- The aim of this study was to identify risk factors for incomplete excision of squamous cell carcinomas (SCCs). A cross-sectional study of 369 patients who underwent a primary excision of SCCs was performed within an outpatient and a hospital plastic surgery department setting. Incomplete excision occurred in 25 of 369 primary excisions of SCC (6.8%). Location of the tumors on the forehead, temples, peri-auricular region, ears, cheeks, nose, lips or neck was significantly associated with incomplete excision of the tumors. In particular, high incomplete excision proportions were observed for tumors located on the ears (16.7%), neck (16.7%), temples (11.1%), nose (10.8%) or lips (7.1%). Incomplete excision of SCC was associated with the setting of the operation in the hospital as compared to ambulatory settings (p = 0.046) and was inversely associated with the specimen thickness (p = 0.002). There was no statistically significant association between incomplete excision of SCC and gender, age, clinical appearance of the lesion (suspected SCC vs other diagnoses), differentiation pattern, diameter of the tumor, length or width of the excised specimen, solar changes or ulceration. We recommend that in patients with SCCs located in the forehead, temples, periauricular region, ears, cheeks, nose, lips or neck surgeons should commence particular surgical measures to avoid inadequate excisions of the tumors. In particular, surgeons should use wider excisional margins in tumors located in the embryonic fusion planes (e.g. eyelids and naso-labial folds).