An unusual case of a large fibroepithelial stromal polyp presenting as a nipple mass

Abstract

Background: Fibroepithelial stromal polyps (FESP) are benign lesions that typically occur in the genital area and are known to represent a diagnostic challenge for pathologists. Not only do they have a spectrum of morphological changes that ranges from bland morphology to rather atypical appearances, but they also share morphological features with a number of benign and malignant lesions.This is a report of a rare presentation of a FESP of the breast.

Case presentation: We describe an unusual case of a large polypoid mass arising from the nipple and connected to it by a long pedicle in a female of 45. The lesion comprised spindle and stellate shaped cells with bizarre stromal giant cells. The morphological and immunohistochemical diagnostic features are provided together with a discussion of possible mimics.

Conclusion: FESPs may occur in the female breast. It is important to differentiate the lesion from other benign and malignant spindle cell lesions particularly metaplastic carcinoma.

Figure 1

Clinical presentation of the lesion. (A-D): a polypoid mass originating from the nipple, to which it is connected by a long pedicle. Both breasts are otherwise unremarkable.

Figure 2

Histological appearances of the lesion. A. Low power view of the lesion illustrating the polypoid appearance (x20). B and C: The lesion is rather hypocellular. The stroma comprised spindle and stellate shaped cells B(x100) and C(x400). D- CD34 immunohistochemistry showing a large number of variably-sized blood vessels within the stroma (x200). E- Stromal cells are positive for factor X111a (x400). F- The cells are negative for EMA. Note positivity of the overlying epithelium (x200). G- Caldesmon showing positive expression in the muscle coat of the lesional vessels. Stromal cells are not stained (x200). H- Stromal cells are negative for oestrogen receptor (x400).