TA is a rare entity and sometimes occurs with SCAP. SCAP was previously reported to be often associated with pre-existing nevus sebaceous [7], and morphologic features of nevus sebaceous seldom existed in SCAP with TA [1]. No nevus sebaceous is seen in our case. Controversy about the relationship of TA and SCAP still exists. TA was considered as a minor variant of SCAP by some scholars [8], but others have suggested that TA is a distinct clinical entity [7]. In Kazakov's recently published study, 67 cases of TA, SCAP, and their lookalikes were assessed by four dermatopathologists. Only 29 cases got concurrent agreement and interobserver variation existed in other 38 cases.
TA or SCAP was reported to have certain relationship with human papillomavirus infection [9] and a human papillomavirus induced non-neoplastic process leading to TA or SCAP was also speculated by some authors [1]. Warty surface or koilocytotic feature is not seen in our case.
Immunohistochemical study may be useful in puzzling cases. S-100 protein was reported to be detected in the peripheral myoepithelial cells in the TA and failed to be present in the SCAP [7, 10], which was consistent with the immunohistochemical results of our presented case.
Treatment of LTA with SCAP includes careful preoperative evaluation and surgical resection with safe margin. Computed tomography is useful in evaluating the tumor and surrounding tissue.