Epidemiological Features and Pathogenic Mechanisms of Steatocystoma Multiplex: A Systematic Review

Steatocystoma multiplex (SM) is a rare hereditary skin disorder arising from the pilosebaceous unit, clinically characterized by multiple asymptomatic sebum-containing cysts predominantly distributed on the chest, axillae, and upper arms. However, the epidemiological features and pathogenic mechanisms of SM remain poorly characterized.

A systematic search of PubMed, Embase, and CNKI was conducted for studies published between January 2003 and December 2023. Case reports and observational studies reporting individual-level clinical data on confirmed SM patients were eligible. Demographic, clinical, and genetic data were extracted and analyzed using appropriate statistical tests.

A total of 145 cases from 82 publications were included. SM showed no clear geographical or ethnic predilection. The median age at onset was 23 years and the median age at diagnosis was 31 years, reflecting a diagnostic delay of approximately 8 years. Familial cases (26.2%) had a significantly earlier age at onset (13.5 vs. 30.0 years, P < 0.001) and diagnosis (22.0 vs. 35.0 years, P < 0.001), and higher rates of infected lesions and nail dystrophy. Hidradenitis suppurativa was more prevalent in females (12.5% vs. 1.5%, P = 0.019), and sex-based differences in lesion distribution were observed. KRT17 was the most frequently mutated gene, with Arg94 as the predominant mutation site. KRT17 mutations are thought to impair cytoskeletal integrity within the pilosebaceous unit, while hormonal factors - particularly androgen-driven sebaceous gland activation during puberty - are implicated as additional modulators of disease onset and lesion distribution.

This review characterizes the epidemiological and clinical features of SM, demonstrating meaningful differences between familial and sporadic cases and between sexes. Genotype-phenotype discordance and KRT17-negative cases suggest that modifier genes and hormonal factors contribute to phenotypic determination. The substantial diagnostic delay highlights the need for improved clinical awareness, and mutation-targeted therapeutic strategies warrant further investigation.