Slide Description: This is a benign tumor of the breast. It is much more frequent in women 30 to 40 years of age, and is usually located in the upper outer quadrant; it is firm and freely movable, i.e., not attached to the skin. This tumor consists of fibrous connective tissue which distorts the glands which are normal and not neoplastic. It's not truly a fibroadenoma because the glandular tissue is not neoplastic, only the fibrous connective tissue is.

IMDEPSAASIAC:

Identify: breast (?)

Morphology: Proliferation of fibrous tissue distorts the glandular tissue elements.

Disease: Benign neoplasm of the breast.

Etiology (main): unknown

Pathogenic mechanism: Fibroadenomas are benign tumors that represent a hyperplastic or proliferative process in a single terminal ductal unit. Approximately 10% of fibroadenomas disappear each year, and most stop growing after they reach 2-3 cm

Structural changes (specific, gross, and micro): Proliferation of connective tissue seen as in the middle of the slide distorting the appearance of the glandular tissue.

Are there any other sites of involvement in the body? Confined to the breast

Are there any other diseases where similar changes can be seen? Cysts, papilloma, carcinoma, lipoma

Signs / Symptoms: Small (~1in), oval, rubbery mass, moveable within the breast tissue.

Investigations (confirmation / gauge extent): Ultrasonography for patients younger than 30 or pregnant. Mammography and US for those older than 30. Biopsy.

Are there any other diseases you have studied where such tests can be positive?

Course of disease progress (complications, monitoring, outcome): Benign with extremely small chance of malignancy. Surgical excision or leaving as is are acceptable courses of treatment.

Highlight 3 important points:

1. Fibroadenomas are the most common type of breast lesion for women of all ages within the reproductive years.

2. Fibroadenomas are benign, unlike carcinomas which are malignant. After menopause they will usually regress. Once benign always benign.

3. They rarely appear in women post menopause so suspect a malignancy in women who are post menopausal and present with a new solid lesion.

Lab Questions:

1. Give an example of a mixed tumor

Mixed tumors consist of elements from a single stem cell line with divergent differentiation. A classic example is a salivary gland tumor called pleomorphic adenoma. These have epithelial components in addition to a fibromyxoid stroma. Additionally there may be islands of cartilage or bone. The elements are derived from epithelial cells, myoepithelial cells, or both in the salivary glands.

Don't confuse this with a teratoma which contains recognizable mature or immature cells / tissues of more than one germ-cell layer.

Mixed tumor: mixed elements of epithelial and mesenchymal cell lines, starting from one specific cell line.

2. Name neoplasms that are hormone dependent

Fibroadenomas seem to exhibit hormone dependence given they regress post menopause.

Leiomyomas of the uterus are influenced by the circulating levels of estrogens. Increase rapidly in size during pregnancy and cease growing or atrophy after menopause.

Vignette

Your 26 year old female patient tells you she found a painless lump in her breast while checking herself the other day. She's concerned it could be a carcinoma. She has no family history of breast cancer. On palpation you find a small, moveable, oval shaped, rubber-like lesion in the right upper quadrant of her left breast. You order an ultrasonography, followed by an image-guided biopsy. The lesion is diagnosed as a fibroadenoma. You inform the patient that the lesion is benign and that it will regress with time, but to return if the lump enlarges or becomes painful.