A 34-year-old woman comes to the clinic due to a mass in her right breast. The patient noticed the mass last week while in the shower. She has no chronic medical conditions and takes no daily medications. A 2-cm nodule is noted on examination of the right breast, and the patient is referred for biopsy. Histologic evaluation of the tissue specimen is shown in the image below: Which of the following is the most likely diagnosis?

Question

A 34-year-old woman comes to the clinic due to a mass in her right breast.  The patient noticed the mass last week while in the shower.  She has no chronic medical conditions and takes no daily medications.  A 2-cm nodule is noted on examination of the right breast, and the patient is referred for biopsy.  Histologic evaluation of the tissue specimen is shown in the image below:  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_391f_0c67_9249_43e8d7cb30dd_MD0001_00 This patient has a fibroadenoma, the most common, benign breast tumor diagnosed on breast biopsy. Fibroadenomas typically arise in women age 15-35 and are usually spherical masses measuring 1-10 cm. They are classically firm, nontender, well circumscribed, and mobile. Fibroadenomas are estrogen-sensitive. They can increase in size with pregnancy, lactation, or estrogen therapy. Fibroadenomas usually regress after menopause. Therefore, in younger women, fibroadenomas are usually discovered as a palpable mass; in older patients, they are more often found incidentally on mammography. Fibroadenomas are fibroepithelial tumors composed of a benign-appearing cellular or myxoid stroma that encircles epithelium-lined glands and cystic spaces (ie, contains both stromal and ductal elements). The lesions typically have a well-defined border due to a fibrous capsule, and the proliferating stroma may compress and distort the glandular components. As women age, the epithelium atrophies and the stroma becomes more hyalinized. (Choice A) Ductal carcinoma in situ (DCIS) is a breast lesion characterized by neoplastic epithelial cell proliferation (eg, atypical epithelial cells with prominent nucleoli, mitotic figures) contained by the surrounding ductal basement membrane. (Choice C) Mammary duct ectasia is characterized by ductal dilation, inspissated (ie, thickened) breast secretions, and chronic granulomatous inflammation in the periductal and interstitial areas. (Choice D) Medullary carcinoma is characterized by solid sheets of vesicular, pleomorphic, mitotically active cells with a significant lymphoplasmacytic infiltrate around and within the tumor and a pushing, noninfiltrating border. (Choice E) Paget disease of the nipple is a rare form of breast cancer in which malignant cells spread from superficial DCIS into nipple skin without crossing the basement membrane. Physical examination shows unilateral erythema and scale crust around the nipple. (Choice F) Sclerosing adenosis is characterized by central acinar proliferation and compression with surrounding fibrotic tissue and peripheral ductal dilation. Sclerosing adenosis is a common finding in women with fibrocystic breast changes. Educational objective: Fibroadenomas are the most common benign tumor of the breast. They are characterized histologically by a myxoid stroma that encircles and sometimes compresses epithelium-lined glandular and cystic spaces. __________ References: Fibroepithelial tumors of the breast: pathologic and immunohistochemical features and molecular mechanisms. (http://www.ncbi.nlm.nih.gov/pubmed/24377809)

A 34-Year-Old Woman Comes to the Clinic Due to a Mass