Fibroadenoma

Fearsome
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Diagnosis and reasoning

A palpable lesion of the breast is a frequent discovery in young women of the reproductive age; in general, benign breast diseases (BBD) are more plausible than cancer in this group of patients. Key BBDs to consider in this respect include fibrocystic change, sebaceous cysts, fibroadenomas, phyllodes tumors, ductal ectasia, intraductal papillomas, trauma, and infection. The assessment of any breast lump comprises a 'Triple Test', which includes clinical evaluation and imaging (mammography or breast ultrasound), corroborated by pathological evidence in the form of fine-needle aspiration cytology (FNAC), with or without a Tru-Cut biopsy. Here, our patient's family history is negative for breast malignancies, and her physical reveals a discrete, smooth, rubbery, widely mobile, and non-tender lump. These findings suggest a benign etiology. In particular, the mobility of the lump is particularly suggestive of a fibroadenoma, sometimes called a 'breast mouse' owing to this feature. Breast imaging is the second step of the triple test. In young women, the increased density of breast tissue makes mammography difficult to interpret, making ultrasound the modality of choice. This patient's scan shows a well-circumscribed, oval, solid mass measuring 1.7x2.2 cm, with a sharp, smooth contour and uniform hypoechogenicity; this too is compatible with a fibroadenoma. FNAC, which can be performed concurrently with an ultrasound, reveals abundant bare bipolar stromal nuclei surrounding sheets of metachromatic epithelial cells arranged in an antler-like pattern, confirming the clinical diagnosis. A Tru-Cut biopsy should be avoided; performing unnecessary biopsies for benign conditions poses a higher risk of developing a malignancy in the future. As mentioned earlier, fibroadenomas are benign and can be managed via observation, with periodic clinical evaluations at six-monthly intervals to detect any change in size or consistency of the tumor. However, it is still important to offer excision of the lump to the patient concerned, in view of her peace of mind; many such women do opt for removal. Note that mastectomy, radiotherapy, and chemotherapy are mainly reserved for malignant breast disease.


Discussion

A fibroadenoma is a benign breast neoplasm arising from the terminal duct-lobular unit, which is composed of both stromal and epithelial elements. It is the most common benign breast neoplasm, with a reported incidence of 7-13% in females; adolescents and young women of 20-30 years of age are most commonly affected. Fibroadenomas are thought to be the result of aberrant breast growth, classifying them as hyperplastic lesions rather than true neoplasms. They usually form during menarche, a time when hyperplastic lobules are frequent and both the stromal and epithelial cells are proliferating. Additionally, these tumors are stimulated by estrogen and progesterone; they may fluctuate in size throughout the menstrual cycle, becoming larger during pregnancy and lactation and undergoing atrophic changes during menopause. Although no genetic factors are currently linked to their onset, patients with multiple tumors often have a positive family history for breast cancer. Hormonal influences, particularly estrogen levels, seem to play a role in their development. The age of menarche, menopause, and hormonal therapy have not been implicated as risk factors. Body mass index and the number of full-term pregnancies, as well as consumption of large quantities of vitamin C and cigarette smoking all seem to be associated with a reduced risk. In most cases, a fibroadenoma is detected incidentally during a medical examination or self-examination as a solitary breast lump. The lump is typically discrete with clearly defined edges, smooth, rubbery, mobile, and non-tender. The right breast and the upper outer quadrants are statistically more commonly involved. Ten to twenty-five percent of patients develop multiple fibroadenomas, which may present simultaneously or be discovered over several years. Giant fibroadenomas (7-8%) are those that measure >5cm in diameter or are disproportionately larger than the normal breast tissue. Adult presentations are usually encountered in pregnant or lactating women. The rarer, juvenile type affects prepubertal girls, presenting as a rapidly growing mass that causes asymmetry of the breast, distortion of the overlying skin, and stretching of the nipple. A 'triple test,' which includes a clinical evaluation and imaging corroborated by pathological evidence in the form of fine-needle aspiration cytology (FNAC), with or without biopsy, is key in the assessment of these patients. As the condition is often encountered in young women, the increased density of the breast tissue makes mammography difficult to interpret. Therefore, ultrasound of the breast and axilla combined with FNAC is the diagnostic modality of choice. It is preferable to avoid biopsies, since women who undergo biopsies for benign conditions appear to be at a higher risk of developing a breast malignancy in the future. However, in the event that a biopsy is performed, fibroadenomas can be classified as either simple or complex, based on histological findings. Complex fibroadenomas, unlike their simple counterparts, contain elements of cysts, sclerosis, adenosis, epithelial calcifications, or papillary apocrine metaplasia. Younger patients with a simple fibroadenoma and no family history of breast cancer should simply be observed with regular follow-up examinations, usually every 6 months, in order to detect any changes in the size or consistency of the mass. This is because the risk of malignant transformation is low, and because a substantial percentage of lesion undergo spontaneous regression or resolution; thus, the risk of unbecoming scarring or extensive ductal damage due to surgery outweighs the benefits. However, surgery may be considered if the patient is experiencing anxiety because of the mass and strongly wishes to have it removed. Furthermore, a fibroadenoma that expands over time or persists beyond the age of 35 should be surgically removed; likewise, when a fibroadenoma is detected in a woman older than 35 years old, it should be immediately excised and samples sent for biopsy. While juvenile giant fibroadenomas should be removed immediately as they may distort the shape of the breast, giant fibroadenomas in an adult of reproductive age often get smaller towards the end of the lactation period, and surgery should be delayed until the patient's hormonal status has returned to the baseline. Malignant transformation of a fibroadenoma is rare, with a reported incidence of 0.002-0.0125%. A minimally increased risk of malignancy has been established in women with fibroadenomas, as compared to the general population. Middle-aged women with associated risk factors, such as a strong family history of breast cancer, a complex fibroadenoma, or proliferative changes in the adjacent parenchyma, are the most affected. Overall, fibroadenomas resolve spontaneously within five years in approximately 50% of women; most vanish after 15 years. Only about 25% grow during the follow-up period, requiring surgery.


Take home messages

  1. Fibroadenomas are the most common benign breast neoplasms; adolescents and young women are most commonly affected.
  2. In most cases, fibroadenomas are detected incidentally as a discrete, solitary, breast lumps, with clearly defined edges.
  3. Given the young age at presentation, the assessment includes a clinical evaluation with an ultrasound of the breast and axilla combined with FNAC; unnecessary biopsies are better avoided.
  4. Younger patients with a simple fibroadenoma and no family history of breast cancer should be observed, while a fibroadenoma that expands over time or persists beyond the age of 35 should be surgically removed.
  5. Malignant transformation is rare; a minimally increased risk of malignancy has been established.

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