The clinical presentation is consistent with a fibroadenoma of the breast. The size and tenderness of fibroadenomas are known to fluctuate with changes in estrogen levels.
Fibroadenomas are the most common tumor in women under the age of 35 and are benign. Given its responsiveness to estrogen levels, the tumor may increase in size during lactaction or the luteal phase of the menstrual cycle. Fibroadenomas are not a precursor to malignant breast cancer. They present as small, freely movable, firm masses with well-demarcated edges.
Salzman et al. discuss the management of a palpable breast mass. They report while diagnostic mammography is usually the imaging study of choice, ultrasonography has some benefits including being more sensitive in women younger than 30 years. They recommend when any suspicious mass is detected on physical examination, a mammography or ultrasonography, it should be biopsied.
Greydanus et al. review fibroadenoma in adolescent females. They emphasize the typical biopsy reveals a pattern similar to virginal hyperplasia and male gynecomastia, with ducts that are elongated in a stroma that is fibrous.
Figure A shows hypercellular breast stroma that compresses ducts into elongated slits, a typical histological presentation of fibroadenoma.
Answer 2: Serous nipple discharge is symptomatic of intraductal papilloma, a benign breast tumor.
Answer 3: Fibroadenomas are not associated with malignant breast cancer.
Answer 4: Caseous necrosis is symptomatic of comedocarcinoma, a form of ductal carcinoma in situ (DCIS).
Answer 5: Overexpression of HER-2 receptors is common in malignant breast tumors. HER-2 is an epithelial growth factor (EGF) receptor.
Greydanus DE, Matytsina L, Gains M. Breast disorders in children and adolescents. Prim Care. 2006 Jun;33(2):455-502. Review
PMID:16713771 (Link to Abstract)
Salzman B, Fleegle S, Tully AS. Common breast problems. Am Fam Physician. 2012 Aug 15;86(4):343-9.