A 19 year old with complete androgen insensitivity syndrome and juvenile fibroadenoma of the breast.

We report a case of a 19-year-old female with complete androgen insensitivity syndrome (CAIS) who was diagnosed with a juvenile fibdroadenoma of the breast. The patient presented at age 18 with primary amenorrhea. She had been raised as a female and went through thelarche at age 13 and adrenarche at age 14. She had two sisters and three maternal aunts with androgen insensitivity syndrome. Physical exam revealed that the patient had no cervix, and a pelvic sonogram confirmed that the uterus was absent. Genetic analysis revealed a 46 XY karyotype. Bilateral intra-abdominal testes were noted on ultrasound and subsequently removed. She was placed on synthetic estrogen replacement therapy. Roughly 1 year following orchiectomy, the patient noticed an enlarging mass in her right breast. Physical exam revealed a roughly 5 cm mobile mass in the upper portion of the nipple-areolar complex. Ultrasound showed a solid mass consistent with a fibroadenoma. Because of the size of the lesion and the patient's hormonal make-up, a fine needle aspirate was obtained. Cytopathology showed large cohesive sheets of ductal epithelial cells, scattered histiocytes, numerous bare nuclei, fragments of fibrous tissue and metachromatic stroma. Some of the stroma was noted to be cellular. The tumor was subsequently excised. Microscopically, the lesion had epithelial and stromal hyperplasia consistent with a fibroadenoma. Phyllodes-like qualities of large size, increased stromal cellularity, and intracanalicular growth ("leaf-like projections") were noted; however, the pathologist found that the florid epithelial hyperplasia and the patient's young age were more compatible with a juvenile fibroadenoma. We describe what we believe to be the first report of a patient with CAIS and a fibroadenoma of the breast. The hormonal imbalance typically found in these patients, combined with the fact that most individuals with CAIS receive exogenous estrogen therapy, suggests that there may be a relatively high incidence of fibroadenoma in these patients.