Basal cell carcinomas without histological confirmation and their treatment: an audit in four European regions.

BACKGROUND: Limited data are available on how often basal cell carcinomas (BCCs) are clinically diagnosed without histological confirmation and how they are treated. OBJECTIVES: Within the framework of the EPIDERM project, an audit was conducted in four European countries to study the occurrence of clinically diagnosed BCCs without histological confirmation and to investigate how these are treated. METHODS: In the Netherlands, Scotland, Finland and Malta studies were performed within different timeframes. Patients with one or more BCC(s) were selected and the number of clinically diagnosed BCCs without histological confirmation and their treatment was investigated by (manually) reviewing the (electronic) patient records and checking the (hospital) pathology databases to find evidence of histological confirmation. RESULTS: In the Netherlands, 1089 patients with a first histologically confirmed BCC developed 1974 BCCs of which 1833 (92·9%) were histologically confirmed and 141 (7·1%) were not. A 4-month retrospective study conducted in Scotland selected 294 patients with 344 BCCs; 306 (89·0%) were histologically confirmed and 38 (11·0%) were not. A 3-month prospective study performed at the same centre in Scotland identified 44 patients who developed 58 BCCs; 44 (75·9%) of these were histologically confirmed and 14 (24·1%) were not. In Finland, there were 701 patients who developed 977 BCCs, of which 807 (82·6%) were histologically and 170 (17·4%) nonhistologically confirmed. In Malta, there were 420 patients with 477 BCCs. Only three (0·7%) of them were clinically diagnosed without histological confirmation. In the Netherlands and Finland, clinically diagnosed BCCs without histological confirmation were most often treated with cryotherapy, whereas in Scotland 5% imiquimod cream was the preferred treatment modality. CONCLUSIONS: Although the frequency of clinically diagnosed BCCs without histological confirmation differed between the four European regions (range 0·7-24·1%), this confirms that the burden of BCC in Europe is underestimated when based on data from pathology and/or cancer registries.