The discovery of a breast mass in an adolescent female understandably awakens concern in both the patient and her family. Fortunately, the majority of breast masses in this age group are benign, with fibroadenoma being the most common lesion identified. However, malignant tumors may occur on rare occasions, making accurate diagnosis of the newly discovered breast mass critically important in the adolescent population.

A fibroadenoma is a benign estrogen sensitive tumor that is identified in 70% to 95% of breast biopsy specimens in adolescent females. Their peak incidence is in late adolescence until the early 20s, though premen- archal cases have been described. A fibroadenoma usually presents as a firm rubbery nontender mass, often noted to be slowly enlarging over weeks to months. At the time of diagnosis, most fibroadenomas are 3 to 4 cm in size. Fibroadenomas are most often found in the upper outer quadrants of the breast, though they can occur elsewhere. They are not associated with nipple discharge. Overlying skin changes may be noted in a minority of cases, usually when the lesions are quite large. Lesions are typically solitary but may be multiple or bilateral in 10% to 25% of cases, a condition referred to as fibroadenomatosis. Some fibroadenomas regress spontaneously, while others remain stable in size or enlarge over time.

A juvenile or giant fibroadenoma is a fibroadenoma that is >5 cm in size. These masses are often noted to grow rapidly and sometimes reach sizes of >15 to 20 cm. The giant variant is less common than the regular form, but makes up a higher percentage of cases in early adolescence. Because giant fibroadenomas may compress or replace normal breast tissue, their potential for leading to a poor cosmetic outcome is greater.