Supplementary Material for: Novel Clinicopathologic Subungual Angiokeratoma Series Demonstrating Clinical Features Mimicking Nail Unit Melanoma

Introduction: Angiokeratomas are benign vascular tumors that typically present as a hyperkeratotic, red-brown to black papule on the lower extremities. Angiokeratomas in the subungual location are rare, with few reported cases in the literature. Case Presentation: We present three biopsy-proven cases of subungual angiokeratomas with novel clinical features: involvement of the nail bed, clinically mimicking nodular melanoma, and involving a broad age range, with the youngest patient reported at 25-years-old. Symptoms included tenderness and bleeding while the clinical presentations ranged from evenly to irregularly pigmented nodule(s). Histopathology revealed morphologic findings characteristic of angiokeratoma: multiple dilated vascular spaces within the superficial dermis and overlying epidermal hyperplasia. Conclusion: This case series expands the known clinical presentations of nail unit angiokeratomas and emphasizes the importance of including subungual angiokeratoma in the differential diagnosis of pigmented, nodular lesions of the nail unit.

引言：血管角皮瘤（Angiokeratomas）是一类良性血管性肿瘤，典型表现为下肢出现角化过度性、红褐至黑色的丘疹。甲下部位的血管角皮瘤较为罕见，文献中报道的病例寥寥无几。
病例报告：本文报告3例经活检证实的甲下血管角皮瘤病例，均具有新颖的临床特征：累及甲床、临床表现酷似结节性黑色素瘤（nodular melanoma），且患者年龄跨度较大，其中最年轻的患者仅25岁，为目前已有报道中年龄最小的病例。患者症状包括压痛与出血，临床表现为均匀或不均匀色素沉着性结节。组织病理学（histopathology）检查可见血管角皮瘤特征性形态学表现：真皮浅层可见多发扩张的血管腔隙，伴随表皮过度增生（epidermal hyperplasia）。
结论：本病例系列拓展了我们对甲单位（nail unit）血管角皮瘤已知临床表现的认知，并强调在甲单位色素沉着性结节性病变的鉴别诊断（differential diagnosis）中，需将甲下血管角皮瘤纳入鉴别范畴。