Clinicopathological factors and dermoscopic features associated with incomplete excision of malignant cutaneous adnexal tumors

Introduction: Malignant cutaneous adnexal tumours (MATS) are rare, heterogeneous tumours of variable malignancy that originate from hair follicles, sebaceous glands, eccrine, or apocrine sweat glands. Surgical excision with clear margins is the gold standard for treating MATS. Incomplete excision increases the risk of local recurrence, subclinical tumour progression, and metastasis. Aim: The aim of our study was to determine the clinicopathological risk factors and dermatoscopic features associated with incomplete excision of MATS. Material and methods: We conducted a single-centre retrospective study by evaluating patients’ data diagnosed with MATS who underwent primary surgical excision during January 2020 - December 2022. We assessed the clinical, dermatoscopic, and histopathological features of the tumours, and the demographic characteristics of the patients. Pertaining to the margin of the surgical resection we divided the cases into two groups: we considered the surgical margins positive if there were tumour infiltrations, or located tumour cells less than 1 mm from the resection margins; otherwise, we considered the surgical margins negative. We used Microsoft Excel and GraphPad Prism 9.0 to perform statistical analyses. Results: During the three-year period, a total of 17 patients who underwent surgical resection of MATS were included in the study. Incomplete excision occurred in 9 cases (52.9%). All cases included in the study were located in the head and neck area. The periocular region was the most common location (33.3%), followed by the nasal and hemifacial areas in equal proportions (22.2%). During dermatoscopic examination, tumours with incomplete resection margins were mainly characterized by uniform or clustered polymorphous vessel morphologies. We found a significant correlation between incomplete resection and microcystic adnexal type carcinoma (p=0.025). We did not find any statistically significant correlation between incomplete excision and gender, age, tumour size, thickness/invasion, and localization. Conclusion: The therapy of choice for locally aggressive MATS is complete tumour control with resection, especially in the high-risk “H” zone of the head and neck area. If this is not feasible, excision with the extension of the safety margins is recommended.