Breast Abnormalities

Background

Normal breast tissue begins to develop at 5 weeks gestation, deriving from the ectoderm, and lactiferous ducts begin to develop by 20 weeks. Breast tissue is palpable in the neonate for up to 6-12 months. With the onset of thelarche, estrogen stimulation promotes growth of ducts and fat, while progesterone promotes lobular and alveolar budding.

Most breast conditions arising in the pediatric population are benign, and in most cases a conservative approach is taken in their management. Diagnosis and treatment must be focused on avoiding damage to developing breast tissue. 

 

Congenital Breast Abnormalities

  1. Nipple abnormality
  2. Breast tissue abnormality
    • Polymastia. Female preponderance, accessory breast is most commonly found at the axilla. Usually asymptomatic and diagnosed at puberty or during pregnancy. Surgery is usually avoided due to high incidence of postoperative complications.
    • Assymetry is defined as unilateral aplasia or hypoplasia of breast tissue. This can be associated with a defect in one or both pectoral muscles.
    • Amastia is complete absence of both breast tissue and the nipple-areola complex (vs. amasia, absence of breast tissue only). This is due to regression or failure to develop the mammary ridge. It is often associated with other ectodermal defects, including cleft palate.
  3. Chest wall deformity
  • Poland's syndrome: unilateral chest wall hypoplasia with ipsilateral upper limb deformity. Three times more common in males. Due to hypoplasia of subclavian artery during embryogenesis, leading to agenesis of the pectoral muscles and rib cage abnormalities.
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  • Anterior thoracic hypoplasia: very rare. Characterized by posterior displacement of ribs, anteriorly sunken chest wall, and hypoplasia of the ipsilateral breast. Sternum and pectoral muscles are normal.

 

Prepubertal Breast Abnormalities

  1. Premature thelarchy: development of breast buds before 7.5 years of age in girls.
  2. Gynecomastia: excessive development of breast tissue in male patients. This is physiologic in three age groups - neonates (due to transplacental passage of estrogen), pubertal boys, and elderly men. Pathologic gynecomastia results from increased estrogen production (i.e. Leydig cell tumor), or decreased testosterone production (i.e. viral orchitis). Medications like ketoconazole can displace estrogen from sex-hormone binding globulin.

 

Postpubertal Breast Abnormalities

  1. Infection (mastoiditis, abscess). Bimodal distribution with most cases presenting younger than 2 months or 8-17 years. Most cases are in female patients. Most common pathogens are S. aureus (>75% of cases), gram-negative bacilli, group A Streptococcus, and Enterococcus.
  2. Galactocoele: a cystic collection of breast milk. Usually found in lactating women, rare in children. Prolactin stimulation and ductal obstruction are thought to play a role in pathogenesis. Treatment is usually conservative, with aspiration for symptomatic relief.
  3. Neoplasm (benign). Mammography does not play a role in diagnosis due to the increased density of young breast tissue, and the risks of radiation exposure. Early life exposures play a great role in benign breast disease. Risk factors for development of benign breast disease include high BMI, high-fat diet, and alcohol consumption during adolescence.
    • Fibroadenoma. Comprises 91% of all solid breast masses in girls younger than 19 years. Estrogen-sensitive, painless rubbery masses that are hypechoic on ultrasound. They can be complicated cysts, calcifications, or apocrine metaplasia. Patients with complex fibroadenoma are at slightly greater risk for breast cancer.
    • Juvenile fibroadenoma. An uncommon variant that is seen more commonly in African-American populations. Generally, excision is indicated.
    • Pseudoangiomatous Stromal Hyperplasia (PASH). Benign proliferation of breast stroma with channels ligned by thin spindle cells. Thought to be due to an exaggerated response from estrogen-primed breast tissue to progesterone. Generally managed conservatively with serial imaging.
    • Juvenile papillomatosis. Presents similarly to fibroadenoma, but on ultrasound these lesions are heterogenous with a "Swiss cheese" like appearance. These patients will have a higher risk for breast cancer, so they must be monitored closely.
  4. Neoplasm (malignant). Because ultrasound is not useful in predicting histopathologic diagnosis, lesions that are suspicious for malignancy warrant a fine needle aspiration (FNA) and possible biopsy.
  • Phyllodes tumor. The most common breast malignancy in adolescents. Like fibroadenomas, it arises from the lobular tissue. Degree of malignancy can be predicted by sarcomatous elements, infiltrative margins, and stromal cell atypia. Because imaging and  FNA do not distinguish between benign and malignant forms, ultrasound-guided core needle biopsy is indicated in the management of these patients.
  • Metastases are more common than primary breast cancers. Lymphoma, leukemia, and rhabdomyosarcoma are the most common primary tumors that metastasize to the breast.
  • Primary breast carcinoma comprises <1% of childhood breast cancers. These are usually secretory, which are less invasive than ductal carcinoma.

 

References

  1. Diamantopoulos, S., and Bao, Y. (2007). Gynecomastia and premature thelarche: a guide for practitioners. Pediatrics in Review, 28(9), 57-68.
  2. Frazier, A.L. and Rosenburg, S.M. (2012). Preadolescent and adolescent risk factors for benign breast diseaseJ Adolescent Health, 52(5), S36-S40.
  3. Kulkarni, D. and Dixon, J.M. (2012). Congenital breast lesionsWomen's Health, 8(1), 75-88.
  4. Kaneda, H.J., et. al. (2012). Pediatric and adolescent breast masses: a review of pathophysiology, imaging, diagnosis, and treatment. Am J Roentgenol, 200, 204-212.
  5. Liu, Y., et. al. (2012). Intakes of alcohol and folate during adolescence and risk of proliferative benign breast diseasePediatrics, 129(5), 1192-1198.
  6. Rogers, D.A., et. al. (1994). Breast malignancy in children. Pediatr Surg, 29(1), 48-51.
  7. Vade, A., et. al. (2008). Role of breast sonography in imaging of adolescents with palpable breast massesAm J Roentgenol, 191(3), 659-663.

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