Pilomatricoma in Turner Syndrome: Association with Renal Malformations and Analysis of the Vitamin D Pathway

Pilomatricoma is a rare benign cutaneous neoplasm that may occur more frequently in syndromic conditions such as Turner syndrome (TS). This study aimed to evaluate the prevalence and clinical characteristics of pilomatricoma and its association with clinical factors, serum vitamin D (VD) levels, and genetic variants in the VD pathway in patients with TS. Clinical variables and serum VD levels were obtained from medical records, and single-nucleotide variants in the GC, NADSYN1, and VDR genes were analyzed by allelic discrimination using real-time polymerase chain reaction. Among 97 patients with TS, six cases of histopathologically confirmed pilomatricoma were identified, corresponding to a prevalence of 6.2%, with lesions predominantly located on the head and upper extremities. Four patients (66.7%) had renal malformations. In exploratory multivariable analysis, renal malformations were significantly associated with pilomatricoma (adjusted OR = 14.2; 95% CI: 2.1–95.4; nominal p = 0.008; FDR-adjusted p = 0.032). No significant associations were observed with serum VD levels or the analyzed genetic variants. These findings suggest that pilomatricoma may be more frequent in TS than previously reported and identify an exploratory association between pilomatricoma and renal malformations. Given the small number of pilomatricoma cases, this association requires confirmation in larger independent cohorts.