What to Expect When Treating SCC In Situ with Mohs Surgery
While squamous cell carcinoma in situ (SCCIS) is typically considered a low-risk skin cancer, treatment decisions, especially around surgical approach and location, still matter. A recent JDD study offers valuable insights into how SCCIS behaves under the scalpel during Mohs micrographic surgery (MMS).
In “Squamous Cell Carcinoma In Situ on High-Risk Sites and With Larger Sizes Require More Stages for Clearance With Mohs Surgery” , the authors prospectively tracked 485 SCCIS cases over three years. Most tumors were small (mean size just under 1 cm) and primary. But key findings emerged: tumors in high-risk areas (Area H, like the face) required significantly more Mohs stages to clear compared to lower-risk areas (Areas M and L). Notably, curettage before surgery didn’t reduce the number of stages needed.
These results suggest that even in situ tumors can show subclinical spread, particularly in cosmetically or functionally sensitive sites. This reinforces the utility of MMS for SCCIS—especially in high-risk zones—where margin control is paramount.
J Drugs Dermatol. 2025;24(5):494–497)
