Background: Eruptive syringoma (ES) is a clinical variant of the appendageal tumor syringoma. Around 75% of ES arise in the head or neck, which makes them unsightly. ES is common in patients with amyloidosis, diabetes, and Down's syndrome, suggesting that it may be associated with potential systemic effects. ES is a rare tumor with the unclear pathogenesis and no effective treatment. Methods: A PubMed search of ES was conducted. Plasma samples of patients with ES were acquired from the Department of Dermatology at Xi'an Jiaotong University's Second Affiliated Hospital. After removing highly abundant proteins, plasma samples were subjected to proteomics and metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: LC-MS/MS revealed 71 differentially expressed proteins and 18 differentially abundant metabolites. The functional analysis highlighted the importance of complement binding, coagulation, secretory granules and vesicle lumen. Further, the study revealed 15 hub genes associated with FGG, GC, APOE, FGA, FGB, C4A, C3, CRP, C4B, FLNA, TAGLN2, ANXA5, MYL6, MYL12B, and TLN1 organized into three clusters. The seed genes in each cluster were GC, FLNA, and MYL6. In addition, glycol metabolism was associated with variable abundance of serum metabolites, which explains the relatively high rate of ES among diabetics. Conclusion:This study suggests that immunological inflammation and tumor glycol metabolism may play significant role in the pathophysiology of ES.

Background: Epidermal cysts are common benign epithelial tumors. They are known to result from penetrating-type injuries or infection of human papillomavirus. The differential diagnosis commonly includes multiplex steatocystoma, lipoma, and neurofibroma. Pathological examination is essential for diagnosis, and surgical excision is the recommended treatment. Objective: We report a case in a man who presented with a cystic lesion on the scalp over 22 years to provide clinical evidence for mechanism of epidermal cysts. We conducted epidemiological analysis of 3949 patients with epidermal cysts to clarify the epidemiological characteristics and clinical features of epidermal cysts. Patients and Methods: A total of 3949 individuals with confirmed epidermal cysts were collected for analysis. Data were expressed as mean ± SEM and analyzed using Student's t-test. Results: Our data showed that the mean age of diagnosis of males was statistically earlier than that of females (P<0.001), but no significant difference in sex predilection was observed (P=0.55). The high incidence age of males and females was in the young and middle stage. Lesion locations were a bit different among age groups, but the face was the most common site of epidermal cyst at all age stages. Conclusion: Our case offers clinical evidence to the theory which refers trauma as one of the main causes of epidermal cysts in hairbearing area. According to analysis of large number of samples, we can further support the idea that epidermal cyst has equal sex predilection and mainly occurs on the young and middle-aged adults. It is usually solitary and most likely to be found on face and trunk.