Figure 1

Microscopic and immunohistochemical examination of the resected HPN specimen. (A) A scanning magnification of HPN (H&E stains) showed well-circumscribed but uncapsulated dermal to superficial subcutaneous multi-lobulated nodular lesions in a plexiform manner, separated by a slightly dense and sclerotic collagenous stroma, and compressing the pre-existing sebaceous glands. Bar = 1 mm. (B) Its multi-lobulated parts (H&E stains) were composed of a proliferation of neoplastic cells, arranged in tiny round or whorled nests and embedded in a relatively abundant Alcian blue-positive myxoid stroma (inset). Bar = 200 μm. (C) High-power view demonstrated that most of these neoplastic cells had a small and oval to plump spindle shape, with vesicular nuclei, inconspicuous nucleoli, abundant pale eosinophilic cytoplasm, and indistinct cellular borders (H&E stains). Mitotic figures were very rarely encountered. Bar = 50 μm. (D) In immunohistochemistry, the tumor cells of HPN were specifically positive (insets) for MiTF (lt.) and Glut-1 (rt.). Bars = 20 μm.