Usefulness of Dermoscopy in the Differential Diagnosis of Ruptured and Unruptured Epidermal Cysts

Background: An epidermal cyst is a common keratin-filled epithelial-lined cyst. The treatment of choice for epidermal cysts is surgical excision. If the cyst becomes ruptured, incision and drainage with oral antibiotic therapy or intralesional steroid injection are required. Objective: To analyze the dermoscopic features that can differentiate between ruptured and unruptured epidermal cysts. Methods: The clinical and dermoscopic features of the pathologically confirmed epidermal cysts of two subgroups of 38 patients, 20 with unruptured cysts and 18 with ruptured cysts, were reviewed. Results: With regard to the dermoscopic features, an ivory-white background color and punctum were commonly found in both groups (p>0.05). The unruptured-cyst group showed higher frequencies of pore sign (p<0.05), blue-white veil (p>0.05), no vascular structure, and arborizing telangiectasia (p<0.05), but the ruptured-cyst group usually had red lacunae (p>0.05) and peripheral linear branched vessels (with an erythematous rim) (p<0.05). Conclusion: Dermoscopy is helpful in differentiating between ruptured and unruptured epidermal cysts.