A Retrospective Analysis of Complication Rates in Mohs Micrographic Surgery Patients With Clinically Large Tumors and Tumors With Aggressive Subclinical Extension

May 2018 | Volume 17 | Issue 5 | Original Article | 511 | Copyright © May 2018

Natasha Cowan BS, Alina Goldenberg MD MAS, Pallavi Basu BA, Robert Eilers MD, Jennifer Hau MD, and Shang I Brian Jiang MD

University of California San Diego, San Diego, CA

Background: Clinically large cutaneous tumors and those with aggressive subclinical extension (ASE) often require wider margins and increased operative time during Mohs micrographic surgery (MMS). Our goal is to improve dermatologic surgeons’ counseling information on complication risks for aggressive tumors. Objective: To examine the incidence of postoperative complications in MMS patients, with a focus on differences between aggressive and non-aggressive tumors. Methods and Materials: We performed a retrospective cross-sectional chart review of 4151 MMS cases at the University of California, San Diego. A postoperative complication was defined as an adverse event directly related to MMS reported within 6 weeks of the procedure. Results: Clinically, large tumors had 50 times the odds of postoperative complication as compared to all other tumors (P less than 0.001). ASE was not found to be significantly associated with higher rates of postoperative complications when controlled for other factors. Conclusion: Clinically, large tumors may be at higher risk for complications following MMS due to their increased size and need for repair with methods other than linear closures. Tumors with ASE were not found to be at higher risk for postoperative complications. J Drugs Dermatol. 2018;17(5):511-515.


The complications associated with dermatologic surgery for patients with non-aggressive tumors have been previously reported in the literature. While postoperative hemorrhage, necrosis, and infection have been reported to occur with Mohs micrographic surgery (MMS), these complications occur at rates as low as 0.72%.1 Therefore, the risk of leaving the tumor untreated typically outweighs the risks of these postoperative complications.2,3 With this information, dermatologic surgeons can appropriately counsel patients on potential post-operative complications associated with dermatologic surgery for patients with non-aggressive tumors.2,4Non-melanoma skin cancers that are clinically large (defined as >2 cm in diameter) and those with aggressive subclinical extension (ASE, defined as ≥3 stages of MMS and ≥1 cm final surgical margins) often require wider surgical excision margins during dermatologic surgery to obtain clear margins, and may therefore result in larger postoperative defects. Furthermore, the increased number of MMS stages associated with treatment of lesions with ASE entails longer surgical times.5 Although it is recognized that tumors with ASE and clinically large tumors may carry a risk of perioperative and postoperative complications, specific studies investigating the incidence of postoperative complications associated with lesions with ASE and clinically large tumors following dermatologic surgery are lacking. Dermatologic surgeons require a comprehensive understanding of the postoperative complications associated with the treatment of skin cancers with aggressive subclinical extension (ASE) and clinically large tumors for appropriate surgical planning and patient counseling. Our retrospective study examines the incidence and nature of postoperative complications in patients with tumors with ASE and clinically large tumors following dermatologic surgery in comparison to non-aggressive tumors to provide better understanding and improve the surgical management of these more challenging lesions. 


Our retrospective review was performed at the Dermatologic and Mohs Surgery Center of University of California, San Diego (UCSD). This study was approved via expedited review by the UCSD Institutional Review Board. All MMS procedures performed on SCC and BCC presenting between July 1, 2011 and June 30, 2015 were assessed. Data was gathered via electronic medical record review. Patient characteristics including age at surgery and gender were collected. Clinical characteristics included location of tumor,