An Intrapatient Concordance Study of Mismatch Repair Protein Immunohistochemical Staining Patterns in Patients With Muir-Torre Syndrome

Muir-Torre syndrome and recent updates on screening guidelines: The link between colorectal tumors and sebaceous adenomas in unusual locations

BACKGROUND

Muir-Torre syndrome (MTS) is a rare genetic disorder that is caused by mismatch repair (MMR) protein mutations. MTS increases the risk of developing skin and gastrointestinal tumors such as sebaceous adenomas (SAs), sebaceous carcinomas, colorectal cancer, endometrial cancer, and ovarian cancer. The risk of developing these types of tumors varies depending on the involved mutation and the individual's family history risk.

CASE PRESENTATION

A 47-year-old male presented with multiple skin lesions on the scalp, face, flank, and back. The examination revealed well-circumscribed, dome-shaped papules with a yellowish appearance with white oily material in the center. Histopathologic examination showed a well-circumscribed sebaceous neoplasm consistent with a mixture of basaloid cells and lobules of bland-appearing mature adipocytes that communicate directly to the surface epithelium. Focal cystic changes and peritumoral lymphocytic infiltrate were noted. Increased mitotic figures were seen in the basaloid cell component. The overall findings were consistent with the diagnosis of SAs. MMR staining showed preserved expression in MLH1 and PMS2 proteins, while MSH2 and MSH6 staining showed loss of protein expression. A screening colonoscopy showed numerous colon and rectal tumors, prompting concerns about the likelihood of MTS. Surgical intervention was pursued for complete resection. Histology revealed a diagnosis of mucinous adenocarcinoma/adenocarcinoma with mucinous features of the colon. The diagnosis of MTS was supported by molecular testing that revealed MSH2 germline mutation. The increased likelihood of MTS was attributed to the occurrence of SAs in unusual locations of the head and neck regions, unlike typical cases.

CONCLUSION

MTS is a rare clinical condition that necessitates prompt thorough evaluation and periodic surveillance. When SA is encountered in atypical locations, it is important to consider additional testing supported by immunohistochemical staining, molecular testing, and regular screening to exclude the likelihood of MTS.

Germline Testing of Mismatch Repair Genes Is Needed in the Initial Evaluation of Patients With Muir-Torre Syndrome-Associated Cutaneous Sebaceous Neoplasms: A Case Series

Muir-Torre syndrome, a subtype of Lynch syndrome, is characterized by a germline mutation of one or more mismatch repair genes such as MutL Homolog 1 (MLH1), MutS Homolog 2 (MSH2), MutS Homolog 6 (MSH6), and PMS1 Homolog 2, mismatch repair system component (PMS2) resulting in microsatellite instability and at least one malignancy and a minimum of one syndrome-associated sebaceous neoplasm such as a sebaceous adenoma, epithelioma, or carcinoma. The syndrome has an autosomal dominant mode of inheritance detectable with germline sequencing of normal body elements such as blood, saliva, or normal skin for a mismatch repair gene mutation. Sebaceous neoplasms can occur before, concurrent with, or following Muir-Torre syndrome-related cancer. Immunohistochemistry, microsatellite instability testing, and next-generation sequencing of tumor tissue can evaluate malignancies such as colorectal and endometrial cancer and sebaceous neoplasms for somatic mismatch repair gene defects. However, these tests cannot differentiate somatic (acquired) versus germline alterations, and immunohistochemistry and microsatellite stability assessment can produce false negatives. Finally, the Mayo Muir-Torre syndrome risk score algorithm cannot always reliably determine which patient with a new sebaceous neoplasm should have germline testing. We report three men who presented with a Muir-Torre syndrome-associated sebaceous neoplasm: a 67-year-old male with no personal or family history of cancer who presented with a chest sebaceous carcinoma with MSH2 and MSH6 gene expression loss on immunohistochemistry and a Mayo Muir-Torre syndrome risk score of 0 who declined germline testing; a 74-year-old male with Janus kinase 2 (JAK2)-related myelodysplastic syndrome, yet no history of a Lynch syndrome-associated cancer, who developed a sebaceous epithelioma on his leg with PMS2 gene expression loss by immunohistochemistry and, although Mayo Muir-Torre syndrome risk score was only 1 (suggests no likelihood of a Lynch syndrome germline mismatch repair gene mutation), germline testing demonstrated a PMS2 alteration; and a 59-year-old male with a germline-confirmed MLH1-associated Lynch syndrome and a prior colon carcinoma, who developed a sebaceous adenoma on his nostril that unexpectedly demonstrated preservation of normal MLH1 staining (reflecting a false negative) by immunohistochemistry. In summary, these cases are consistent with the literature suggesting that tumor immunohistochemistry and microsatellite stability testing can miss germline alterations. Hence, we recommend that the initial evaluation of a patient with even a single new Muir-Torre syndrome-associated sebaceous neoplasm should include germline mismatch repair gene mutation testing. Finding a mismatch repair gene germline mutation should prompt genetic counseling, initial and future cancer screening recommendations, and germline testing of family members.

Can the tumor-agnostic evaluation of MSI/MMR status be the common denominator for the immunotherapy treatment of patients with several solid tumors?

Alterations in short-repetitive DNA sequences, known as microsatellite instability (MSI), can reflect deficiencies in Mismatch Repair (MMR) system which represents a major player in DNA integrity maintenance. The incidence of MSI-H/dMMR has been shown to be variable depending on the tumor type. Several studies confirmed that dMMR/MSI status, although less frequent than PD-L1 expression, may better predict response to immune-checkpoint inhibitors (ICIs) in patients with solid tumors. In October 2016, the FDA granted pembrolizumab as breakthrough therapy for the treatment of non-CRC, MSI-H/dMMR tumors, providing, for the first time, a tumor-agnostic indication. In the next future, the tissue-agnostic evaluation of MSI-H/dMMR could become the common denominator for the immunotherapy treatment of patients with different advanced solid tumors, in order to select patient subgroups which may benefit from this therapy. In this Review we provided an overview of the main clinical studies describing the association between MSI-H/dMMR tumors and immunotherapy response.

Detection of MSH2 Gene Methylation in Extramammary Paget's Disease by Methylation-Sensitive High-Resolution Melting Analysis

Background

Extramammary Paget's disease (EMPD) is a rare skin tumor. Hypermethylation in the MSH2 promoter resulting in the downregulation of its protein expression shows a high detection rate in EMPD tumor tissue, which indicates that the methylation of MSH2 may play an important role in the pathogenesis of EMPD.

Objective

This study aims to establish a rapid analysis strategy based on the methylation-sensitive high-resolution melting curve (MS-HRM) to detect the methylation level of the MSH2 promoter.

Methods

With the use of universal methylated human DNA products, we established the MS-HRM standard curve to quantitatively detect the methylation level of the MSH2 promoter. Then, all 57 EMPD tumor DNA samples were analyzed. Pyrosequencing assay was also carried out to test the accuracy and efficacy of MS-HRM. Besides, a total of 54 human normal and other cancerous tissues were included in this study to test the reliability and versatility of the MS-HRM standard curve.

Results

In this study, by using the established MS-HRM, we found that 96.5% (55/57) EMPD tumor samples had varying methylation levels in the MSH2 promoter ranging from 0% to 30%. Then, the methylation data were compared to the results obtained from pyrosequencing, which showed a high correlation between these two techniques by Pearson's correlation (r = 0.9425) and Bland–Altman plots (mean difference = −0.1069) indicating that the methylation levels analyzed by MS-HRM were consistent with DNA pyrosequencing. Furthermore, in 23 normal and 31 other cancerous tissue samples, there were two colorectal cancer (CRC) tissues that tested MSH2 methylation positive (1% and 5%) which confirmed that our established MS-HRM can be widely applied to various types of samples.

Conclusion

MS-HRM standard curve can be used for the detection of the methylation level of MSH2 in EMPD tumor samples and other cancerous tissues potentially, which presents a promising candidate as a quantitative assay to analyze MSH2 promoter methylation in routine pathological procedure.

Immunotherapy for Non-melanoma Skin Cancer

Purpose of Review

The therapeutic landscape for non-melanoma skin cancer (NMSC) has recently expanded with the development of effective and targeted immunotherapy. Here, we provide an overview of the role of immunotherapy in the management of advanced cutaneous carcinomas.

Recent Findings

Several agents were recently U.S. Food and Drug Administration (FDA)-approved for the treatment of locally advanced and metastatic cutaneous squamous cell carcinoma, Merkel cell carcinoma, and basal cell carcinoma. However, recent approvals in tissue-agnostic indications may also benefit other NMSCs including cutaneous adnexal solid tumors with high tumor mutation burdens or microsatellite instability. Furthermore, while FDA-approved indications will likely continue to expand, continued studies are needed to support the role of immunotherapy in the neoadjuvant, adjuvant, and refractory settings.

Summary

Immunotherapy is emerging as the standard of care for several advanced NMSCs not amenable to surgery and radiation. Ongoing evaluation of the clinical trial landscape is needed to optimize enrollment and ensure continued innovation.

Sebaceous Carcinoma Epidemiology and Genetics: Emerging Concepts and Clinical Implications for Screening, Prevention, and Treatment

Sebaceous carcinoma is an aggressive skin cancer with a 5-year overall survival rate of 78% for localized/regional disease and 50% for metastatic disease. The incidence of this cancer has been increasing in the United States for several decades, but the underlying reasons for this increase are unclear. In this article, we review the epidemiology and genetics of sebaceous carcinoma, including recent population data and tumor genomic analyses that provide new insights into underlying tumor biology. We further discuss emerging evidence of a possible viral etiology for this cancer. Finally, we review the clinical implications of recent advances in sebaceous carcinoma research for screening, prevention, and treatment.