Endoscopic Submucosal Dissection of Seborrheic Keratosis-Like Lesion of the Esophagus: A New Entity?

Seborrheic keratosis, one of the most common lesions of the epidermis, is rarely seen on mucosal surfaces. We report a case of a distinctive epithelial neoplasm of the esophagus showing close resemblance to seborrheic keratosis that was resected with endoscopic submucosal dissection. A 65-year-old patient's previous esophageal biopsy showed suspicious low grade dysplasia and the patient was referred for endoscopic submucosal dissection of a flat lesion in the mid-esophagus. Macroscopic examination revealed a well circumscribed, pigmented and elevated lesion with a diameter of 20 mm. Microscopically, the lesion was well circumscribed, with plaque-like elevation, and showed hyperkeratosis, acanthosis, and papillomatosis. Broad coalescing solid sheets and interconnecting trabeculae of basaloid cells were the consistent feature throughout the lesion. Squamous eddies and occasional central keratinization were present. Mitotic activity and koilocytes were not identified. Immunohistochemically, the lesion showed diffuse nuclear positivity with p63 and negativity with p16. Ki-67 index was confined to the basal cell layer. With the help of histopathologic and immunohistochemical findings, we diagnosed this morphologically benign case as "seborrheic keratosis-like lesion of the esophagus". It should be kept in mind that seborrheic keratosis-like lesions might be rarely seen on mucosal surfaces such as the esophagus. Endoscopic submucosal dissection is a new, curative, and safe endoscopic resection technique in en-bloc resection of superficial esophageal lesions. To our knowledge, this is the first case of the aforementioned lesion in the esophagus being resected with endoscopic submucosal dissection.