DNA mismatch repair defects and microsatellite instability status in periocular sebaceous carcinoma

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 (β-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.

A retrospective cohort study of genetic referral and diagnosis of lynch syndrome in patients with cutaneous sebaceous lesions

Immunohistochemistry (IHC) of cutaneous sebaceous lesions (SL) can be used to screen patients for Lynch syndrome (LS). There is little data on rates of genetic referral and outcomes of genetic testing for patients with SL. This single-center retrospective study characterizes 400 + patients with SL, including IHC results, genetics referrals, and outcomes of genetic testing. Retrospective chart reviews were performed for patients with a pathology-confirmed diagnosis of SL at the University of Michigan between January 2009 and December 2019. 447 patients with 473 SL were identified. Excluding 20 patients with known LS, IHC was conducted in 173 (41%) patients. 92/173 (53%) patients had abnormal results. 69 of these 92 (75%) patients were referred to genetics. 32 additional patients were referred with normal IHC (n = 22) or without IHC (n = 10). Of 101 patients referred, 65 (64%) were seen and 47 (47%) completed genetic testing. 7/47 (15%) had pathogenic variants associated with LS, six with concordant abnormal IHC and one without IHC. Cancer genetics referral of patients with SL, particularly for lesions with abnormal IHC, yields a significant rate of LS diagnosis. Providers should consider genetics referral for patients with SL.

Expression of Programmed Cell Death-L1 (PD-L1) Protein and Mismatch Repair Mutations in Orbital Tumours-a Pilot Study

PURPOSE

Programmed cell death protein 1 (PD-1) and DNA mismatch repair (MMR) deficiency play an important role in tumour progression and response to treatment.Both markers have been studied in some ocular tumours but little is known about these markers in orbital tumours. This pilot study reports on PD-L1 expression and MMR mutations using next generation sequencing (NGS) in specific orbital tumours.

METHODS

We reviewed surgical specimens from patients with rhabdomyosarcoma, adenoid cystic carcinoma (ACC), pleomorphic adenoma (PA) and biopsy negative tissue from orbital tumours used as a control. immunohistochemistry (IHC) was performed on Formalin fixed paraffin embedded tissue using a PD-L1 antibody. DNA was extracted for targeted gene panel NGS of the MMR genes PMS2, MLH1, MSH6 and MSH2.

RESULTS

The study included 17 orbital specimens. Scattered membrane PD-L1 staining was noted in 3/6 rhabdomyosarcoma specimens without an accompanying lymphocytic infiltrate. PD-L1 immunostaining was absent in 3/3 ACC, and 5/6 PA specimens. PD-L1 immunostaining was not detected in 2/2 control specimens. 4/17 samples shared the same pathogenic mutation in the MLH1 gene, including 3/6 rhabdomyosarcoma and 1/3 ACC samples. 1/6 PA samples had a mutation in MSH6.

CONCLUSIONS

Our study demonstrated scattered, non-quantifiable or absent PD-L1 staining in a limited sample of orbital tumours suggesting that PD-1/PD-L1 inhibitor therapy may not be useful in treatment of malignant orbital tumours (rhabdomyosarcoma and ACC) when refractory to conventional therapy. Our pilot study suggest that PD-L1/MMR axis might not play a major role in the pathogenesis of primary orbital tumour.

Validation of Long Mononucleotide Repeat Markers for Detection of Microsatellite Instability

Mismatch repair deficiency (dMMR) predicts response to immune checkpoint inhibitor therapy in solid tumors. Long mononucleotide repeat (LMR) markers may improve the interpretation of microsatellite instability (MSI) assays. Our cohorts included mismatch repair (MMR) proficient and dMMR colorectal cancer (CRC) samples, MMR proficient and dMMR endometrial cancer (EC) samples, dMMR prostate cancer samples, MSI-high (MSI-H) samples of other cancer types, and MSI-low (MSI-L) samples of various cancer types. MMR status was determined by immunohistochemical staining and/or MSI Analysis System Version 1.2 (V1.2). The sensitivity and specificity of the LMR MSI panel for dMMR detection were both 100% in CRC. The sensitivity values of the MSI V1.2 and LMR MSI panels in EC were 88% and 98%, respectively, and the specificity values were both 100%. The sensitivity of the LMR panel was 75% in dMMR prostate cancer detected by immunohistochemistry. The 22 samples of other cancer types that were previously classified as MSI-H were also classified as MSI-H using the LMR MSI panel. For the 12 samples that were previously classified as MSI-L, 1 sample was classified as microsatellite stable using the LMR MSI panel, 8 as MSI-L, and 3 as MSI-H. The LMR MSI panel showed high concordance to the MSI V1.2 panel in CRC and greater sensitivity in EC. The LMR MSI panel improves dMMR detection in noncolorectal cancers.

Twenty-Eight Cases of Extraocular Sebaceous Carcinoma: A Correlative Clinicopathological and Immunohistochemical Analysis of Extraocular Sebaceous Carcinomas and Benign Sebaceous Gland Tumors

ABSTRACT

Extraocular sebaceous carcinoma (ESC) is a rare appendiceal skin tumor. In contrast to ocular sebaceous carcinoma, information about the exact cellular architecture of these lesions is scarce and the histogenesis of ESC is unknown. Here, we extend our previous study and investigate 28 extraocular carcinomas in comparison to 54 benign sebaceous tumors and 8 cases of normal sebaceous glands using a broad spectrum of antibodies against p63, several keratins, adipophilin, EMA, Ki67, androgen receptor, and mismatch repair proteins. This observational study demonstrates that p63- and K5/14-positive basaloid cells are key cells in normal sebaceous gland and in all sebaceous tumors and that these basaloid cells give rise to EMA+, adipophilin+ sebocytes, and K5/14+, K7±, K10± ductal structures. Finally, about half of ESC is associated with superficial in situ neoplasia, which provides evidence that at least part of these carcinomas arises from flat superficial in situ carcinoma. In contrast to the normal sebaceous gland, about half of all sebaceous tumors lack keratin K7. MMR protein IHC-profiles role will be discussed.

Muir-Torre Syndrome Associated Periocular Sebaceous Neoplasms: Screening Patterns in the Literature and in Clinical Practice

Background

Muir-Torre syndrome (MTS) is defined clinically as the association of cutaneous sebaceous neoplasm and visceral malignancy. Ancillary tests are considered crucial for diagnosis. Although screening guidelines for MTS, including the Mayo MTS scoring system, have been proposed, there are no ophthalmic site-specific guidelines.

Summary

A literature review conducted by PubMed search for articles describing patients with periocular sebaceous neoplasm and MTS disclosed 31 publications describing 60 patients, 36 (60%) of whom fulfilled clinical criteria for MTS, 6 (10%) whose diagnosis was based on screening ancillary studies, 14 (23%) who fulfilled clinical criteria and had supporting screening ancillary studies, and 4 (7%) who fulfilled clinical criteria and had supporting diagnostic genetic testing. Most patients were male (34 vs. 15 females), with a median age of 59 years (range 37-79 years). The most common diagnosis was sebaceous carcinoma (40/60, 67%), followed by sebaceous adenoma (16/60, 27%), followed by other tumors with sebaceous differentiation (4/60, 6%). The periocular lesions were identified prior to visceral malignancy in 10 out of 45 (22%) cases, after visceral malignancy in 34 out of 45 (76%) cases, and concurrently with visceral malignancy in 1 out of 45 (2%) cases. Immunohistochemistry for mismatch repair proteins was performed in 41 out of 60 (68%) and 14 out of 38 (37%) of the tumors had lost MSH2. Based on Mayo-MTS scores of 2 or greater, and after removing visceral malignancies not included in their scoring algorithm, 26 out of 30 of patients (87%) with complete data were considered to be appropriate candidates for further work-up. A survey of current practice was conducted by questionnaires, distributed to ophthalmic pathologists, ocular oncologists, and oculoplastic surgeons from national and international professional societies. Of the 103 physicians who participated in the survey, 91 (88%) felt that MTS evaluation guidelines were not sufficiently clear.

Key Messages

Our findings suggest that Mayo MTS screening guidelines may be applicable to periocular sebaceous neoplasms. The uncertainty of ophthalmic specialists about optimal screening guidelines for MTS reflects the heterogeneity of defining criteria for MTS and limited molecular genetic data. Larger studies with detailed clinical, histopathologic, and molecular genetic data are required to formally assess screening guidelines for MTS in patients with periocular sebaceous neoplasms.

Prevalence and molecular characteristics of DNA mismatch repair protein-deficient sebaceous neoplasms and keratoacanthomas in a Japanese hospital-based population

Background

Muir-Torre syndrome (MTS) is currently considered as a clinical variant of Lynch syndrome (LS). The clinical significance of the screening of patients with MTS-associated cutaneous tumors for the identification of LS has not yet been established. In addition, the prevalence and molecular characteristics of mismatch repair (MMR) protein deficiency in such tumors has scarcely been investigated in the Japanese population.

Methods

Immunohistochemistry (IHC) for MMR proteins (MLH1, MSH2, MSH6 and PMS2) was performed in formalin-fixed paraffin-embedded sections prepared from 16 sebaceous neoplasms (SNs) resected from 13 patients and 32 keratoacanthomas (KAs) resected from 31 patients at our institution between January 2005 and March 2014. Tumors showing MMR protein loss were further subjected to genetic analysis for detecting the presence of germline and/or somatic alterations of the MMR genes to identify the precise molecular mechanisms underlying the protein loss.

Results

Among the 16 SNs resected from 13 patients, eight SNs resected from five patients (38.5%) showed loss of expression of MMR proteins (MLH1/PMS2 loss, one patient; MSH2/MSH6 loss, four patients). Genetic analyses showed a pathogenic germline MSH2 mutation in one patient, somatic hypermethylation of the MLH1 promoter region in one patient, and somatic alterations of MSH2 without detectable germline mutations of MSH2 in three patients. None of the KAs examined in the study showed any loss of MMR protein expression.

Conclusions

The efficacy of routine screening of cutaneous neoplasms known to be associated with MTS by IHC for MMR proteins to identify LS may be fairly limited. MMR protein loss as determined by IHC in SNs is not always diagnostic of LS, and appears, in most cases, to be a result of somatic inactivation of the MMR genes.

Update on conjunctival pathology

Conjunctival biopsies constitute a fairly large number of cases in a typical busy ophthalmic pathology practice. They range from a single biopsy through multiple mapping biopsies to assess the extent of a particular pathological process. Like most anatomical sites, the conjunctiva is subject to a very wide range of pathological processes. This article will cover key, commonly encountered nonneoplastic and neoplastic entities. Where relevant, sections will include recommendations on how best to submit specimens to the ophthalmic pathology laboratory and the relevance of up-to-date molecular techniques.

Review of the current medical literature and assessment of current utilization patterns regarding mismatch repair protein immunohistochemistry in cutaneous Muir-Torre syndrome-associated neoplasms

Muir-Torre syndrome is a clinical variant of Lynch syndrome defined by the synchronous or metachronous occurrence of at least one sebaceous neoplasm and at least one Lynch syndrome-related internal cancer. Although screening guidelines for patients with colorectal carcinomas have been established, screening guidelines for cutaneous Muir-Torre associated neoplasms are not currently available. As such, we reviewed the current evidence for the use of MLH1, MSH2, MSH6 and PMS2 immunohistochemistry when cutaneous Muir-Torre associated neoplasms are encountered. We identified weak to moderate support overall for the global use of these assays, with some evidence suggesting a tailored approach using clinical parameters as an adjunct. We also assessed the current utilization patterns of attendees of the American Society of Dermatopathology Annual Meeting (Chicago, 2016). We found that 91% of respondents utilize mismatch repair immunohistochemistry, with the majority utilizing these tests only when requested by the submitting clinician.

Sebaceous Carcinoma of the Eyelid

BACKGROUND

Periocular sebaceous carcinoma (PSC) is a rare but aggressive neoplasm that tends to clinically and histopathologically mimic other conditions. PSC can be challenging to diagnose using histomorphology alone given its overlap with 2 more common tumors that occur in this area (basal cell carcinoma [BCC] and squamous cell carcinoma [SCC]). Use of immunohistochemistry can help resolve this differential diagnosis.

METHODS

A review of the literature was performed, focusing on the epidemiology, morphology, and immunohistochemical features of PSC.

RESULTS

The most useful immunostains in the differential diagnosis of PSC are epithelial membrane antigen, Ber-Ep4, androgen receptor (AR), and adipophilin. To discern PSC from BCC, one should use EMA, Ber-Ep4, AR, and adipophilin, whereas discerning PSC from SCC can be achieved by evaluating AR and adipophilin. In addition, p53 and ERBB2 (formally known as HER2/neu) are other potentially useful immunohistochemical markers for the differential diagnosis of PSC.

CONCLUSIONS

Use of new immunohistochemical techniques, as well as the elucidation of molecular alterations, such as the presence of ERBB2 amplification, will advance our understanding of PSC.

Sebaceous adenomas of the eyelid and Muir-Torre Syndrome

BACKGROUND/AIMS

Sebaceous adenomas (SAs) are rare, benign sebaceous gland tumours of the eyelid. SAs may be associated with primary internal malignancies. This association is known as Muir-Torre Syndrome (MTS). The purpose of this study was to approximate the prevalence of SAs, to determine the reliability of the clinical diagnosis of SAs and to demonstrate immunohistochemical staining of DNA mismatch repair proteins mutL homologue 1 (MLH1) and mutS homologue 2 (MSH2) for a case of MTS.

METHODS

We reviewed the histopathology reports from all eyelid specimens collected between 1993 and 2013 at the Henry C Witelson Ocular Pathology Laboratory to determine the proportion of SAs. For the SAs identified on histopathology, we looked at patient charts to see what diagnosis was originally suspected on clinical examination. Immunohistochemical staining for MLH1 and MSH2 was performed on all SAs to screen for MTS.

RESULTS

Of the 5884 eyelid specimens collected, 9 were SAs (6 women, 3 men; 42-72 years old). The diagnosis of SA was suspected clinically in only one of the nine cases based on the gross appearance of the eyelid lesion. Immunohistochemistry revealed one SA case with positive MLH1 expression and negative MSH2 expression. These findings prompted systemic work-up and this patient was diagnosed with MTS after discovery of a colon adenocarcinoma T2M0N0.

CONCLUSIONS

The diagnosis of eyelid SA is rare. The importance of this benign eyelid tumour stems from its association with internal malignancies in MTS. Immunohistochemical staining of mismatch repair proteins MLH1 and MSH2 is a valid and accessible strategy for investigating MTS in patients with SAs.

[Differential diagnostics of sebaceous tumors]

Sebaceous tumors are epithelial tumors with a differentiation towards sebaceous adnexal structures of the skin. They imitate the epithelial cells of mature sebaceous glands, sebaceous ducts, immature (embryonic) sebaceous structures or sebaceous glands that are not stimulated by hormones (mantle structures). This article explains the classification of sebaceous tumors on the basis of the normal histology of sebaceous glands. Clinical and histopathological criteria are given for the most important sebaceous tumors. The differential diagnosis of sebaceoma, sebaceous adenoma and various types of sebaceous carcinoma is emphasized. The importance of a specific diagnosis of adnexal tumors is demonstrated by tumor-associated syndromes with involvement of other organs (e.g., Muir-Torre syndrome and Birt-Hogg-Dubé syndrome). Furthermore, conceptional controversies, problems in differential diagnosis and the impact of immunohistochemical staining in the assessment of sebaceous tumors are considered.