Abstract
There are some fibroadenomas growing rapidly in juvenile individuals and they are called juvenile fibroadenomas. Twenty cases of the disease affecting juveniles of 15 and under have been reported in Japan. A 14-year-old girl who had her first menstruation four months before visited our hospital. She had been aware of a rapidly growing mass in her left breast since one month after her menarche. A 10-cm elastic soft mass was palpable in her left breast. Contrast-enhanced magnetic resonance imaging scan showed a 12-cm mass with gradually increased enhancement in the left ECD area. Core-needle biopsy resulted in the diagnosis of fibroadenoma. Because the large tumor continued to increase in size, extirpation of the tumor with an incision on inframammary fold was performed. Histopathologically, the tumor was diagnosed as juvenile fibroadenoma. Immunohistochemically, estrogen receptor was positive and the ratio of Ki-67-positive cells was approximately 20%.
It is speculated that a rapid growth of fibroadenoma in the present case may be attributable to estrogen stimulation, because the tumor started to increase in size one month after her menarche.
