Calcifying Basal Cell Carcinomas

Background. Dystrophic calcification refers to calcium deposition occurring in association with local tissue injury or abnormality. Little is known about dystrophic calcification occurring in malignant cutaneous neoplasms.
Objective. The purpose of this study was to determine the frequency and pattern of dystrophic calcification occurring in basal cell carcinomas and squamous cell carcinomas.
Methods. Consecutive cases (200) of basal cell carcinoma and squamous cell carcinoma were reviewed for evidence of dystrophic calcification. Histologic subtype, location of calcification, and tumor site were noted.
Results. Of 200 basal cell carcinomas, 41 (21%) showed evidence of dystrophic calcification, compared with 6 (3%) squamous cell carcinomas. Calcifying basal cell carcinomas were more likely to have a more aggressive histologic subtype and to be located on the trunk.
Conclusion. Skin calcium binding protein may be responsible for the calcium deposition and account for the discrepancy seen between the frequency of calcification occurring in basal cell carcinomas and squamous cell carcinomas. As with other tumors with follicular differentiation, calcium deposits were located in keratin-filled cysts. This pattern of dystrophic calcification may be a marker of follicular differentiation.