Clinicopathological factors associated with trichilemmal cysts.

Trichilemmal cysts (pilar cysts) are common adnexal tumors that mostly affect the scalp. They are usually benign, but can sometimes be malignant. Despite being common, there is limited data on what factors influence lesion size, multiplicity and risk of infection. The present retrospective observational study evaluated 27 patients who underwent excision of trichilemmal or related cystic tumous between January 2020 and June 2025 at a tertiary plastic surgery centre. The clinical nkvariables encompassed age, sex, diabetes mellitus (DM), hypertension (HT), tobacco use, Fitzpatrick skin type, and, in female patients, headscarf use and Ludwig hair loss score. Tumou size, multiplicity and infection were assessed. The mean age was 44.4 ± 15.6 years (range 17-82), with 59 % (16/27) females. The median tumor size was recorded as 21 mm [8,30] and the median duration from first awareness to excision was 18 months [8,27]. Infection was identified histopathologically in a minority of cases and showed trends toward association with DM and HT. Patients with multiple lesions were older (median 54 vs. 38.5 years, p=0.009) and had larger tumors (median 30 vs. 9 mm, p<0.0001). Linear regression revealed that age and DM independently predicted larger lesions, while HT was negatively associated. No correlations were identified with tobacco use, Fitzpatrick skin type, or headscarf status. These results emphasise the clinical importance of age and existing health conditions, especially diabetes, in affecting trichilemmal cyst development and the risk of infection. They provide new evidence for risk assessment, surgical planning and patient information.