Pigmented Bowen disease: A challenging dermoscopic feature due to a traumatic disfigurement

Dear Editor, The characteristic dermoscopic features of Bowen disease have been reported. However, variations of the dermoscopic features of Bowen disease have not been fully elucidated to date. The dermoscopic features at the foot should be cautiously evaluated due to potential modifications due to mechanical stimuli such as trauma and irritation. Here, we present the dermoscopic features of Bowen disease at the foot with traumatic disfigurement. A 72-year-old man presented with a nodule with erosion on his foot. The patient had bruised the lateral malleolus of his foot 2 months before, and a nodule had developed at the bruise. Physical examination revealed an elevated 6 mm 9 6 mm dusky-red nodule with an erosion in the center on his lateral malleolus (Fig. 1a). Dermoscopy revealed glomerular vessels arranged annularly on a light-brown structureless area (Fig. 1b), and glomerular vessels were clearly seen at the edge of the erosion. At the base of the erosion, a pink homogenous area with slight whitish areas was seen (Fig. 1c). Brown structureless areas with a whitish veil were found at the periphery (Fig. 1d). Histopathological examination at the erosion of the tumor revealed the lack of a cornified layer (Fig. 1e). Elongations of rete ridges of atypical cells were prominent. Blood vessels ascended between the elongated tumor nests (Fig. 1f), and numerous mitoses were found (Fig. 1g). Histopathological examination at the periphery of the tumor revealed acanthosis with atypical cells (Fig. 1h) and melanocytes were scattered in the epidermis (Fig. 1i). Immunohistochemistry showed positive reactions for p63, p40, cytokeratin (CK)17 and AE1/3, and negative reactions for S100, adipophilin, p16 and CK1. Immunohistochemistry for a-smooth muscle actin and CD34 showed that blood vessels ascended and were partially dilated in the ascending dermis between the elongated tumor nests (Fig. 1j). Immunohistochemistry for Melan-A showed scattered melanocytes in the whole epidermis (Fig. 1k). Fontana–Masson staining showed melanin deposition both at the basal layer and in the spinous layer (Fig. 1l). From those clinical and histopathological findings, the diagnosis of pigmented Bowen disease was made. An additional resection of the tumor with a 5-mm surgical margin was performed, and there has been no relapse in the 5 months since then. The dermoscopic features of pigmented Bowen disease are characterized by both vascular structures and epidermal structures. However, those dermoscopic features may manifest atypical findings depending on several factors such as the location and mechanical stimuli. Mechanical stimuli, which results in traumatic disfigurement, may modify dermoscopic features as an enhancement of vascular structures in basal cell carcinomas (BCC). As a differential diagnosis, pyogenic granuloma, eccrine poroma, BCC, nodular melanoma and Bowen