Ki67 as a biologic marker of basal cell carcinoma: a retrospective study.

keY words: B asal cell carcinoma is the most common skin cancer in Caucasians worldwide [1-3]. It is associated with prolonged sun exposure, and in 85% of the cases occurs in the head and neck region [4,5]. This slow-growing tumor is locally destructive and has low metastatic potential [4-6]. Several parameters have been associated with increased aggressiveness of this lesion: tumor diameter, occurrence in the head, the aggressive-growth histological variants (infiltrative and morpheaform), depth of invasion, perineural invasion, and the expression of several biological markers including cyclin D1, p53, and Ki67 [6-11]. The Ki67 antigen, a high molecular weight non-histone nuclear protein, is generally accepted as the most reliable cell proliferative marker. Being expressed in all active cell cycle phases, the Ki67 antigen is superior by far to the mitotic count for the assessment of tumoral proliferative activity [9,12]. Ki67 labeling has been used as a diagnostic and prognostic tool in other tumors such as lymphomas, soft tissue sarcomas, and recently melanoma [12]. Healy et al. [13] examined the relationship between Ki67 proliferative index and the histopathological variants of BCC1, as well as the recurrence rate. The study showed that in cases of local recurrence, the primary tumors demonstrated significantly higher proliferative indices by Ki67, while there was no correlation seen between the BCC histological type and pattern of KI67 antigen expression [13]. The aim of the present study was to examine the relationship between the proliferative activity of BCC, as expressed by the Ki67 index, and its microscopic and clinical variables such as histological subtype, mitotic count, the presence of ulceration documented histologically, inflammation, tumor diameter measured macroscopically, and anatomic location. Patients and metHods The study group comprised 51 patients histopathologically diagnosed with BCC who were operated consecutively (28 by Mohs and the remainder by conventional excisions) during the year 2010. The corresponding paraffin-embedded blocks were retrieved from the archive of the Institute of Pathology at the Wolfson Medical Center, Holon, Israel. The selected samples BCC = basal cell carcinoma