We all use biopsy to confirm the clinical diagnosis of basal cell carcinoma (BCC), to determine the sub-type of BCC, and hence to plan the formal treatment – this is usually by excision with appropriate margins, but of course we also consider other destructive methods or topical treatments.
Colleagues will be aware of the technology that is reflectance confocal microscopy (RCM). This is special imaging of the sub-structure of the skin, typically available in specialist centres, and can be used to identify BCC sub type, and to map margins.
Woliner-van der Weg W et al published this paper in the British Journal of Dermatology: Biopsy outperforms reflectance confocal microscopy in diagnosing and subtyping basal cell carcinoma: results and experiences from a randomized controlled multicentre trial.
The authors showed that while both RCM and punch biopsy methods had high rates of sensitivity (99%), the accuracy of RCM was lower for BCC diagnosis (specificity, 59.1% vs 100%) and had a significantly worse accuracy for the subtyping of aggressive subtypes (specificity, 33.3% vs 77.3%).
The authors concluded that the routine clinical implementation of RCM for the diagnosis of BCC is not supported.
So, for us, in primary care practice, we can continue to use the reliable punch biopsy tool for suspected BCC. However, it is useful to be aware of RCM, as it might be useful for mapping large lesions and assessing suspected BCCs in delicate areas such as eyelids. Furthermore, RCM has already been shown to be useful for mapping lentigo maligna.
