Background Giant congenital melanocytic nevus (GCMN) is a rare disease, for which complete surgical resection is recommended. However, the size of the lesions presents problems for the management of the condition. The most popular approach is to use a tissue expander; however, single-stage expansion in reconstructive surgery for GCMN cannot always address the entire defect. Few reports have compared tissue expansion techniques. The present study compared single and serial expansion to analyze the risk factors for complications and the surgical outcomes of the two techniques.Methods We retrospectively reviewed the medical charts of patients who underwent tissue expander reconstruction between March 2011 and July 2019. Serial expansion was indicated in cases of anatomically obvious defects after the first expansion, limited skin expansion with two more expander insertions, or capsular contracture after removal of the first expander.Results Fifty-five patients (88 cases) were analyzed, of whom 31 underwent serial expansion. The number of expanders inserted was higher in the serial-expansion group (P<0.001). The back and lower extremities were the most common locations for single and serial expansion, respectively (P=0.043). Multivariate analysis showed that sex (odds ratio [OR], 0.257; P=0.015), expander size (OR, 1.016; P=0.015), and inflation volume (OR, 0.987; P=0.015) were risk factors for complications.Conclusions Serial expansion is a good option for GCMN management. We demonstrated that large-sized expanders and large inflation volumes can lead to complications, and therefore require risk-reducing strategies. Nonetheless, serial expansion with proper management is appropriate for certain patients and can provide aesthetically satisfactory outcomes.

Background: Pressure ulcers are a common and challenging problem affecting bed-ridden patients. Flap operations are considered a surgical option for treating pressure sores despite their high rate of complications and recurrence. Hypothesizing that certain factors would affect postoperative outcomes for pressure sore patients, we analyzed the factors and outcomes.<br/>Methods: We collected cases retrospectively from January 2010 to January 2018. The subjects were 95 patients who had undergone flap operation in our institution. Patient demographics, wound characteristics, and outcomes including relapses, flap complications, reoperation, and newly developed sores were analyzed. Logistic regression analysis was used to identify the association between variables and surgical outcomes.<br/>Results: Patients who had larger area of defects after debridement had more flap complications (P=0.01) and were more likely to undergo reoperation (P=0.03). Smokers (P=0.04) and patients whose wound cultures were positive (P=0.04) had more flap complications. Patients who had paralysis were more likely to require reoperation (P=0.02) and to develop new sores (P=0.02).<br/>Conclusion: We identified factors affecting postoperative outcomes after flap operation to cover pressure sores. As a more comprehensive preoperative risk assessment on flap reconstruction for pressure sores can improve outcomes, these indicators should be carefully considered when determining surgical options.