What are the indications for Mohs micrographic surgery in the treatment of cutaneous squamous cell carcinoma?

Indications for Mohs micrographic surgery (MMS) in cutaneous squamous cell carcinoma (cSCC) primarily include tumours located in anatomically critical or cosmetically sensitive areas, such as the head and neck region, where tissue preservation is paramount and recurrence risk is high NICE NG14. MMS is particularly indicated for high-risk cSCC characterized by features such as poorly defined clinical margins, recurrent tumours, aggressive histological subtypes (e.g., poorly differentiated or desmoplastic), perineural invasion, and tumours arising in sites with a higher risk of local recurrence or metastasis, including the ears, lips, and genitalia NICE NG14 Bittner et al. 2021. Additionally, MMS is preferred for tumours in immunosuppressed patients or those with prior radiation therapy to the site, where standard excision may have higher failure rates NICE NG14 Zürcher et al. 2024.

Furthermore, MMS offers the advantage of complete margin assessment during surgery, which is critical for ensuring clear margins in high-risk cSCC and reducing recurrence rates compared to conventional excision NICE NG14 Nouri & Rivas 2004. The UK guidelines emphasize MMS for cSCCs that are large (>2 cm), deeply invasive, or located in areas where tissue conservation is essential for functional or aesthetic reasons NICE NG14. Recent literature supports these indications and highlights the role of MMS in managing complex or recurrent cSCCs, reinforcing its use as a tissue-sparing technique with superior margin control and lower recurrence [Bittner et al., 2021; Zürcher et al., 2024].