Frequency of microsatellite instability in unselected sebaceous gland neoplasias and hyperplasias

Clinical Outcomes in Sebaceous Carcinoma: A Retrospective Two-Center Cohort Study

BACKGROUND

Sebaceous carcinoma (SC) is a rare, potentially recurrent, and life-threatening cutaneous malignancy that can be associated with Muir-Torre syndrome (MTS), a DNA mismatch repair-driven genodermatosis. Earlier studies examining factors associated with recurrence have focused on periocular tumors only.

OBJECTIVE

Examine outcomes of SC and identify factors associated with recurrence.

MATERIALS AND METHODS

Retrospective study from 2 tertiary care centers.

RESULTS

Sixty-seven cases from 63 patients were identified, including 7 cases of MTS and 13 arising in the context of immunosuppression. Fifty-five cases (82.1%) were treated with complete circumferential peripheral and deep margin assessment (CCPDMA) methods. Five recurrences developed during the postoperative period. On univariate analysis, periocular location (odds ratio [OR] 7.6, p = .0410), and lesion size ≥2 cm (OR 9.6, p = .005) were associated with recurrence, whereas CCPDMA (OR 0.052, p = .0006) was inversely associated with recurrence. On multivariate analysis, only lesion size ≥2 cm (OR 9.6, p = .0233) and CCPDMA approaches (OR 0.052, p = .007) were significant.

CONCLUSION

Non-complete circumferential peripheral and deep margin assessment methods and large lesion size were independent risk factors predicting recurrence, whereas anatomic subtype and MTS status were not. These findings can assist in identifying SC cases that may benefit from more aggressive treatment and closer surveillance.

Sebaceous Adenoma: A Dermoscopic Case Perspective

This report focuses on sebaceous skin tumors, specifically sebaceous adenoma, sebaceoma, and sebaceous carcinoma, along with their association with Muir-Torre syndrome (MTS). A clinical case of a 25-year-old male with a suspected sebaceous neoplasm based on dermoscopy appearance is presented. The histopathological examination confirmed the diagnosis and surgical management resulted in successful treatment. The report highlights the importance of considering differential diagnoses and utilizing dermoscopy for accurate evaluation of these rare skin tumors.

Immunotherapy for Nonmelanoma skin cancer: Facts and Hopes

Non-melanoma skin cancer (NMSC) is the most frequently diagnosed malignancy in humans, representing a broad range of cutaneous tumors. Keratinocyte carcinomas, including basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (CSCC), are the most common NMSCs. The incidence of BCC and CSCC are steadily increasing due to a progressively aging population, chronic exposure to ultraviolet radiation, and increased awareness with earlier diagnosis. Rarer NMSCs such as Merkel cell carcinoma (MCC) and cutaneous adnexal carcinomas (CACs) are also on the rise. Although the majority of NMSC tumors are localized at diagnosis and managed effectively with curative surgery and radiation, in rare cases with nodal and distant metastases, systemic therapy is often required. As our understanding of the immunologic characteristics of NMSCs has improved, effective treatment options have expanded with the development of immunotherapy. The U.S. Food and Drug Administration (FDA) recently approved several immune checkpoint inhibitors for the treatment of locally advanced and metastatic MCC, CSCC, and BCC. We review the emerging role of immunotherapy as the standard of care for several advanced NMSCs not amenable to surgery and/or radiation and underscore the need for considering clinical trials of novel strategies in patients when immunotherapy does not provide durable benefit. Finally, we explore the potential of neoadjuvant and adjuvant immunotherapy.

Absence of microsatellite instability in extramammary Paget's disease

Background

Deficiency of DNA mismatch repair (MMR) induces microsatellite instability (MSI). Pembrolizumab, an antibody targeting PD‐1 (an immune checkpoint inhibitor), is more effective against MMR‐deficient tumours than against MMR‐proficient tumours. The status of MMR is a useful biomarker for predicting the effectiveness of pembrolizumab administration. Although the status of MMR has attracted attention in skin tumours, there are few reports on MSI in extramammary Paget's disease (EMPD).

Objectives

To evaluate the status of MMR in patients with EMPD.

Materials & Methods

One hundred one patients with EMPD were included. MMR status of the genomic DNA of each subject was analysed using Promega panel (approved as a companion diagnostic agent for the administration of pembrolizumab).

Results

MSI testing showed the occurrence rates of MSI‐high (more than two markers are unstable), MSI‐low (one marker is unstable) and MSS (all markers are stable) tumour tissues were 0% (0/101), 1.0% (1/101) and 99.0% (100/101), respectively.

Conclusion

The status of MMR may not be useful for the potential therapeutic application of pembrolizumab.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

Clinical Pan-Cancer Assessment of Mismatch Repair Deficiency Using Tumor-Only, Targeted Next-Generation Sequencing

PURPOSE

Given regulatory approval of immune checkpoint inhibitors in patients with mismatch repair-deficient (MMR-D) cancers agnostic to tumor type, it has become important to characterize occurrence of MMR-D and develop cost-effective screening approaches. Using a next-generation sequencing (NGS) panel (OncoPanel), we developed an algorithm to identify MMR-D frequency in tumor samples and applied it in a clinical setting with pathologist review.

METHODS

To predict MMR-D, we adapted methods described previously for use in NGS panels, which assess patterns of single base-pair insertion or deletion events occurring in homopolymer regions. Tumors assayed with OncoPanel between July 2013 and July 2018 were included. For tumors tested after June 2017, sequencing results were presented to pathologists in real time for clinical MMR determination, in the context of tumor mutation burden, other mutational signatures, and clinical data.

RESULTS

Of 20,301 tumors sequenced, 2.7% (553) were retrospectively classified as MMR-D by the algorithm. Of 4,404 samples with pathologist sign-out of MMR status, the algorithm classified 147 (3.3%) as MMR-D: in 116 cases, MMR-D was confirmed by a pathologist, five cases were overruled by the pathologist, and 26 were assessed as indeterminate. Overall, the highest frequencies of OncoPanel-inferred MMR-D were in endometrial (21%; 152/723), colorectal (9.7%; 169/1,744), and small bowel (9.3%; 9/97) cancers. When algorithm predictions were compared with historical MMR immunohistochemistry or polymerase chain reaction results in a set of 325 tumors sequenced before initiation of pathologist assessment, the overall sensitivity and specificity of the algorithm were 91.1% and 98.2%, respectively.

CONCLUSION

We show that targeted, tumor-only NGS can be leveraged to determine MMR signatures across tumor types, suggesting that broader biomarker screening approaches may have clinical value.

Muir-Torre syndrome: sebaceous carcinoma concurrent with colon cancer in a kidney transplant recipient; a case report

BACKGROUND

Sebaceous carcinoma is a rare but progressive malignant skin cancer, and the incidence is approximately five times higher in post-transplant patients than in people who have not received kidney transplants. Sebaceous carcinoma is sometimes found concurrently with visceral cancers and a genetic abnormality, Muir-Torre syndrome. We report the case of a female kidney transplant recipient with sebaceous carcinoma concurrent with colon cancer 10 years after transplantation.

CASE PRESENTATION

A 43-year-old woman was admitted due to a rapidly progressive tumor on her head. Histologically, the tumor was diagnosed as sebaceous carcinoma. We diagnosed her with Muir-Torre syndrome based on the following evidence: 1) high prevalence of microsatellite instability in gene locus assay, 2) absence of mismatch repair proteins in the sebaceous carcinoma on immunohistochemical analysis, and 3) a genetic mutation of 1226_1227delAG in the MSH2 exon 7 in the lesion detected by DNA sequencing analysis. Several reports have shown an association between immunosuppressive agents and latent Muir-Torre syndrome progression. Therefore, the progression of colon cancer in this case originated from her genetic mutation for Muir-Torre syndrome and long-term use of immunosuppressive agents.

CONCLUSION

This case report not only highlights the importance of adequate diagnosis and therapy for Muir-Torre syndrome, but also suggests the further prevention of the development of malignant tumors in kidney transplant recipients. Physicians should be mindful that sebaceous carcinoma in kidney transplant recipients is highly concurrent with Muir-Torre syndrome.

Clinico‐pathological predictors of mismatch repair deficiency in sebaceous neoplasia: A large case series from a single Australian private pathology service

Background/Objectives

Loss of expression of mismatch repair (MMR) proteins is frequently observed in sebaceous skin lesions and can be a herald for Lynch syndrome. The aim of this study was to identify clinico‐pathological predictors of MMR deficiency in sebaceous neoplasia that could aid dermatologists and pathologists in determining which sebaceous lesions should undergo MMR immunohistochemistry (IHC).

Methods

An audit of sebaceous skin lesions (excluding hyperplasia) where pathologist‐initiated MMR IHC was performed between January 2009 to December 2016 was undertaken from a single pathology practice identifying 928 lesions from 882 individuals. Lesions were further analysed for differences in gender, age at diagnosis, lesion type and anatomic location, stratified by MMR status.

Results

The 882 individuals (67.7% male) had a mean (SD) age of diagnosis of 68.4 ± 13.3 years. Nearly two‐thirds of the lesions were sebaceous adenomas, with 82.6% of all lesions occurring on the head and neck. MMR deficiency, observed in 282 of the 919 lesions (30.7%), was most common in sebaceous adenomas (210/282; 74.5%). MMR‐deficient lesions occurred predominantly on the trunk or limbs (64.7%), compared with 23.2% in head or neck (P < 0.001). Loss of MSH2 and MSH6 protein expression was most frequent pattern of loss (187/281; 66.5%). The highest AUC for discriminating MMR‐deficient sebaceous lesions from MMR‐proficient lesions was observed for the ROC curve based on subgroups defined by type and anatomic location of the sebaceous lesion (AUC = 0.68).

Conclusion

The best combination of measured clinico‐pathological features achieved only modest positive predictive values, sensitivity and specificity for identifying MMR‐deficient sebaceous skin lesions.

Mutant Lef1 controls Gata6 in sebaceous gland development and cancer

Mutations in Lef1 occur in human and mouse sebaceous gland (SG) tumors, but their contribution to carcinogenesis remains unclear. Since Gata6 controls lineage identity in SG, we investigated the link between these two transcription factors. Here, we show that Gata6 is a β‐catenin‐independent transcriptional target of mutant Lef1. During epidermal development, Gata6 is expressed in a subset of Sox9‐positive Lef1‐negative hair follicle progenitors that give rise to the upper SG. Overexpression of Gata6 by in utero lentiviral injection is sufficient to induce ectopic sebaceous gland elements. In mice overexpressing mutant Lef1, Gata6 ablation increases the total number of skin tumors yet decreases the proportion of SG tumors. The increased tumor burden correlates with impaired DNA mismatch repair and decreased expression of Mlh1 and Msh2 genes, defects frequently observed in human sebaceous neoplasia. Gata6 specifically marks human SG tumors and also defines tumors with elements of sebaceous differentiation, including a subset of basal cell carcinomas. Our findings reveal that Gata6 controls sebaceous gland development and cancer.

Microsatellite instability in gastric cancer: molecular bases, clinical perspectives, and new treatment approaches

Gastric cancer is one of the most aggressive malignancies, with limited treatment options in both locally advanced and metastatic setting, resulting in poor prognosis. Based on genomic characterization, stomach tumour has recently been described as a heterogeneous disease composed by different subtypes, each of them with peculiar molecular aspects and specific clinical behaviour. With an incidence of 22% among all western gastric tumour cases, stomach cancer with microsatellite instability was identified as one of these subgroups. Retrospective studies and limited prospective trials reported differences between gastric cancers with microsatellite stability and those with instability, mainly concerning clinical and pathological features, but also in regard to immunological microenvironment, correlation with prognostic value, and responses to treatment. In particular, gastric cancer with microsatellite instability constitutes a small but relevant subgroup associated with older age, female sex, distal stomach location, and lower number of lymph-node metastases. Emerging data attribute to microsatellite instability status a favourable prognostic meaning, whereas the poor outcomes reported after perioperative chemotherapy administration suggest a detrimental role of cytotoxic drugs in this gastric cancer subgroup. The strong immunogenicity and the widespread expression of immune-checkpoint ligands make microsatellite instability subtype more vulnerable to immunotherapeutic approach, e.g., with anti-PD-L1 and anti-CTLA4 antibodies. Since gastric cancer with microsatellite instability shows specific features and clinical behaviour not overlapping with microsatellite stable disease, microsatellite instability test might be suitable for inclusion in a diagnostic setting for all tumour stages to guarantee the most targeted and effective treatment to every patient.

Microsatellite Instability: A Predictive Biomarker for Cancer Immunotherapy

Immunotherapy has shown promising results in various types of cancers. Checkpoint inhibitor drugs developed for cancer immunotherapy have been approved by the US Food and Drug Administration (FDA) for patients with advanced melanoma, non-small cell lung cancer, renal cell carcinoma, bladder cancers, and refractory Hodgkin lymphoma. In the latest announcement, the FDA has granted accelerated approval to pembrolizumab for pediatric and adult patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient solid tumors. This is the first time the agency has approved a cancer treatment based on a common biomarker rather than organ-based approach. MSI-H, either due to inherited germline mutations of mismatch repair genes or epigenetic inactivation of these genes, is found in a subset of colorectal and noncolorectal carcinomas. It is known that MSI-H causes a build up of somatic mutations in tumor cells and leads to a spectrum of molecular and biological changes including high tumor mutational burden, increased expression of neoantigens and abundant tumor-infiltrating lymphocytes. These changes have been linked to increased sensitivity to checkpoint inhibitor drugs. In this mini review, we provide an update on MSI-related solid tumors with special focus on the predictive role of MSI for checkpoint immunotherapy.

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.

Microsatellite Instability as a Biomarker for PD-1 Blockade

Initial results by Le and colleagues, which were published in the June 25, 2015 issue of the New England Journal of Medicine, report significant responses of cancers with microsatellite instability (MSI) to anti-PD-1 inhibitors in patients who failed conventional therapy. This finding fits into a broader body of research associating somatic hypermutation and neoepitope formation with response to immunotherapy, with the added benefit of relying on a simple, widely used diagnostic test. This review surveys the pathogenesis and prognostic value of MSI, diagnostic guidelines for detecting it, and the frequency of MSI across tumors, with the goal of providing a reference for its use as a biomarker for PD-1 blockade. MSI usually arises from either germline mutations in components of the mismatch repair (MMR) machinery (MSH2, MSH6, MLH1, PMS2) in patients with Lynch syndrome or somatic hypermethylation of the MLH1 promoter. The result is a cancer with a 10- to 100-fold increase in mutations, associated in the colon with poor differentiation, an intense lymphocytic infiltrate, and a superior prognosis. Diagnostic approaches have evolved since the early 1990s, from relying exclusively on clinical criteria to incorporating pathologic features, PCR-based MSI testing, and immunohistochemistry for loss of MMR component expression. Tumor types can be grouped into categories based on the frequency of MSI, from colorectal (20%) and endometrial (22%-33%) to cervical (8%) and esophageal (7%) to skin and breast cancers (0%-2%). If initial results are validated, MSI testing could have an expanded role as a tool in the armamentarium of precision medicine.

Parotid Sebaceous Carcinoma in Patient with Muir Torre Syndrome, Caused by MSH2 Mutation

Sebaceous carcinoma of parotid gland are extremely rare with only 29 cases reported so far. The development of parotid sebaceous carcinoma in association with mutation in the mismatch repair gene that causes Muir Torre Syndrome (MTS), a subset of Lynch Syndrome, is still unclear. This study describes such a case and reviews the literature to see if an association between parotid sebaceous carcinoma and multiple visceral malignancies seen in Lynch Syndrome has ever been described. MTS represents a small subset of the Hereditary Non Polyposis Colorectal Carcinoma family, thought to be a subtype of Lynch Syndrome, where patients are prone to develop multiple visceral cancers involving gastrointestinal and genitourinary tract along with sebaceous and non-sebaceous tumours of the skin. MTS is a rare hereditary, autosomal dominant cancer syndrome caused by Microsatellite Instability and defect in DNA mismatch repair protein. The germline mutation involves mostly hMSH2 and hMLH1 genes. In MTS the skin of the head and neck area with the periocular region in particular, is affected but sebaceous carcinomas of the parotid associated with visceral malignancies has not yet been reported in literature. Here we report an index case of sebaceous carcinoma of parotid gland in a patient with MTS.

Defective DNA mismatch repair activity is common in sebaceous neoplasms, and may be an ineffective approach to screen for Lynch syndrome

A subset of individuals with Lynch syndrome (LS) has a variant called Muir-Torre syndrome (MTS) where patients develop multiple sebaceous neoplasms. Absence of gene expression and microsatellite instability (MSI) have been welldocumented in LS neoplasms. It is unclear whether the presence of these abnormalities in isolated sebaceous neoplasms would indicate the likely presence of otherwise unsuspected LS or MTS. 164 specimens of sporadic cutaneous sebaceous neoplasms were obtained. IHC was performed for expression of the DNA mismatch repair (MMR) genes MSH2 and MLH1. A 5-marker mononucleotide repeat microsatellite panel was analyzed to detect MSI, and two or more mutated markers were required for MSI. 164 sebaceous neoplasms were obtained from 162 patients. IHC data was successfully obtained from 162 samples and MSI data was obtained from 138 samples. 50/162 (31%) had abnormal IHC with loss of staining for either MSH2 (37/162, 23%), MLH1 (9/162, 5%) or both (4/162, 2%). 37% (52/138) of the tumors had MSI. 82% (111/136) of those with both IHC and MSI results correlated as expected. 18% (25/136) showed discordance between IHC and MSI. 69/163 (42%) had either abnormal IHC or MSI, indicating deficient DNA MMR activity. Given the substantial proportion of DNA MMR deficiency in these sebaceous neoplasms, screening for DNA MMR defects in sebaceous neoplasms would not appear to be an effective way to distinguish patients with LS or MTS from those with sporadic skin lesions and an ordinary risk of cancer.

Mismatch Repair Protein Expression in Fordyce Granules

Fordyce spots are a frequent condition under which sebaceous glands are found in the oral mucosa. There are 2 studies in the literature that have found an association between Fordyce spots and either Muir-Torre syndrome or Lynch syndrome. Despite this, no study on the expression of mismatch repair (MMR) proteins has been performed on biopsies of Fordyce granules. In this study, we intend to study the expression of MMR proteins under Fordyce condition. We investigated 9 cases of Fordyce spots of the oral mucosa from 6 men and 3 women, using immunohistochemistry with antibodies for the MutS protein homolog 6 (MSH6), MutS protein homolog 2 (MSH2), MutL protein homolog 1 (MLH1), and postmeiotic segregation increased 2 (PMS2). All cases showed the preservation of the expression of all markers. Even though a strong association has been demonstrated between Lynch syndrome and Fordyce spots, our study suggests that studying the biopsies of Fordyce condition by immunohistochemistry for MMR proteins might not be necessary.

Family with MSH2 mutation presenting with keratoacanthoma and precancerous skin lesions

Muir-Torre syndrome (MTS) is a familial cancer syndrome characterized by a predisposition to keratoacanthoma (KA) and sebaceous tumors. Although MTS and hereditary non-polyposis colorectal cancer (HNPCC) share the same genetic alterations in mismatch repair (MMR) genes, the other skin lesions in MTS or HNPCC have been only rarely reported. We report a family with an MSH2 mutation c.1126_1127delTT (p.Leu376Thrfs*12). A 46-year-old male proband developed KA with sebaceous differentiation, colon cancer and gastric cancer, and fulfilled the diagnostic criteria for MTS. His 80-year-old mother, diagnosed with HNPCC, presented with multiple gastrointestinal tract cancers, Bowen's disease and actinic keratosis. Immunostaining revealed attenuated MSH2 protein expression in KA, as well as in Bowen's disease and actinic keratosis lesions. These findings suggest that MMR gene abnormality is also critical in the development of benign or malignant cutaneous tumors such as actinic keratosis and Bowen's disease in MTS/HNPCC patients.

Sebaceous neoplasms and the immunoprofile of mismatch-repair proteins as a screening target for syndromic cases

INTRODUCTION

Muir-Torre syndrome (MTS), a subset of Lynch syndrome, is characterized by concurrent or sequential development of sebaceous neoplasms, and internal malignancies, specifically colorectal carcinoma (CRC), and can be related to mismatch-repair (MMR)-protein deficiency. In CRC context, p16-negativity in MLH1-deficient cases may denote methylation rather than mutation. The prime aim of this study was to evaluate the mismatch-repair (MMR)-protein deficiency and the p16 status among sebaceous neoplasms.

MATERIAL AND METHOD

From January 1990 through October 2012, 26 sebaceous adenomas (SAs) and 6 sebaceous carcinomas (SCs) were accrued. The expression of MLH1, MSH2, MSH6, and PMS2 was recorded. MLH1-deficient cases were tested for p16 status.

RESULTS

Eighteen (56%) of the 32 specimens with SA or SC displayed MMR-protein deficiency, comprising 17 (65.4%) SAs (MSH2/MSH6 loss in 12, MLH1/PMS2 loss in 3, MSH6 loss only in 2 cases) and 1 (16.7%) SC (MLH1/PMS2 loss). All 4 MLH1 deficient cases were p16-positive.

CONCLUSION

A substantial proportion of sebaceous neoplasms were MMR-protein deficient and thus likely MTS candidates. Given the low prevalence of sebaceous neoplasms in Denmark, immunohistochemistry for the four MMR-proteins is recommended in the initial diagnostic approach. The addition of p16 was none-informative, but evaluation of its utility in larger series is warranted.

Lynch syndrome-associated neoplasms: a discussion on histopathology and immunohistochemistry

It was a century ago that Warthin, a pathologist, first described the clinical condition now known as Lynch syndrome. One hundred years later, our understanding of this syndrome has advanced significantly. Much of the progress took place over the last 25 years and was marked by a series of interacting developments from the disciplines of clinical oncology, pathology, and molecular genetics, with each development serving to guide or enhance the next. The advancement of our understanding about the pathology of Lynch syndrome associated tumors exemplifies such intimate interplay among disciplines. Today, accumulative knowledge has enabled surgical pathologists to detect tumors that are likely to be associated with Lynch syndrome, and the pathologist is playing an increasingly more important role in the care of these patients. The pathologist's ability is afforded primarily by information gained from tumor histopathology and by DNA mismatch repair protein immunohistochemistry. It is therefore pertinent both for the pathologists to accurately ascertain this morphologic information, and for all that are involved in the care of these patients to thoroughly understand the implications of such information. This article provides an overview of the development of histopathology and immunohistochemistry in Lynch syndrome-associated tumors, particularly in colorectal and endometrial cancers, and outlines the issues and current status of these specific pathologic aspects in not only the major tumors but also those less commonly seen or only newly reported in Lynch syndrome patients.

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

PURPOSE

To characterize mismatch repair protein expression and the role of DNA repair abnormalities in sebaceous carcinomas of the ocular adnexa.

DESIGN

Retrospective case-series study.

METHODS

We reviewed 10 cases of sporadic sebaceous carcinoma and 1 case involving a patient with a family history consistent with Muir-Torre syndrome. Immunohistochemistry was used to analyze the presence of 4 mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) in these tumors. DNA was extracted from 7 of the larger tumors as well as from adjacent normal control tissue and microsatellite instability (MSI) analysis using 5 highly sensitive mononucleotides and 2 pentanucleotides was performed.

RESULTS

All 10 sporadic periocular sebaceous carcinomas maintained strong staining of the 4 mismatch repair genes, while tumor from the patient with Muir-Torre syndrome showed loss of staining for the mismatch repair genes MSH2 and MSH6. MSI testing of 7 tumors identified no changes in sporadic cases and yielded results supporting presence of repeat sequence instability in the Muir-Torre-associated case.

CONCLUSIONS

Sporadic sebaceous carcinoma of the ocular adnexa is not commonly associated with a loss of mismatch repair genes or microsatellite instability.

Mismatch repair protein deficiency is common in sebaceous neoplasms and suggests the importance of screening for Lynch syndrome

The association between Lynch syndrome and sebaceous neoplasms is well characterized. The absence of expression of mismatch repair proteins (MMRPs) by immunohistochemistry (IHC) is often used in other Lynch-associated tumors to guide testing. IHC for MLH1, PMS2, MSH2, and MSH6 was performed on 36 benign and malignant sebaceous neoplasms with the absence of one or more MMRP in 38.9% of cases. Among lesions with abnormal IHC, 71.4% were missing both MSH2 and MSH6, 21.4% lacked MLH1 and PMS2, and 7.1% lacked only MSH6. Of the 10 patients with absent MMRP, 5 had gene-test confirmed Lynch syndrome, 3 had no suggestive personal or family medical history and 2 had no recorded data. Tumor-infiltrating lymphocytes in neoplasms with absent MMRP were statistically significantly greater than in those with intact MMRP (16.5 vs. 9.7, P = 0.027). MMRP deficiency is common in sebaceous neoplasms, suggesting the importance of screening for Lynch syndrome in these patients.

10 rare tumors that warrant a genetics referral

The number of described cancer susceptibility syndromes continues to grow, as does our knowledge on how to manage these syndromes with the aim of early detection and cancer prevention. Oncologists now have greater responsibility to recognize patterns of cancer that warrant referral for a genetics consultation. While some patterns of common cancers are easy to recognize as related to hereditary cancer syndromes, there are a number of rare tumors that are highly associated with cancer syndromes yet are often overlooked given their infrequency. We present a review of ten rare tumors that are strongly associated with hereditary cancer predisposition syndromes: adrenocortical carcinoma, carcinoid tumors, diffuse gastric cancer, fallopian tube/primary peritoneal cancer, leiomyosarcoma, medullary thyroid cancer, paraganglioma/pheochromocytoma, renal cell carcinoma of chromophobe, hybrid oncocytoic, or oncocytoma histology, sebaceous carcinoma, and sex cord tumors with annular tubules. This review will serve as a guide for oncologists to assist in the recognition of rare tumors that warrant referral for a genetic consultation.

Dermatology clinics: what's new in dermatopathology: news in nonmelanocytic neoplasia

This article reviews the recent dermatopathology literature involving nonmelanocytic neoplasia, with a focus on important work done over the last 5 years. The discussion includes advances in the understanding of Merkel cell carcinoma pathogenesis and prognosis; changes in the seventh edition of the American Joint Committee of Cancer staging manual in reference to staging of squamous cell carcinoma and Merkel cell carcinoma; newly described or rare histopathologic patterns and entities including squamoid eccrine ductal carcinoma, rippled-pattern adnexal neoplasms, onychomatricoma, spindle cell predominant trichodiscoma/neurofollicular hamartoma, and myoepithelioma; and microsatellite instability in sebaceous neoplasms of Muir-Torre syndrome and other tumors.

Areolar sebaceous hyperplasia with underlying primary duct carcinoma of the breast in a woman with Donohue syndrome (leprechaunism)

Areolar hyperplasia is only reported when exaggerated, and even so, exaggerated areolar sebaceous hyperplasia is rare. We have recently seen a case of areolar sebaceous hyperplasia in a 32-year-old woman with Donohue syndrome (leprechaunism), who also had an invasive ductal carcinoma in the same breast. The patient showed typical "elfin-like" face with wide nostrils and thick lips, large and low-set ears, and dysplastic nails. The areola showed a yellowish thickened plaque of 5-cm diameter that corresponded to a hyperplasia of the sebaceous glands. Immunohistochemistry for the mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) was performed on the sebaceous hyperplasia and on the breast carcinoma, and no lack of expression of the markers was evidenced. We have found no other reported case of areolar sebaceous hyperplasia either in cases of breast carcinoma or in cases of leprechaunism.

A two-antibody mismatch repair protein immunohistochemistry screening approach for colorectal carcinomas, skin sebaceous tumors, and gynecologic tract carcinomas

Mismatch repair protein immunohistochemistry is a widely used method for detecting patients at risk for Lynch syndrome. Recent data suggest that a two-antibody panel approach using PMS2 and MSH6 is an effective screening protocol for colorectal carcinoma, but there are limited data concerning this approach for extraintestinal tumors. The purpose of this study was to review the utility of a two-antibody panel approach in colorectal carcinoma and extraintestinal tumors. We evaluated mismatch repair protein expression in two cohorts: (1) a retrospective analysis of intestinal and extraintestinal tumors (n=334) tested for mismatch repair protein immunohistochemistry and (2) a prospectively accrued series of intestinal, gynecologic tract, and skin sebaceous neoplasms (n=98). A total of 432 cases were analyzed, including 323 colorectal, 50 gynecologic tract, 49 skin sebaceous, and 10 other neoplasms. Overall, 102/432 tumors (24%) demonstrated loss of at least one mismatch repair protein. Concurrent loss of MLH1 and PMS2 was the most common pattern of abnormal expression (50/432, 12%) followed by concurrent loss of MSH2 and MSH6 (33/432, 8%). Of 55 cases with abnormal PMS2 expression, 5 (9%) demonstrated isolated loss of PMS2 expression. Of 47 cases with abnormal MSH6 expression, 14 (30%) demonstrated isolated loss of MSH6 expression. Isolated loss of MLH1 or MSH2 was not observed. Colorectal carcinomas more frequently demonstrated abnormal expression of PMS2 (39/59, 66%). Skin sebaceous neoplasms more frequently demonstrated abnormal expression of MSH6 (18/24, 75%, respectively). A total of 65 tumors with abnormal mismatch repair protein expression were tested for microsatellite instability (MSI): 47 (72%) MSI high, 9 (14%) MSI low, and 9 (14%) microsatellite stable (MSS). Abnormal MSH6 expression accounted for 14/18 (78%) cases that were MSS or MSI low. Our findings confirm the utility of a two-antibody approach using PMS2 and MSH6 in colorectal carcinoma and indicate that this approach is effective in extraintestinal neoplasms associated with Lynch syndrome.

Immunosuppression and sebaceous tumors: a confirmed diagnosis of Muir-Torre syndrome unmasked by immunosuppressive therapy

Muir-Torre syndrome (MTS) is an autosomal dominant genodermatosis caused by mutations in the DNA mismatch repair genes MLH1 and MSH2. This case describes a patient with an extensive family history of colon cancer who experienced the onset of multiple sebaceous adenomas and carcinomas after undergoing kidney transplantation and receiving immunosuppressive therapy. The finding of deficient MSH2 expression in the immunohistochemical analysis of a sebaceous carcinoma prompted genetic testing for a systemic mutation in the mismatch repair gene. A systemic mutation of the MSH2 gene was detected and, despite the absence of a visceral malignancy, the diagnosis of MTS was made. Immunosuppression has previously been thought to play a possible role in unmasking a latent MTS phenotype in transplant recipients, but systemic mutations have not previously been analyzed. The relationship between immunosuppression and sebaceous tumors with the possibility of unmasking a MTS phenotype in transplant recipients is discussed.

Muir-Torre syndrome: Facts and controversies

The cutaneous presentation of a tumor sometimes has implications for a patient and his or her family, and Muir-Torre syndrome is an example of this. Because a single skin lesion can have broad consequences, it is important for clinicians to be aware of Muir-Torre syndrome. The definition, potential clues, the role of ancillary testing (microsatellite, immunohistochemical, and genetic), and screening recommendations are reviewed.

Sebaceous lesions and their associated syndromes: part II

Sebaceous lesions are associated with two syndromes with widespread multisystem disorders and tumors. Linear sebaceous nevus syndrome has been traditionally known as the triad of sebaceous nevus of Jadassohn, seizures, and mental retardation. This syndrome encompasses a much broader spectrum of multisystem disorders, which is explored below. Muir-Torre syndrome is described as the presence of sebaceous tumors or keratoacanthomas with an underlying visceral malignancy. It is caused by mutations in DNA mismatch repair genes. We discuss its relationship with Lynch syndrome and suggest a comprehensive algorithm on how to screen patients with sebaceous neoplasms for Muire-Torre syndrome. We also provide suggested intensive cancer screening guidelines based on recommendations for patients with Lynch syndrome that may also be of value for patients with Muir-Torre syndrome.

Cutaneous sebaceous neoplasms as markers of Muir-Torre syndrome: a diagnostic algorithm

Sebaceous gland neoplasms such as adenoma, epithelioma, and carcinoma are uncommon cutaneous tumors. Although sporadic, their occurrence is clinically significant because of their association with Muir-Torre syndrome (MTS). MTS is a rare autosomal dominant genodermatosis characterized by the occurrence of sebaceous gland neoplasms and/or keratoacanthomas associated with visceral malignancies that include gastrointestinal and genitourinary cancers. MTS is usually the result of germline mutation in one or more of the DNA mismatch repair (MMR) genes. MMR genes commonly implicated include MSH-2 and MLH-1 and, more recently, MSH-6. Recent evidence suggests that immunohistochemistry is very sensitive and effective in detecting these defects in cutaneous tumors in MTS. In addition, the genetic instability of cutaneous and visceral tumors in MTS caused by the defects in MMR genes can also be detected, using polymerase chain reaction (PCR)-based techniques, for microsatellite instability (MSI). Given that some sebaceous neoplasms represent cutaneous markers of MTS, what should we as dermatopathologists be advocating? Should we be looking for absence/loss of MMRs in all sebaceous neoplasms? When should we recommend assaying for MSI? This review attempts to address all of these issues with a view to streamlining the work-up of a patient presenting for the first time with a sebaceous neoplasm and no prior personal or family history of internal malignancies.

Incidence of cutaneous sebaceous carcinoma and risk of associated neoplasms: insight into Muir-Torre syndrome

BACKGROUND

Sebaceous tumors of the skin occurring in association with an internal malignancy characterize Muir-Torre syndrome (MTS), a variant of hereditary nonpolyposis colon cancer (Lynch syndrome). To the authors' knowledge, only limited information exists regarding incidence patterns of sebaceous carcinoma (SC), and no prior study has quantified risks of associated cancers.

METHODS

The authors calculated cutaneous SC incidence rates (IRs) and IR ratios in 9 US Surveillance, Epidemiology, and End Results program registries (1973-2003). Indirectly standardized incidence ratios and 95% confidence intervals (95% CIs) were calculated for subsequent cancers among 2-month survivors of SC and for subsequent SC after other primary cancers.

RESULTS

Among 664 cases of cutaneous SC, nearly 90% were diagnosed among whites (IR, 0.11 per 100,000 person-years), with significantly lower IR noted among blacks (IR, 0.04). Whereas eyelid SC IRs demonstrated no sex differences and stabilized in recent years, IRs of noneyelid SC predominated in men and rose steadily over time. Survivors of SC had a 43% (95% CI, 15%-76%) increased risk of subsequent cancer, and risk of SC was elevated by 52% (95% CI, 24%-84%) among survivors of other cancers. Whether before or after SC, the significant excesses of other primary cancers were limited to noneyelid SC. Patterns suggestive of genetic predisposition included >20-fold risks for early-onset (diagnosed in patients aged <50 years) SC associated with colon, pancreatic, ovarian, or uterine corpus cancers, whereas late-onset SC (diagnosed in patients aged > or =50 years) predisposed to ureter cancer.

CONCLUSIONS

This population-based study of cutaneous SC revealed an association with a spectrum of early-onset cancers consistent with MTS. Etiologic heterogeneity was suggested by differences between eyelid and noneyelid SC in incidence patterns and associated cancer risks.

Deletions of BRCA1/2 and p53 R248W gain-of-function mutation suggest impaired homologous recombination repair in fragile histidine triad-negative sebaceous gland carcinomas

BACKGROUND

Sebaceous gland carcinomas represent rare malignancies of the skin and some 60% of them demonstrate high-grade microsatellite instability on the background of a defective mismatch repair system. However, a significant fraction of periocular sebaceous gland carcinomas exhibits microsatellite stability associated with a frequent loss of the candidate tumour suppressor fragile histidine triad (FHIT).

OBJECTIVES

We hypothesized that in those sebaceous gland carcinomas with microsatellite stability and loss of FHIT, effector molecules participating in homologous recombination repair (HRR), such as BRCA1/2, could be somatically inactivated.

METHODS

A pilot series of 10 paraffin-embedded sebaceous gland carcinoma specimens with a defined FHIT status was studied for loss of heterozygosity (LOH) events in the genes BRCA1, BRCA2, FHIT and WWOX. We sequenced the coding exons 5-8 of the p53 gene.

RESULTS

Sebaceous gland carcinomas with FHIT negativity displayed LOH and biallelic deletions of the BRCA1 gene in five of 10 (50%) of the sebaceous gland carcinoma specimens analysed. Tumour-specific genomic losses close to BRCA2 were also uncovered. A homozygous p53 R248W gain-of-function mutation as the result of a CGG to TGG transition was identified in one of seven sebaceous gland carcinomas. It has been demonstrated previously that p53 R248W mutants inactivate ATM-directed HRR. This particular sebaceous gland carcinoma presented with concomitant genomic deletions at the BRCA1 and BRCA2 loci, and also at the constitutively fragile sites FRA3B/FHIT and FRA16D/WWOX.

CONCLUSIONS

Our study demonstrates for the first time that microsatellite-stable FHIT-negative sebaceous gland carcinomas accumulate mutations that target central components of the HRR network. This observation will prompt investigations in synthetic lethality of BRCA-deficient sebaceous gland carcinomas by therapeutic poly(ADP-ribose) polymerase inhibitors.

MSH-6: extending the reliability of immunohistochemistry as a screening tool in Muir-Torre syndrome

The subtype of Muir-Torre syndrome, allelic to hereditary nonpolyposis colorectal cancer is typically associated with germline mutations in the mismatch repair proteins MSH-2 and/or MLH-1. More recently, mutation in an additional mismatch repair protein MSH-6 has been documented in a patient with Muir-Torre syndrome. Given this, the aim of the present study was to ascertain the frequency of the same in unselected sebaceous gland neoplasms. Overall, we found that 59% of sebaceous neoplasms exhibited a mutation in at least one mismatch repair protein gene -- a prevalence rate similar to that reported previously by others. Of interest, we found MSH-6 to be the mismatch repair protein most commonly lost 17/41 (41%), followed by MSH-2 14/41 (34%) and MLH-18/41 (20%) and the positive predictive value of each were as follows: MLH-1 88%, MSH-6 67% and MSH-2 55%. The frequency of a MSH-6 germline mutation in our cohort indicates that it is not a rare finding. Evidence indicating microsatellite stability in three of 17 patients with a clinical history indicative of Muir-Torre syndrome and a mutation in only MSH-6 suggests that the phenotype of a germline MSH-6 mutation differs from that of MLH-1 and MSH-2 mutations and further supports the use of immunohistochemistry as a screening tool in patients with Muir-Torre syndrome with an extended panel that includes MSH-6.

Muir-Torre syndrome caused by partial duplication of MSH2 gene by Alu-mediated nonhomologous recombination

We describe a 54-year-old man with a pedicled tumour on the neck. The surgical specimen revealed a sebaceous carcinoma. He belonged to a cancer-prone family susceptible to gastrointestinal cancer. Systemic evaluation for latent malignancies revealed early-stage colonic adenocarcinoma. These findings were compatible with Muir-Torre syndrome (MTS). Microsatellite instability was detected in the sebaceous carcinoma, suggesting a DNA mismatch repair gene mutation. Moreover, duplication of exon 7 generated a nonsense codon at codon 427 of the MSH2 gene causing truncation of MSH2 protein. Immunohistochemical analysis showed diminished MSH2 protein levels in the sebaceous carcinoma and colonic adenocarcinoma. To date, there have been no reports showing duplication of exon 7 of the MSH2 gene in MTS or hereditary nonpolyposis colorectal cancer kindreds. Furthermore, the present case indicates that the dermatologist plays an important role in the diagnosis of MTS and evaluation for latent malignancies.

Mismatch Repair Proteins Expression and Microsatellite Instability in Skin Lesions With Sebaceous Differentiation: A Study in Different Clinical Subgroups With and Without Extracutaneous Cancer

Muir-Torre syndrome (MTS) is defined as the association of a sebaceous tumor or keratoacanthoma and an extracutaneous neoplasm, mainly from the gastrointestinal or genitourinary tracts. MTS is related to hereditary non-polyposis colorectal cancer (HNPCC), a syndrome with germline mutations in the mismatch repair (MMR) gene(s), leading to microsatellite instability (MSI). In this study, using immunohistochemistry and a microsatellite instability assay, we analyzed the incidence of MMR gene abnormalities in 79 sebaceous lesions from 70 patients, 26 of whom also had an extracutaneous visceral neoplasm. We were unable to investigate the family histories of our patients regarding other tumors in order to assess which of our cases met the Amsterdam criteria. Defective MMR protein expression (MMR-) was found in 18/70 (25.7%) patients, with an identical distribution between those having an isolated skin tumor (11/44, 25.0%) and those with an extracutaneous cancer (7/26, 25.4%). In the sporadic group, MMR negative lesions were significantly more frequent in extrafacial areas (P = 0.03). High concordance was found between MMR expression in sebaceous lesions and the extracutaneous neoplasm in the same patient (20/23, 86.9%), as well as between MMR expression and microsatellite status (18/20, 90%). In conclusion, this study confirms the value of immunohistochemistry to identify MMR defective tumors. However, since only a minority of sebaceous neoplasms in patients who also have an extracutaneous cancer display MMR defects, these techniques are of limited value for the identification of "clinically defined" MTS.

BRAF Mutations in Multiple Sebaceous Hyperplasias of Patients Belonging to MYH-Associated Polyposis Pedigrees

The characteristics of sebaceous gland hyperplasia (SGH) consist of yellowish or skin-colored papules and nodules. Chronic sun exposure and immunosuppressed conditions are the main environmental risk factors, whereas chronological aging regulated by hormones and molecular changes are the intrinsic risk factors. We have evaluated the contribution of BRAF, K-Ras, and N-Ras mutations to the pathogenesis of SGHs in four patients belonging to three MYH-associated polyposis (MAP) pedigrees. MAP is an autosomal-recessive disease characterized by multiple colorectal adenomas and cancer. Immunohistochemistry of mismatch repair and APC proteins was performed. DNA isolated from blood lymphocytes and formalin-fixed or paraffin-embedded SGHs was PCR amplified and sequenced. In the SGH patients, we detected T1796A heterozygous substitution (V600E) in the BRAF gene. Compound biallelic germline MYH mutations (Y165C/G382D, R168H/379delC, and Y90X/delGGA464) were detected in the MAP patients. In contrast to the majority of melanocytic lesions, activating hotspot mutations in BRAF have not been involved so far in the pathogenesis of SGH. BRAF mutation is not a specific marker of melanocytic cancerogenesis, and it can also be involved in SGHs. In both melanocytic and non-melanocytic skin tumors, BRAF mutation is linked to early tumorigenesis events.

Microsatellite instability did not predict individual survival of unselected patients with colorectal cancer

INTRODUCTION

High microsatellite instability (MSI-H) occurs in about 15% of colorectal cancers (CRC) and clinical as well as pathological features differ from tumours exhibiting low microsatellite instability (MSI-L) or microsatellite stability (MSS). Conflicting data exists about the relevance of MSI in predicting the prognosis and benefit of 5-fluorouracil (5-FU) based chemotherapy in patients with CRC. We investigated the usefulness of MSI as a predictor of distinct clinical attributes influencing recurrence rate and disease-free survival (DFS) subject to the use of adjuvant or palliative chemotherapy with 5-FU in stage II- stage IV CRC.

METHODS

We collected data and tumours of 416 consecutive stage I to IV CRC patients from 2000 to 2002, and followed them for a median time of 33 months. Microsatellite loci recommended by the National Cancer Institute were analysed. Cox proportional hazard modelling was used to compare clinical data and survival as well as associations for MSI and 5-FU treatment status of patients with MSI-H, MSI-L or MSS CRC.

RESULTS

We identified 52 MSI-H (13%), 21 MSI-L (5%) and 343 MSS (82%) tumours. CRC with MSI-H tended to have a decreased likelihood of metastasising to regional lymph nodes (p=0.055), whilst age of diagnosis and tumour location did not differ. In an analysis that did not take into account the use of chemotherapy, univariate and multivariate analyses failed to show a difference between MSI-H and MSS groups with respect to disease-free and overall survival. Furthermore, survival under application of 5-FU did not correlate with MSI status.

CONCLUSION

No clear influence of MSI status on overall survival and response to 5-FU chemotherapy was found.

Muir?Torre syndrome: Diagnostic and screening guidelines

A 65-year-old man presented with a history of multiple skin coloured papules on his face that were asymptomatic. He had an adenocarcinoma resected from his proximal colon 12 years prior to presentation as well as a family history of colon cancer on the maternal side. Diagnostic biopsies showed the lesions to be sebaceous adenomas and epitheliomas and the diagnosis of Muir-Torre syndrome was made. The sebaceous tumour tissue showed microsatellite instability and immunohistochemical staining indicated diminished expression in the DNA mismatch-repair protein complex MSH2/MSH6. Genetic analysis showed a germline mutation in the MSH2 gene confirming the diagnosis of Muir-Torre syndrome. The patient and his first-degree relatives have been referred for genetic counselling and screening. We review the diagnostic criteria in this syndrome and review the recommended screening guidelines.

Value of MLH1 and MSH2 Mutations in the Appearance of Muir–Torre Syndrome Phenotype in HNPCC Patients Presenting Sebaceous Gland Tumors or Keratoacanthomas

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal-dominant disorder characterized by predisposition to colorectal cancer and extracolonic malignancies, frequent multiple primary tumors in the same patient, and early age of cancer onset. A main clinical variant of Lynch syndrome, Muir-Torre syndrome (MTS) is characterized by the association between one or more visceral malignancies, with at least one sebaceous skin tumor or keratoacanthoma. In our study, we have screened a cohort of 538 HNPCC patients, related to 57 HNPCC families, to detect sebaceous skin tumors and keratoacanthomas and the role of mismatch repair (MMR) genes, MLH1, MSH2, and MSH6, in their pathogenesis. Among the 57 HNPCC families, we have identified four MTS families and one suspected MTS family, in which sebaceous carcinoma was found in one HNPCC mutation carrier subject who did not show visceral malignancy. In four of these families, linked to two MLH1 mutations and to two MSH2 mutations, biomolecular characterization showed concordance among immunohistochemistry analysis and gene mutations. The evidences of our investigations show that MLH1 and MSH2 gene mutations have an equivalent etiopathological role both for Lynch syndrome and for MTS; hence, we propose a broadened clinical criteria for definition of Lynch syndrome that will include sebaceous adenoma, carcinoma, and keratoacanthoma.