentary in males, so lobular carcinoma is very rare.
Classification:
The histological types are similar to those in females, with invasive ductal carcinoma, no special type, being the most common (85-90%)
DCIS is also seen
Lobular carcinoma is extremely rare.
Epidemiology:
The incidence increases with age, with a peak in the late 60s and 70s
Risk factors include genetic predisposition (BRCA2 mutations), conditions causing hyperestrogenism (e.g., Klinefelter syndrome, liver disease), and radiation exposure.
Clinical Features
Presentation:
Typically presents as a painless, subareolar mass
Nipple retraction, skin ulceration, and bloody nipple discharge are more common than in females
Due to the small amount of breast tissue, it can invade the skin and chest wall earlier.
Symptoms:
A palpable lump is the most common symptom
Pain, nipple changes, and skin changes can also occur
Axillary lymphadenopathy is present in about 50% of cases at diagnosis.
Risk Factors:
BRCA2 gene mutations are a significant risk factor
Klinefelter syndrome (XXY)
Family history of breast cancer
Obesity
Chronic liver disease
Testicular conditions.
Screening:
There are no routine screening recommendations for men
Diagnosis is usually made after a man presents with symptoms
A high index of suspicion is needed for any breast mass in a male.
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Gross Description
Appearance:
Usually a firm, irregular mass located in the subareolar region
The cut surface is gray-white and gritty
Fixation to the skin or underlying muscle may be present.
Characteristics:
The tumors are often centrally located
Size is variable but they tend to be diagnosed at a slightly larger size than in females.
Size Location:
Central/subareolar location is most common
Size can range from small to large.
Multifocality:
Multifocality is uncommon.
Microscopic Description
Histological Features:
The histology is predominantly that of invasive ductal carcinoma, no special type
The tumor cells form nests, cords, and glands infiltrating a desmoplastic stroma
The features are similar to IDC in females.
Cellular Characteristics:
The tumor cells are pleomorphic with high-grade nuclei and prominent nucleoli
Mitotic figures are frequent.
Architectural Patterns:
The patterns are similar to IDC in females, including solid, cribriform, and papillary patterns
An associated DCIS component is common.
Grading Criteria:
The Nottingham grading system is used, just as in female breast cancer
Most male breast cancers are Grade 2 or 3.
Immunohistochemistry
Positive Markers:
A very high percentage of male breast cancers are positive for Estrogen Receptor (ER) and Progesterone Receptor (PR) (>90%)
Androgen Receptor (AR) is also frequently positive.
Negative Markers:
HER2 overexpression is less common than in females (about 5-15%)
Triple-negative breast cancer is rare in males.
Diagnostic Utility:
IHC is essential for determining hormone receptor and HER2 status, which guides therapy
Distinguishing from metastasis from other sites (e.g., prostate cancer with PSA) can be necessary.
Molecular Subtypes:
The vast majority of male breast cancers are of the Luminal A or Luminal B subtypes.
Molecular/Genetic
Genetic Mutations:
BRCA2 mutations are found in about 10-15% of cases
BRCA1 mutations are less common
PALB2 is another important susceptibility gene
Somatic mutations in PIK3CA and TP53 are also found.
Molecular Markers:
The genomic landscape is similar to that of ER-positive female breast cancer.
Prognostic Significance:
The prognosis is generally similar to that of female breast cancer when matched for stage
However, men are often diagnosed at a later stage, which contributes to a worse overall outcome
Lymph node status is the most important prognostic factor.
Therapeutic Targets:
Endocrine therapy (tamoxifen is the standard of care) is the mainstay of treatment due to high ER/PR positivity
Chemotherapy and radiation are used based on stage and risk factors
HER2-targeted therapy is used for HER2-positive cases.
Differential Diagnosis
Similar Entities:
Gynecomastia
Metastatic carcinoma (e.g., from prostate, lung)
Benign breast lesions (rare in men).
Distinguishing Features:
Gynecomastia shows ductal hyperplasia without atypia and a characteristic periductal stromal proliferation
Metastatic tumors will have a different IHC profile (e.g., PSA positive for prostate cancer).
Diagnostic Challenges:
The main challenge is the low index of suspicion for breast cancer in men, leading to delayed diagnosis
Differentiating from gynecomastia with atypia can sometimes be difficult on small biopsies.
Rare Variants:
Papillary carcinoma is a relatively more common special subtype in men compared to women
Lobular, medullary, and mucinous carcinomas are very rare.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[specimen type], measuring [size] cm in greatest dimension
Diagnosis
[diagnosis name]
Classification
Classification: [classification system] [grade/type]
Histological Features
Shows [architectural pattern] with [nuclear features] and [mitotic activity]
Size and Extent
Size: [X] cm, extent: [local/regional/metastatic]
Margins
Margins are [involved/uninvolved] with closest margin [X] mm
Lymphovascular Invasion
Lymphovascular invasion: [present/absent]
Lymph Node Status
Lymph nodes: [X] positive out of [X] examined
Special Studies
IHC: [marker]: [result]
Molecular: [test]: [result]
[other study]: [result]
Final Diagnosis
Final diagnosis: [complete diagnosis]