Challenging Diagnosis of Nodular Fasciitis of the Breast in an Adolescent—A Case Report—

Abstract

The patient was an 18-year-old woman who had experienced recurrent, self-resolving subcutaneous hemorrhages in her right breast over the past 6 months. Three months prior, she consulted her physician after noticing a mass in her right breast. Ultrasonography revealed an 11-mm mass in the right C region. Despite performing a vacuum-assisted biopsy, the mass remained difficult to characterize, prompting referral to our department. On examination, a 10-mm firm elastic mass was palpated in the right C area. Mammography revealed architectural distortion in the right U area, whereas ultrasonography revealed a 12-mm irregular hypoechoic mass with irregular borders and architectural distortion in the same area. Magnetic resonance imaging revealed a 16-mm contrast-enhancing lesion in the corresponding region. The previously performed needle biopsy specimen revealed interlacing spindle-shaped cells, and immunostaining was positive for α-SMA, suggesting a smooth muscle tumor. Considering the high cell density and Ki-67 index of 10%, the possibility of a borderline malignant lesion could not be ruled out;therefore, the patient underwent a right mastectomy. Postoperative histopathological evaluation revealed proliferation of interlacing spindle-shaped cells with mild-to-moderate nuclear enlargement, positive for α-SMA, and negative for CD34 on immunostaining, suggesting nodular fasciitis. Here, we present this case along with a review of the literature.