Clinical triage of cutaneous squamous cell carcinoma and basal cell carcinoma to avoid treatment delay: value of an electronic booking system

Summary Background Provisional clinical diagnosis is the first step in planning skin surgery. Different clinical priorities are given to basal cell carcinoma ( BCC ), squamous cell carcinoma ( SCC ) and malignant melanoma ( MM ). Discriminating between SCC and BCC can be difficult. The rate of misdiagnosis of SCC as BCC is reported as 5.7–87.6%, and can cause treatment delay. We have developed a web‐based surgery booking system that requires clinical commitment to a putative differential diagnosis category, rather than a single diagnosis, at the time of consultation. This includes a crucial overlap category of ‘ SCC or SCC / BCC ’. Aim To assess whether our system helped avoid treatment delay to patients with SCC , and to measure the number needed to treat ( NNT ). Methods This was a retrospective analysis from A pril 2012 to A ugust 2013, comprising all patients undergoing booked excisional surgery in our unit. The clinical triaging category was compared with the histological diagnosis. Sensitivity, specificity, positive predictive value, negative predictive value ( NPV ), NNT and mean Breslow thickness were calculated. Results In total, 1455 lesions were excised, identifying 789 (54.2%) invasive malignancies (86 MM , 115 SCC , 583 BCC , 5 other), 100 in situ lesions and 150 dysplastic lesions. The majority (83.2%) of malignancies were designated into the correct malignant category. Misdiagnosis of SCC as BCC was 5.2%. Sensitivity and NPV for SCC were 94.8% and 99.4%, respectively. NNT was 1.26, 4.12 and 3.19 for BCC , SCC and MM respectively, and 1.73 for all malignancies. Mean invasive Breslow thickness was 1.29 mm [0.78 mm including melanoma in situ ( MMIS )], and the MM to MMIS was 1.6. Conclusion An overlap triage category of ‘ SCC or SCC / BCC ’ helps to prevent delay in the treatment for patients with SCC .