Main breast conditions in men

1. Gynecomastia

Gynecomastia is a very common benign condition (found in up to 55% of male breasts in autopsy series). It corresponds to breast enlargement due to the proliferation of ducts and stromal tissue, secondary to an increased estrogen-to-testosterone ratio.

The causes of these hormonal changes are numerous and often physiological in adolescents and men over 60. They can also result from endocrine disorders, certain neoplasms, systemic diseases, or medication use.

• Clinical Aspects: Gynecomastia affects 32% to 65% of the male population and occurs preferentially in cases of obesity (85% of obese patients). It more commonly presents as a unilateral mass, although it often manifests as bilateral gynecomastia with asymmetric expression. In its early and florid form, gynecomastia may be associated with painful breast tension, which gradually disappears while the palpable abnormality persists. It can be accompanied by nipple discharge in patients who show associated ductal hyperplasia on histology. All common complications linked to ductal hyperplasia, such as mastitis, lymphangitis, abscess, or fistula, may also occur in men.
• Imaging: Three radiological types of gynecomastia have been described:

1. Nodular form, corresponding to the initial florid phase: Mammography shows a homogeneous, well-defined discoid opacity, possibly with irregularities in the posterior part. Ultrasound reveals a hypoechoic subareolar mass surrounded by fatty tissue. 
2. Dendritic form, corresponding to the chronic fibrous, irreversible phase: Mammography shows an inhomogeneous triangular opacity with its apex at the retroareolar region, featuring posterior linear projections radiating into deep adipose tissue, predominantly in the upper outer quadrant. Ultrasound displays a triangular hypoechoic area centered on the nipple, with irregular posterior contours extending into echogenic fibrous breast tissue.
3. Diffuse form: This involves a global increase in breast size, which on mammography and ultrasound resembles that of a dense, heterogeneous female breast.

- Differential Diagnosis: The main differential diagnosis of gynecomastia is adipomastia (or pseudogynecomastia), which refers to fat deposits in the subcutaneous tissue. The diagnosis is most often clinical, showing bilateral breast enlargement with a soft consistency, without a palpable retro-areolar mass. Imaging typically shows the absence of radio-opaque structures.

2. Other Benign Conditions

• Benign conditions related to the lactiferous ducts and periductal tissue

• They are rare and primarily involve intraductal and intracystic papillomas.
• The imaging features are identical to those seen in women.
• Depending on the extent of the associated ductal dilation, the spread of the lesion in the ducts, and cyst formation, the ultrasound appearance can vary. In the absence of associated ductal dilation, the diagnosis is difficult
• Rare cases of diabetic mastopathy or pseudoangiomatous hyperplasia have been described. Pseudoangiomatous hyperplasia usually appears as a non-calcified, well-circumscribed mass on mammography and as a well-defined nodule, possibly hyperechoic, on ultrasound
• Lesions arising from lobules, such as fibroadenomas, fibrocystic mastopathy, or phyllodes tumors, are exceptional because the presence of mature lobules is rare in men. Certain specific contexts, such as long-term use of female hormones (transsexuality), can lead to the development of such anomalies. Their imaging appearance is identical to that described in women. Generally, a biopsy is necessary to clarify the diagnosis

• Benign conditions originating from the skin, subcutaneous tissue, vascular, lymphatic, and neural structures

• All the conditions encountered in women (lipoma, sebaceous cyst, epidermoid inclusion cyst, intramammary lymph node, capillary hemangiomas, foreign body granuloma, etc.) can also occur in men and present the same clinical signs.
• Lipoma is the second most common benign tumor in men, after gynecomastia, with epidermoid inclusion cysts in third place.

3. Male Breast Cancer

Breast cancer in men is a rare cancer, primarily affecting older patients, with a peak incidence at the age of 71.Most risk factors involve changes in the estrogen-to-androgen ratio. Thus, a high risk is found in patients with Klinefelter syndrome (relative risk of 50), testicular abnormalities, obesity, and cirrhosis. A history of thoracic radiation therapy also increases the risk of breast cancer. Although gynecomastia shares similar risk factors, it is not linked to an increased cancer risk.

There is a family predisposition, as 20% of men with breast cancer have a first-degree female relative with the disease. Genetic risk may be due to mutations in high-penetrance genes, particularly mutations in the BRCA2 gene, while the risk related to BRCA1 gene mutations is less significant

The most frequently found histological type is invasive ductal carcinoma, accounting for nearly 90% of lesions. Ductal carcinoma in situ accounts for 10% of lesions, of which 75% are of the papillary type.

Lobular carcinomas are rare (1%) due to the absence of terminal lobule differentiation in normal male breast tissue, even in cases of gynecomastia, and occur predominantly in patients with Klinefelter syndrome (XXY). More than 90% of tumors have positive hormone receptors. The prognosis with identical histology and age is similar to that of women.

- Management Guidelines

• When should a mammography be performed?

• Some authors believe that mammography is not mandatory for patients under 50 presenting with diffuse breast swelling or a non-indurated, painless, retroareolar palpable nodule.
• Others argue that it should be performed systematically, as it quickly differentiates a true pathology from simple adipomastia.
• Therefore, it is preferable to perform a mammography systematically.
• When mammography is conducted, it should be bilateral, even if symptoms are unilateral.
• If technically challenging, only an oblique view may be performed.

• When should a breast ultrasound be performed?

• Ultrasound helps confirm the benign nature of a mass identified during clinical examination by detecting glandular hypertrophy or, conversely, validating suspicious features of a mass detected on mammography.
• Therefore, it is systematically performed, except in cases of adipomastia detected on mammography.
• Ultrasound is very useful for performing biopsies and assessing the axillary region. 

• When is a biopsy necessary?

• The diagnostic value of mammography is high. If no suspicious criteria are present—such as a known genetic mutation, an eccentrically located nodule with convex posterior margins, nipple or skin retraction, or axillary lymphadenopathy—a biopsy is unnecessary.
• In all other cases, a biopsy is required. Specifically, any eccentrically located palpable mass must be biopsied.
• Finally, a centrally located mass with no identifiable cause of gynecomastia should also be sampled.