DS06: Contending with COVID-19 in a Mohs micrographic surgery service

D. Jackson,¹ E. Edmiston,² S. Butt,¹ M. O’Reilly,¹ A. Khalid¹ and C. Fleming¹

¹NHS Tayside and ²University of Dundee, Dundee, UK

The COVID-19 pandemic has placed significant pressure on healthcare services worldwide. We sought to better understand its impact on our Mohs micrographic surgery (MMS) by comparing outcomes from 2019 and 2020 for basal cell carcinoma (BCC) Mohs excisions. Additionally, we outline the systems and changes to patient pathways we undertook to minimize delay to treatment while running a reduced service, and discuss the benefits and consequences of such changes. We retrospectively reviewed the Mohs dataset and electronic records of patients referred for MMS between June and September in 2019 and 2020. Owing to the COVID-19 pandemic in the spring of 2020, MMS was stopped, with select cases retriaged for standard excision and a reduced MMS service recommenced in June 2020. Additionally, we analysed the outcomes of histological clearance in these 14 patients (16 lesions). Seventy-nine MMS procedures were performed between June and September 2019 vs. 74 over the same period in 2020. The mean waiting time for surgery increased from 164 days to 203. The average number of Mohs stages increased from 1·44 to 1·54. In 2019, 60% of cases were histologically clear after stage 1, 38% after stage 2, 1% after stage 3 and 1% after stage 4. In 2020, 55% of cases were histologically clear after stage 1, 37% after stage 2, 7% after stage 3 and 1% after stage 4. There was an increase in the average postoperative defect from 941 mm² in 2019 to 1043 mm² in 2020. While rates of BCC growth are generally considered slow, rapid growth in periocular lesions has been noted (Tan E, Lin FP, Sheck LH et al. Growth of periocular basal cell carcinomas. Br J Dermatol 2015; 172: 1002–7). There was a reduction in the use of secondary intention healing, falling from 28% in 2019 to 14% in 2020. Of the 16 lesions that did not receive MMS, 12 specimens achieved complete clearance on conventional histology, one a narrow clearance and three were incompletely excised. The unusual circumstances of the COVID-19 pandemic have provided insights into managing skin cancer without access to MMS. Our data suggest that prolonged halting of MMS for BCC does affect outcomes, with a trend towards more Mohs stages, a larger postoperative defect and more complex reconstruction. Retriage to standard excision demonstrated mixed clearance results on conventional histology. While prioritizing urgent care is essential in extremis, preserving MMS where possible may reduce the overall burden of disease in the long term. For patients with high-risk features or recurrent BCC, MMS remains the gold standard.