Dermoscopic Clues for Sebaceous Carcinoma Arising in Nevus Sebaceous
Sebaceous carcinoma (SC) is a rare cutaneous malignant tumor that originates from the epithelium lining and arises from the sebaceous gland. It is particularly uncommon for SC to develop within a nevus sebaceous (NS), a congenital malformation of the skin that has a tendency to develop into benign or malignant neoplasms. This article presents a detailed case study of SC arising in NS, highlighting the dermoscopic findings that can aid in early diagnosis and treatment.
A 40-year-old Chinese woman presented with a yellowish, pruritic nodule on her forehead. The nodule had developed over a pre-existing, hairless yellowish plaque and was accompanied by pain for six months. Physical examination revealed a nodule measuring 0.5 cm by 0.5 cm, located over a yellowish plaque with associated erosion. Dermoscopic examination of the verrucous plaque showed aggregated yellow globules with non-arborizing crown vessels. The nodule itself exhibited yellowish inhomogeneous areas, polymorphous vessels, whitish superficial scaling, and an erythematous lesion.
Histopathological analysis of the nodule revealed pleomorphic lobules, vacuolated cells, foamy cytoplasm with scalloped nuclei, prominent nucleoli, and mitotic figures in the dermis. Immunohistochemistry results were positive for cytokeratin 7 and tumor protein P63, while epithelial membrane antigen was partly positive. Epithelial glycoprotein (BerEp4) and carcinoembryonic antigen were negative. Computed tomography of the head showed no evidence of metastases, confirming the diagnosis of SC arising in NS. The patient underwent wide local excision with a 1-cm margin, and there has been no evidence of recurrence during a 12-month follow-up period.
SC arising in NS is extremely rare, with only 25 cases reported in the literature. The estimated frequency of secondary neoplasms arising in NS is less than 0.1%. Other neoplasms that can arise in NS include basal cell carcinoma, trichoblastoma, squamous cell carcinoma, sweat gland carcinoma, syringocystadenoma papilliferum, and apocrine cystadenoma. Histopathology and immunohistochemistry are essential for accurate diagnosis, but early detection through dermoscopy can be highly beneficial.
Dermoscopic features of SC in NS include yellowish inhomogeneous areas, which correlate to the foamy cytoplasm seen in histopathology. Polymorphic vessels, such as hairpin, linear, and crown vessels, appear irregularly and are considered indicative of telangiectasia and malignancy. These features help differentiate SC from other lesions that may arise in NS, such as basal cell carcinoma, which shows asymmetrical large blue-gray ovoid nests, and trichoblastoma, which exhibits symmetrical large blue-gray ovoid nests. Syringocystadenoma papilliferum is characterized by exophytic papillary structures with ulceration and vessels, while apocrine hidrocystomas show symmetrical homogenous areas with arborizing telangiectasias.
The dermoscopic combination of SC arising from NS has not been previously reported in the literature. Given that SC arising in NS is a low-grade malignancy, early detection through dermoscopy can lead to successful control and treatment, preventing further metastasis. Timely recognition is crucial to avoid delayed diagnosis and potential complications.
In conclusion, dermoscopy is a powerful diagnostic tool that can aid in the early detection of SC arising in NS. The presence of yellowish inhomogeneous areas and polymorphic vessels are key dermoscopic clues that can help differentiate SC from other neoplasms that may arise in NS. Early diagnosis and treatment are essential for preventing recurrence and metastasis, highlighting the importance of dermoscopic examination in the management of these rare but potentially serious skin lesions.
doi.org/10.1097/CM9.0000000000000956
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