PMC6147009_01
Macroscopic and microscopic appearances of the nipple neurofibroma. (a) Gross appearance of the largest lesion showing a pedunculated polypoid mass. (b) Overall H&E view showing a polypoid lesion covered by unremarkable squamous epithelium. (c) Low power H&E section showing bland spindle shaped cells interspersed with smooth muscle bundles of the nipple. (d) High power H&E section showing moderately cellular bland spindle cells extending close to a large mammary duct. There is no cytological atypia or mitoses. The adjacent mammary duct is benign and lined by inner luminal and outer myoepithelial cells. The lesional spindle cells show immunoreactivity for desmin (e), neurofilament (f), and S100 (g and h).
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On clinical examination, bilateral, pedunculated, polypoid, and fleshy lesions were noted on both nipple-areolar complexes (Figure 1(a)). Microscopically, both specimens showed dermal proliferations of bland spindle-shaped cells with elongated wavy dark nuclei (Figures 1(b)-1(d)). Spindle cell proliferation extended close to a mammary duct (Figure 1(d)); however, it must be noted that these lesions did not arise from the breast parenchyma but included smooth muscle fibres of nipple and were in close proximity to mammary ducts. Immunohistochemistry (IHC) supported the neural differentiation of the spindle cells with immunopositivity for S100 and neurofilament (Figures 1(f)-1(h)). Desmin (Figure 1(e)) and smooth muscle myosin on IHC highlights the florid component of associated smooth muscle.