Expression of calretinin in odontogenic keratocysts and basal cell carcinomas: A study of sporadic and Gorlin-Goltz syndrome-related cases

Gorlin-Goltz syndrome (GGS), is an autosomal dominant inherited disorder related to germline mutation of PTCH1 gene, characterised by the presence of multiple developmental anomalies and tumours, mainly basal cell carcinomas (BCC) and odontogenic keratocysts (OKC). We analysed and compared the expression of calretinin in 16 sporadic OKCs, from 15 patients, and 12 syndromic OKCs from 11 patients; in 19 BCC's and 2 cutaneous keratocysts (CKC) belonging to 4 GGS patients, 15 sporadic BCCs and 3 steatocystomas (SC). Calretinin was negative in 10 of 12 syndromic OKCs, focally positive (< 5% of cells) in 2; six sporadic OKCs were negative, 6 focally and 4 diffusely positive (p =.02, cases focally and diffusely positive vs. cases negative). All BCCs of 3 GGS patients were negative, the fourth patient presented two BCCs negative and 5 focally or diffusely positive; 7 sporadic BCCs were negative and 8 focally positive (p = NS). Two CKCs resulted negative in one GGS patient; 2 sporadic SCs were positive, and a third was negative. PTCH1 mutations produce an altered PTCH protein and an aberrant activation of Sonic hedgehog (SHH) pathway, leading to tumoral proliferation. It has been demonstrated that treatment of human foetal radial glia cells with SHH reduces, whereas the blockage of SHH increases calretinin expression. We found a lower expression of calretinin in syndromic OKCs compared to sporadic cases. Although calretinin's value in differential diagnosis between sporadic and syndromic tumours appears not crucial, our results shed light on the possible link between SHH dysfunction and calretinin expression in GGS-related tumours.