Molecular landscape of eyelid sebaceous gland carcinoma: A comprehensive review.

Eyelid sebaceous gland carcinoma (SGC) is an aggressive skin cancer characterized by a heightened risk of recurrence and metastasis. While surgical excision is the primary treatment, unraveling the molecular intricacies of SGC is imperative for advancing targeted therapeutic interventions and enhancing patient outcomes. This comprehensive review delves into the molecular landscape of eyelid SGC, emphasizing key genetic alterations, signaling pathways, epigenetic modifications, and potential therapeutic targets. Significant findings include aberrations in critical signaling pathways (ß-catenin, lymphoid enhancer binding factor, hedgehog, epidermal growth factor receptor, P53, and P21WAF1) associated with SGC progression and poor prognosis. Notably, eyelid SGC manifests a distinctive mutational profile, lacking ultraviolet signature mutations in tumor protein 53 (TP53), indicating alternative mutagenic mechanisms. Next-generation sequencing identifies actionable mutations in genes such as phosphatase and tensin homolog (PTEN) and Erb-B2 receptor tyrosine kinase 2 (ERBB2), facilitating the emergence of personalized medicine approaches. Molecular chaperones, specifically X-linked inhibitor of apoptosis protein (XIAP) and BAG3, emerge as pivotal players in promoting tumor survival and proliferation. The review underscores the role of epithelial-mesenchymal transition, where regulators like E-cadherin, vimentin, and ZEB2 contribute to SGC aggressiveness. Epigenetic modifications, encompassing DNA methylation and microRNA dysregulation, further elucidate the molecular landscape. This review consolidates a comprehensive understanding of the molecular drivers of eyelid SGC, shedding light on potential therapeutic targets and providing a foundation for future investigations in diagnostic, prognostic, and personalized treatment strategies for this formidable malignancy.

Bilateral development of biclonal ocular adnexal marginal zone lymphoma at a 2-year interval.

Ocular adnexal marginal zone B-cell lymphoma (OAMZL) of the mucosa-associated lymphoid tissue is a distinct subtype of B-cell lymphoma. OAMZL occasionally occurs on both sides with a varied sequence in the time course. However, few case reports have described clonal analysis of bilateral OAMZ. Here we present a case of biclonal OAMZL, that developed bilaterally at a 2-year interval. A 38-year-old woman was diagnosed with OAMZL in the right lower eyelid conjunctiva and received local radiation therapy, resulting in the disappearance of the tumor. Two years later, she developed another tumor in the left lower eyelid and was diagnosed with relapse of OAMZL. She was re-treated successfully with radiation therapy. Analysis of immunoglobulin (Ig) gene rearrangement in the bilateral tumor samples showed different clonotypic VDJ recombination within the Ig heavy chain gene and different patterns of rearrangement of the Ig light chain genes. The results indicated that independent B-cell clones causing the specific subtype of lymphoma had generated in both eyes. The biclonal nature of the lymphoma that developed sequentially in the same anatomic site in this case suggests that underlying inherent or environmental factors may lead to ongoing emergence of new tumor clones.

Establishment and Characterization of a TP53-Mutated Eyelid Sebaceous Carcinoma Cell Line.

Purpose: Eyelid sebaceous carcinoma (SeC) is the third most frequent eyelid malignancy worldwide and is relatively prevalent in Asian patients. An eyelid SeC cell line model is necessary for experimental research to explore the etiology and pathogenesis of eyelid SeC. This study established and characterized an eyelid SeC cell line with a TP53 mutation that might be useful for analyzing potential treatment options for eyelid SeC. Methods: The eyelid SeC cell line SHNPH-SeC was obtained from a patient with eyelid SeC at Shanghai Ninth People's Hospital (SHNPH), Shanghai JiaoTong University School of Medicine. Immunofluorescence staining was employed to detect the origination and proliferation activity. Short tandem repeat (STR) profiling was performed for verification. Chromosome analysis was implemented to investigate chromosome aberrations. Whole exome sequencing (WES) was used to discover genomic mutations. Cell proliferation assays were performed to identify sensitivity to mitomycin-C (MMC) and 5-fluorouracil (5-FU). Results: SHNPH-SeC cells were successively subcultured for more than 100 passages and demonstrated rapid proliferation and migration. Karyotype analysis revealed abundant chromosome aberrations, and WES revealed SeC-related mutations in TP53, KMT2C, and ERBB2. An in vivo tumor model was successfully established in NOD/SCID mice. Biomarkers of eyelid SeC, including cytokeratin 5 (CK5), epithelial membrane antigen (EMA), adipophilin, p53, and Ki-67, were detected in SHNPH-SeC cells, original tumors, and xenografts. MMC and 5-FU inhibited the proliferation and migration of SHNPH-SeC cells, and SHNPH-SeC cells presented a greater drug response than non-TP53-mutated SeC cells. Conclusions: The newly established eyelid SeC cell line SHNPH-SeC demonstrates mutation in TP53, the most commonly mutated gene in SeC. It presents SeC properties and malignant characteristics that may facilitate the investigation of cellular behaviors and molecular mechanisms of SeC to explore promising therapeutic strategies.

Integrated Whole-Exome and Transcriptome Sequencing Indicated Dysregulation of Cholesterol Metabolism in Eyelid Sebaceous Gland Carcinoma.

Purpose: To identify the molecular background of eyelid sebaceous gland carcinomas (SCs), we conducted the integrated whole-exome sequencing and transcriptome sequencing for eyelid SCs in this study. Methods: The genetic alterations were studied by whole-exome sequencing, and the messenger RNA expression was studied using Oxford Nanopore Technologies (ONT) in five paired fresh eyelid SC tissues and adjacent normal tissues. Integrated analysis of exome and transcriptomic information was conducted for filtering candidate driver genes. Protein-protein interaction (PPI) network of filtered candidate genes was analyzed by STRING. The protein expression was verified by immunohistochemistry in 29 eyelid SCs and 17 compared normal sebaceous gland tissues. Results: The average numbers of pathogenic somatic single-nucleotide variants (SNVs) and indels in eyelid SCs were 75 and 28, respectively. Tumor protein p53 (TP53), zinc finger protein 750 (ZNF750), filaggrin 2 (FLG2), valosin-containing protein (VCP), and zinc finger protein 717 (ZNF717) were recurrent mutated genes. A mean of 844 differentially expressed genes (DEGs) were upregulated, and 1401 DEGs were downregulated in SC samples. The intersection of DEG-based pathways and mutation-based pathways was mainly involved in microbial infection and inflammation, immunodeficiency, cancer, lipid metabolism, and the other pathways. The intersection of DEGs and mutated genes consisted of 55 genes, of which 15 genes formed a PPI network with 4 clusters. The PPI cluster composed of scavenger receptor class B member 1 (SCARB1), peroxisome proliferator-activated receptor γ (PPARG), peroxisome proliferator-activated receptor γ coactivator 1α (PPARGC1A) was involved in cholesterol metabolism. The expression of SCARB1 protein was found to be increased, whereas that of PPARG protein was decreased in eyelid SCs compared to that in the normal sebaceous glands. Conclusions: Increased SCARB1 and decreased PPARG indicated that dysregulation of cholesterol metabolism might be involved in carcinogenesis of eyelid SCs. Translational Relevance: The malfunction in cholesterol metabolism might advance our knowledge of the carcinogenesis of eyelid SCs.

Periocular Pigmented Basal Cell Carcinomas: Clinicopathologic Features and Mutational Profile.

PURPOSE: Pigmented basal cell carcinomas (PBCC) is an uncommon variant of basal cell carcinoma of the periocular region with limited information in the literature. We highlight the clinicopathological profile and somatic mutations in periocular PBCC. METHODS: The clinicopathological features and somatic mutations in patients with periocular PBCC were examined and compared with periocular non-PBCC reported in the literature. Next-generation sequencing panel analysis for the excised tumors identified somatic mutations. RESULTS: In a total of 31 patients, PBCC was common in females (54%; p = 0.03); as a unilateral lower eyelid (n = 22; 71%), solitary mass (n = 30; 98%). Pathologic subtypes were variable. Most were nodular or mixed variants (n = 23; 74%). During the follow up (2.5-4.5 years), 1 patient (3.5%) had a recurrence. The clinical and pathologic features of PBCC were similar to those reported in nonperiocular locations. Somatic mutations detected in 25/31 tumors. Variants in 50/161 genes in the panel were noted. PTCH1 (14/31), TERT (12/31), and SMO (7/31) variants were common. Fifteen patients had novel drivers, including POLE, FANCD2, and CREBBP. SMO mutations were significantly more common in females (7/7), lower eyelid (5/7), and TERT mutations were more common in nodular subtype (10/12). CONCLUSIONS: In this large cohort of a relatively uncommon variant of BCC, the clinicopathological features and tumor behavior of PBCC was similar to periocular non-PBCC. The somatic mutation spectrum of PBCC resembles that reported in nonperiocular cutaneous BCC with novel drivers identified. We identified several potential actionable mutations that could be targeted with molecular therapy.

A novel DDB2 mutation causes defective recognition of UV-induced DNA damages and prevalent equine squamous cell carcinoma.

Squamous cell carcinoma (SCC) occurs frequently in the human Xeroderma Pigmentosum (XP) syndrome and is characterized by deficient UV-damage repair. SCC is the most common equine ocular cancer and the only associated genetic risk factor is a UV-damage repair protein. Specifically, a missense mutation in horse DDB2 (T338M) was strongly associated with both limbal SCC and third eyelid SCC in three breeds of horses (Halflinger, Belgian, and Rocky Mountain Horses) and was hypothesized to impair binding to UV-damaged DNA. Here, we investigate DDB2-T338M mutant's capacity to recognize UV lesions in vitro and in vivo, together with human XP mutants DDB2-R273H and -K244E. We show that the recombinant DDB2-T338M assembles with DDB1, but fails to show any detectable binding to DNA substrates with or without UV lesions, due to a potential structural disruption of the rigid DNA recognition ß-loop. Consistently, we demonstrate that the cellular DDB2-T338M is defective in its recruitment to focally radiated DNA damages, and in its access to chromatin. Thus, we provide direct functional evidence indicating the DDB2-T338M recapitulates molecular defects of human XP mutants, and is the causal loss-of-function allele that gives rise to equine ocular SCCs. Our findings shed new light on the mechanism of DNA recognition by UV-DDB and on the initiation of ocular malignancy.

Bioinformatics analysis of the microRNA-mRNA network in sebaceous gland carcinoma of the eyelid.

Sebaceous gland carcinoma (SGC) of the eyelid is an uncommon aggressive tumor with a relatively high rate of local recurrence and a poor prognosis following metastasis. However, the molecular mechanisms underlying the pathogenesis of SGC remain unclear. The purpose of the present study was to clarify microRNA (miRNA) expression profiles in SGC and to explore novel miRNA­mRNA networks of SGC. A small RNA­sequencing analysis was performed to identify miRNAs differentially expressed between SGC and sebaceous adenoma control samples. Bioinformatics analyses were conducted to reveal biological functions, canonical pathways and molecular interaction networks using integrated miRNA­mRNA datasets, including mRNA expression profiles of SGC from our previous study. The present results demonstrated that 16 upregulated miRNAs and 516 downregulated mRNAs were associated with loss of lipid metabolism function and enriched in cholesterol biosynthesis pathways. By contrast, 29 downregulated miRNAs and 194 upregulated mRNAs were mainly associated with the promotion of cell survival and proliferation in addition to enrichment of DNA damage­induced cell cycle­regulation pathways. Furthermore, network analyses revealed that the upregulated miRNAs, miR­130a­3p and miR­939­5p, and the downregulated miRNAs, miR­146a­5p, miR­149­3p, miR­193a­3p, miR­195­5p and miR­4671­3p, could be upstream regulators related to these functional changes of SGC. These results improved the understanding of molecular mechanisms of SGC and may help to improve the diagnosis of SGC.

Molecular profiling of a primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid.

Primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid is a rare and aggressive neoplasm. Fewer than 50 cases have been reported in the literature, and the genetic driving mutations are unknown. Herein, we present a case of this rare disease along with the results of molecular profiling via targeted next-generation sequencing. The patient is an 85-year-old man who presented with left eyelid swelling initially thought to be a chalazion. After no response to incision and drainage and antibiotics, an incisional biopsy was performed. Histopathologic sections revealed a proliferation of cells with signet-ring and histiocytoid morphology arranged singly and in cords infiltrating the dermis, subcutaneous tissue, and muscle. The lesional cells strongly expressed cytoplasmic cytokeratin 7 and nuclear androgen receptor. Next-generation sequencing revealed a CDH1 mutation, which is known to confer signet-ring morphology in other carcinomas. Pathogenic mutations in NTRK3, CDKN1B, and PIK3CA were also detected. To our knowledge, this is the first documented genetic analysis of this rare disease with findings that offer insights into disease pathogenesis and potential therapeutic targets.

Whole-exome sequencing for ocular adnexal sebaceous carcinoma suggests PCDH15 as a novel mutation associated with metastasis.

Ocular adnexal sebaceous carcinoma (OASeC) is an aggressive eyelid carcinoma. Analysis of molecular-genetic drivers of this disease could reveal new prognostic markers and actionable targets for treatment. To identify somatically acquired genomic mutations in OASeC and explore their associations with metastasis, whole-exome sequencing on DNA extracted from retrospectively collected tumor samples was performed. Thirty-one patients in two orbital oncology centers with OASeC were included. Sequencing results were analyzed to detect mutations and explore their possible association with metastasis. The median patient age was 64 years. A total of 1780 candidate somatic mutations were identified with median mutation rate of 1.0/Mb (range, 0.2-13.6). The five most commonly mutated genes (as determined by MutSig; q value < 0.25) were TP53 (mutated in 22 cases), ZNF750 (13 cases), RB1 (12 cases), NOTCH1 (8 cases), and PCDH15 (5 cases). Mutations in ZNF750 or NOTCH1 pathway genes were present in 24 (77%) of the 31 cases; there was a trend toward mutual exclusivity of ZNF750 and NOTCH1 mutations. All eight tumors with NOTCH1 mutations also had TP53 and/or RB1 mutations. Four of the five PCDH15 mutations and all four PCDH15 missense mutations were identified in patients with metastatic disease, including one patient with distant metastasis and three with nodal metastasis. PCDH15 was significantly associated with metastasis (P = 0.01). We identified the most commonly mutated genes in a series of OASeCs and found a previously unreported mutation in OASeC, PCDH15 mutation, that was significantly associated with metastasis. NOTCH1 mutation is an actionable mutation; clinical trials targeting this mutation are available throughout the US and could be considered for patients with metastatic NOTCH1-mutant OASeC. TP53, ZNF750, RB1, and PCDH15 mutations are most likely loss-of-function mutations and may have diagnostic and prognostic importance.

Vimentin overexpression as a novel poor prognostic biomarker in eyelid sebaceous gland carcinoma.

BACKGROUND: Vimentin is an intermediate-sized filament which is highly expressed in mesenchymal cells and is associated with epithelial-mesenchymal transition (EMT). EMT markers ZEB2 and Slug lead to Vimentin overexpression and E-cadherin loss, resulting in invasion and metastasis. However, the status of Vimentin remains unexplored in eyelid sebaceous gland carcinoma (SGC). The study aims to determine status of Vimentin in SGC and its association with EMT markers E-cadherin, ZEB2 and Slug. METHODS: Vimentin protein expression was undertaken in 66 cases with SGC by immunohistochemistry (IHC). Messenger RNA (mRNA) expression was determined in 42 fresh tissues by quantitative real-time PCR. Association of Vimentin with E-cadherin, ZEB2 and Slug was also analysed. Patients were followed up for 17-69 months (mean 34.02 ± 14.73 months). RESULTS: IHC revealed Vimentin overexpression in 37/66 (56%) cases. This overexpression showed significant association with lymph node metastasis (p=0.004) and pagetoid spread (p=0.05). Patients with high Vimentin expression also had poor disease-free survival (p=0.033). Univariate Cox regression model indicated that high Vimentin expression (p=0.043) and advanced tumour stage (p=0.002) were independent adverse prognostic factors. High Vimentin mRNA expression was seen in 16/42 (38%) cases and correlated significantly with lymph node metastasis (p=0.027), advanced tumour stage (p=0.002) and large tumour size (p=0.023). Vimentin expression overall showed a significant inverse association with E-cadherin and direct association with ZEB2 expression. CONCLUSIONS: Vimentin overexpression in SGC is associated with EMT and leads to poor clinical outcome. It also emerged as a novel predictor for lymph node metastasis and poor survival.

CDKN2A, CDK1, and CCNE1 overexpression in sebaceous gland carcinoma of eyelid.

PURPOSE: To investigate the overexpression of genes in sebaceous gland carcinoma (SGC) of the eyelid compared to sebaceous adenoma of the eyelid in order to elucidate the molecular mechanism underlying pathogenesis. METHODS: We performed histopathological examination of eyelid tissues surgically removed from four patients diagnosed with SGC (cases 1-3) and sebaceous adenoma (case 4) of the eyelid. Next, we performed global gene expression analysis of surgical tissue samples using a GeneChip® system and the Ingenuity Pathways Knowledge Base. The results of the GeneChip® analysis were explored with quantitative real-time polymerase chain reaction (qRT-PCR) analysis. RESULTS: In the SGC samples, we found that 211, 199, and 199 genes, respectively, showed ≥ 2.0-fold higher expression than those in the sebaceous adenoma sample (case 4); 194 genes were common to all three SGC samples. For the 194 genes with upregulated expression, functional category analysis showed that SGC of the eyelid employed a unique gene network, including cyclin-dependent kinase inhibitor 2A (CDKN2A), cyclin-dependent kinase 1 (CDK1), and cyclin E1 (CCNE1), which are related to cell cycle progression, incidence of tumor, and cell viability. Furthermore, qRT-PCR analysis showed that the expression levels of CDKN2A, CDK1, and CCNE1 were significantly upregulated in all SGC cases compared to those in the sebaceous adenoma case. These data were similar to the results of microarray analysis. CONCLUSION: Overexpression of cell cycle-related genes CDKN2A, CDK1, CCNE1, and their gene network may help elucidate the pathogenic pathway of SGC of the eyelid at the molecular level.

MicroRNA and transcriptome analysis in periocular Sebaceous Gland Carcinoma.

Sebaceous gland carcinoma (SGC) is a rare, but life-threatening condition with a predilection for the periocular region. Eyelid SGC can be broadly categorised into two subtypes, namely either nodular or pagetoid with the latter being more aggressive and requiring radical excision to save life. We have identified key altered microRNAs (miRNA) involved in SGC shared by both subtypes, hsa-miR-34a-5p and hsa-miR-16-5p. However, their gene targets BCL2 and MYC were differentially expressed with both overexpressed in pagetoid but unchanged in nodular suggesting different modes of action of these two miRNAs on BCL/MYC expression. Hsa-miR-150p is nodular-specifically overexpressed, and its target ZEB1 was significantly downregulated in nodular SGC suggesting a tumour suppressor role. Invasive pagetoid subtype demonstrated specific overexpression of hsa-miR-205 and downregulation of hsa-miR-199a. Correspondingly, miRNA gene targets, EZH2 (by hsa-miR-205) and CD44 (by hsa-miR-199a), were both overexpressed in pagetoid SGC. CD44 has been identified as a potential cancer stem cell marker in head and neck squamous cell carcinoma and its overexpression in pagetoid cells represents a novel treatment target. Aberrant miRNAs and their gene targets have been identified in both SGC subtypes, paving the way for better molecular understanding of these tumours and identifying new treatment targets.

Immunohistochemical evaluation of stress-responsive protein sestrin2 and its correlation with p53 mutational status in eyelid sebaceous gland carcinoma.

BACKGROUND: p53 is a stress-activated tumour suppressor gene, and its mutation has been associated with solid tumours including non-melanoma skin cancers. Sestrin2 expression is associated with DNA damage and oxidative stress and has been described as a downstream target of p53 network. However, its role in sebaceous gland carcinoma (SGC) remains unexplored. OBJECTIVES: To determine the role of p53 and its downstream target gene sestrin2 expression and p53 gene mutation status in SGC. METHODS: Twenty cases of eyelid SGC tumour and circulating cell-free DNA (ccfDNA) were subjected to mutational analysis of p53 gene. p53 and sesrin2 expression was evaluated by immunohistochemistry. Results were correlated with the clinicopathological features of eyelid SGC. RESULTS: p53 gene mutations was detected in 25% of the SGC cases. A C>T transition was identified in exon 6 in a single patient in both tumour and ccfDNA. A G>T transversion leading to amino acid change D259Y was seen in four patients. A splice site mutation affected a single case in exon 6. p53 expression was observed in 55% SGC. Loss of sestrin2 in 55% SGC cases correlated with poor tumour differentiation (P=0.0001), upper eyelid involvement (P=0.004), p53 mutation (P=0.039) and with mutant p53 expression (P=0.0001). CONCLUSION: Sestrin2 expression was found to be significantly reduced in p53 mutated SGC cases and in cases with strong p53 nuclear immunopositivity, suggesting that loss of sestrin2 may be of biological significance in the development of SGC and as a key downstream component of p53 tumour suppression network in eyelid SGC.

Case report of Schöpf-Schulz-Passarge syndrome resulting from a missense mutation, p.Arg104Cys, in WNT10A.

Schöpf-Schulz-Passarge syndrome (SSPS) is a rare ectodermal dysplasia characterized by cysts of the eyelids, hypodontia, hypotrichosis, palmoplantar keratosis and onychodystrophy, and it is not common in Asia according to the published work. This autosomal recessive disorder was believed to result from mutations in the WNT10A gene. We report a 54-year-old Taiwanese man with SSPS resulted from a homozygous mutation (p.Arg104Cys) in WNT10A. This mutation has not been reported in odonto-onycho-dermal dysplasia but was demonstrated to link with dental abnormalities. This report implies the significance of WNT10A gene mutation in ectodermal dysplasia and highlights the clinical features of SSPS.

Mammary Analog Secretory Carcinoma With ETV6 Rearrangement Arising in the Conjunctiva and Eyelid.

Mammary analog secretory carcinoma (MASC) of salivary gland is a recently described neoplasm that morphologically and immunohistochemically resembles secretory carcinoma of the breast. Genetically, both of them harbor ETV-6-NTRK-3 fusion rearrangement. One case of primary MASCs arising from the eyelid is reported. The patient was a 52-year-old man. Microscopically, the tumor exhibited nodular aggregation of solid, tubular, and microcystic/macrocystic structures. Characteristic "colloid-like" eosinophilic secretory material was present within intraluminal spaces. Immunohistochemically, the tumor cells were positive for mammaglobin, S-100, STAT5a, vimentin, GCDFP-15, AE1/AE3, EMA, and CK7 and were negative for DOG-1, CK5/6, and SMA. A dual color break-apart fluorescence in situ hybridization probe identified rearrangement of the ETV6 gene locus on chromosome 12. The patient had no history of breast or salivary gland tumor. The tumor was completely excised, and the patient has no evidence of recurrent disease or metastasis after 1-year follow-up. A diagnosis of primary MASC was rendered. MASC has never been reported occurring in ocular region. This type of secretory carcinoma probably originates from sweat glands or accessory lacrimal glands, Wolfring and Krause. This unique case expands the clinicopathologic landscape of MASCs for better characterization of this rare entity.

Mutation analysis of CTNNB1 gene and the ras pathway genes KRAS, NRAS, BRAF, and PIK3CA in eyelid sebaceous carcinomas.

Sebaceous carcinoma (SC) represents a rare, aggressive eyelid malignancy with poor prognosis and is a possible component of Muir-Torre syndrome. However, genetic features as driver mutations or potential therapeutic targets are not fully elucidated. Recent a few studies have shown that SCs have concurrently multiple mutations including RAS/RAF/MAPK and PI3K/Akt pathways via next-generation sequencing in western population. Because we recently demonstrated absence of KRAS mutations in Korean eyelid SCs, we extended our previous study to the analysis of NRAS, BRAF, PIK3CA, and CTNNB1 mutations, and the examination of related protein expressions in 15 eyelid SCs. Repeated molecular analysis by peptide nucleic acid-mediated PCR clamping method, PNA clamping-assisted fluorescence melting curve analysis, and direct sequencing revealed that all eyelid SCs had wild type alleles of NRAS, BRAF, and PIK3CA in hotspot exon locations. Only silent mutations in the CTNNB1 gene (p.Q61Q) were identified. Using immunohistochemistry and microsatellite instability analysis, they harbored all intact mismatch repair gene proteins with microsatellite stability. Membranous and cytoplasmic ß-catenin staining was found in all tumors, whereas the one third of those tumors showed cyclin D1 overexpression, of which 40% and 80% showed p53 expression and p16 expression, respectively. The lack of KRAS, NRAS, BRAF, and PIK3CA mutation in our study may suggest that a subset of eyelid SCs is unlike that of eyelid SCs of western countries. The mismatch repair gene proteins and microsatellite instability analysis as a screening test for Muir-Torre syndrome may be limited in the Korean eyelid SCs.