Muir-Torre phenotype has a frequency of DNA mismatch-repair-gene mutations similar to that in hereditary nonpolyposis colorectal cancer families defined by the Amsterdam criteria

Determination of the frequency and distribution of APC, PIK3CA, and SMAD4 gene mutations in Ugandan patients with colorectal cancer

Uganda is a developing low-income country with a low incidence of colorectal cancer, which is steadily increasing. Ugandan colorectal cancer (CRC) patients are young and present with advanced-stage disease. In our population, there is a scarcity of genetic oncological studies, therefore, we investigated the mutational status of CRC tissues, focusing in particular on the adenomatous polyposis coli (APC), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), and SMAD4 genes. Our objective was to determine whether there were any differences between other populations and Ugandan patients. We performed next-generation sequencing on the extracted DNA from formalin-fixed paraffin-embedded adenocarcinoma samples from 127 patients (mean (SD) age: 54.9 (16.0) years; male:female sex ratio: 1.2:1). Most tumours were located in the rectum 56 (44.1%), 14 (11%) tumours were high grade, and 96 (75.6%) were moderate grade CRC. Stage III + IV CRC tumours were found in 109 (85.8%) patients. We identified 48 variants of APC, including 9 novel APC mutations that were all pathogenic or deleterious. For PIK3CA, we found 19 variants, of which 9 were deleterious or pathogenic. Four PIK3CA novel pathogenic or deleterious variants were included (c.1397C > G, c.2399_2400insA, c.2621G > C, c.2632C > G). Three SMAD4 variants were reported, including two pathogenic or deleterious variants (c.1268G > T, c.556dupC) and one tolerant (c.563A > C) variant. One novel SMAD4 deleterious mutation (c.1268G > T) was reported. In conclusion, we provide clinicopathological information and new genetic variation data pertinent to CRC in Uganda.

Periocular sebaceous carcinoma: updates in the diagnosis, treatment, staging, and management

Periocular sebaceous carcinoma (PSC) is a rare, aggressive, and potentially metastatic adnexal malignancy. Due to the ability of PSC to resemble several benign and malignant conditions, diagnosis is often delayed or mistaken. In addition, even with a known diagnosis, choosing the right treatment is still an open debate. For this reason, we decided to review the most up-to-date literature on PSC and propose a dedicated procedural protocol to help clinicians when dealing with PSC. A PubMed search was carried out using the terms "Sebaceous Carcinoma", "Adnexal Periocular Cancer", "Sebaceous Carcinoma AND eyelid", "Periocular Sebaceous Carcinoma", and "Ocular Adnexa". Pertinent studies published in English from 1997 up to December 2022 were compared to the selection criteria and if suitable, included in this review. Through the initial search, 84 articles were selected. Of these, 36 were included in the final study. Several papers explored different diagnostic and therapeutic strategies regarding PSC diagnosis and management. In light of the current literature review and the multidisciplinary experience of three clinical centers, a dedicated procedural protocol is proposed. PSC diagnosis may be achieved through accurate clinical evaluation, but it requires histopathologic confirmation, which can be challenging. Dermoscopy, in vivo reflectance confocal microscopy, and optical coherence tomography may facilitate PSC clinical examination, while immunohistochemistry stains may support histological diagnosis. Appropriate disease staging is necessary before choosing the treatment, as local disease requires radically different treatment compared to advanced disease. In addition, recent innovations in nonsurgical treatments, including radio-chemotherapy, immunotherapy, and targeted therapy, may be a viable option in the most challenging cases.

Role of the NLRP1 inflammasome in skin cancer and inflammatory skin diseases

Inflammasomes are cytoplasmic protein complexes that play a crucial role in protecting the host against pathogenic and sterile stressors by initiating inflammation. Upon activation, these complexes directly regulate the proteolytic processing and activation of proinflammatory cytokines interleukin (IL)-1β and IL-18 to induce a potent inflammatory response, and induce a programmed form of cell death called pyroptosis to expose intracellular pathogens to the surveillance of the immune system, thus perpetuating inflammation. There are various types of inflammasome complexes, with the NLRP1 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-1) inflammasome being the first one identified and currently recognized as the predominant inflammasome sensor protein in human keratinocytes. Human NLRP1 exhibits a unique domain structure, containing both an N-terminal pyrin (PYD) domain and an effector C-terminal caspase recruitment domain (CARD). It can be activated by diverse stimuli, such as viruses, ultraviolet B radiation and ribotoxic stress responses. Specific mutations in NLRP1 or related genes have been associated with rare monogenic skin disorders, such as multiple self-healing palmoplantar carcinoma; familial keratosis lichenoides chronica; autoinflammation with arthritis and dyskeratosis; and dipeptidyl peptidase 9 deficiency. Recent research breakthroughs have also highlighted the involvement of dysfunctions in the NLRP1 pathway in a handful of seemingly unrelated dermatological conditions. These range from monogenic autoinflammatory diseases to polygenic autoimmune diseases such as vitiligo, psoriasis, atopic dermatitis and skin cancer, including squamous cell carcinoma, melanoma and Kaposi sarcoma. Additionally, emerging evidence implicates NLRP1 in systemic lupus erythematosus, pemphigus vulgaris, Addison disease, Papillon-Lefèvre syndrome and leprosy. The aim of this review is to shed light on the implications of pathological dysregulation of the NLRP1 inflammasome in skin diseases and investigate the potential rationale for targeting this pathway as a future therapeutic approach.

Genetics of adnexal tumors: An update

Cutaneous adnexal tumors form a vast heterogeneous group that include frequent entities that are mostly benign, as well as rare tumors that are occasionally malignant. In contrast to cutaneous tumors arising from the interfollicular epidermis that develop as a result of accumulation of UV-induced DNA damage (basal cell carcinoma, squamous cell carcinoma), the oncogenesis of adnexal tumors is related to a broad spectrum of genetic mechanisms (e.g., point mutation, fusion genes, viral integration, etc.). In this setting, specific and recurrent genetic alterations have been progressively reported, and these allow better classification of these entities. For certain of them, immunohistochemical tools are now available, enabling precise integrated histological and molecular diagnosis since certain entities are linked to well-defined alterations. In this context, we aim in this review to summarize the main molecular tools currently available for the classification of adnexal tumors.

Early age of onset and broad cancer spectrum persist in MSH6- and PMS2-associated Lynch syndrome

PURPOSE

This study aimed to characterize MSH6/PMS2-associated mismatch repair-deficient (MMR-D)/microsatellite instability-high (MSI-H) tumors, given revised guidelines suggesting more modest phenotypes.

METHODS

Patients who consented to Institutional Review Board-approved protocols of tumor/germline sequencing or Lynch syndrome registry at a single institution from February 2005 to January 2021 with germline, heterozygous MSH6/PMS2 pathogenic/likely pathogenic variants were identified. Clinical data were abstracted and correlated with MMR/microsatellite instability status using nonparametric tests.

RESULTS

We identified 243 patients (133 sequencing, 110 registry) with germline MSH6/PMS2 pathogenic/likely pathogenic variants; 186 (77%) had >1 cancer. Of 261 pooled tumors, colorectal cancer (CRC) and endometrial cancer (EC) comprised 55% and 43% of cancers in MSH6 and PMS2, respectively; 192 tumors underwent molecular assessments and 122 (64%) were MMR-D/MSI-H (77 in MSH6, 45 in PMS2). MMR-D/MSI-H cancers included CRC (n = 56), EC (n = 35), small bowel cancer (n = 6), ovarian cancer (n = 6), urothelial cancer (n = 5), pancreas/biliary cancer (n = 4), gastric/esophageal cancer (n = 3), nonmelanoma skin tumors (n = 3), prostate cancer (n = 2), breast cancer (n = 1), and central nervous system/brain cancer (n = 1). Among MMR-D/MSI-H CRC and EC, median age of diagnosis was 51.5 (range = 27-80) and 55 (range = 39-74) years, respectively; 9 of 56 (16%) MMR-D/MSI-H CRCs were diagnosed at age <35 years.

CONCLUSION

MSH6/PMS2 heterozygotes remain at risk for a broad spectrum of cancers, with 16% of MMR-D/MSI-H CRCs presenting before upper threshold of initiation of colonoscopy per guidelines.

Bindehautdegenerationen und -neoplasien

Erhabenheiten der Bindehaut entstehen durch Gewebevermehrung, die entweder degenerativ oder neoplastisch, aber auch entzündlich sein können. In diesem Artikel werden degenerative (Pterygium und Pinguecula) sowie benigne und maligne neoplastische Bindehautveränderungen (epitheliale, melanozytäre und vaskuläre Tumoren, Choristome sowie Metastasen) bezüglich der Pathogenese, Symptome, Diagnostik und aktuellem Stand der Behandlung dargestellt.

[Conjunctival Degeneration and Neoplasia]

Conjunctival tumors result from gain of tissue, which can be either degenerative or neoplastic, but also inflammatory. In this article, degenerative (pterygium and pinguecula) as well as benign and malignant neoplastic conjunctival changes (epithelial, melanocytic and vascular tumors, choristomas as well as metastases) are discussed with regard to pathogenesis, symptoms, diagnostics and current status of treatment.

Kidney Transplant Recipient With Multiple Contemporaneous Malignancies Secondary to Muir-Torre Syndrome

Muir-Torre Syndrome (MTS) is a rare autosomal-dominant genetic condition linked to germline mutations in DNA mismatch repair (MMR) genes, resulting in microsatellite instability. It is considered a variant of Lynch syndrome characterized by the association of at least one sebaceous skin tumor and at least one internal malignancy. In addition, it has been shown that a latent phenotype of MTS might be unmasked in transplant organ recipients and immunosuppressed patients. The diagnosis and treatment of such cases require a multidisciplinary approach. Here, we present a case of a kidney transplant recipient who developed multiple sebaceous carcinomas 16 years after kidney transplantation and daily immunosuppressive medication. The patient then developed multiple contemporaneous internal malignancies in the esophagus and colon with metastases to the lung, thyroid, and lymph nodes, all of which were eventually linked to MTS. To our knowledge, this is the first reported case of MTS in the Arab world and the first reported case of esophageal cancer in relation to MTS in a transplant recipient. Because patients with MTS have a high tendency of developing malignancies, patients with a strong family history of malignancies, any known mutations, or an immunocompromised status should be included in an extensive screening program.

Molecular Genetics of Sebaceous Neoplasia

Sebaceous neoplasia primarily includes sebaceous adenoma, sebaceoma, and sebaceous carcinoma (SC). Sebaceous adenoma, sebaceoma, and a subset of cutaneous SC are frequently associated with defective DNA mismatch repair resulting from mutations in MLH1, MSH2, or MSH6. These tumors can be sporadic or associated with Muir-Torre syndrome. SCs without defective DNA mismatch repair have ultraviolet signature mutation or paucimutational patterns. Ocular SCs have low mutation burdens and frequent mutations in ZNF750. Some ocular sebaceous carcinomas have TP53 and RB1 mutations similar to cutaneous SC, whereas others lack such mutations and are associated with human papilloma virus infection.

A Case of Muir-Torre Syndrome

Muir-Torre syndrome (MTS) is an autosomal dominant condition characterized by dermatological tumors along with visceral malignancies. The dermatological manifestations include recurrent sebaceous adenomas and keratoacanthomas. The commonly seen visceral malignancies are colorectal, gynecological, and urological. It is a variant of hereditary non-polyposis colorectal carcinoma syndrome (HNPCC). The underlying genetic mechanism is germline mutations in the DNA mismatch repair (MMR) genes leading to microsatellite instability (MSI), conferring an increased risk of developing malignancies. This is a case of a 57-year-old male patient with a history of colon cancer diagnosed at age 32 and multiple sebaceous adenomas. The patient also has a strong family history of cancer. They were referred to oncology after the immunohistochemical staining of a sebaceous adenoma showed loss of expression for MSH2 and MSH6. Next-generation sequencing identified a mutation in the MSH2 gene. These patients require genetic testing, counseling, and close follow-up with regular screening for cancer.

Sebaceous Tumors of the Skin: A Study of 145 Lesions From 136 Patients Correlating Pathologic Features and DNA Mismatch Repair Staining Pattern

ABSTRACT

Sebaceous neoplasms occur sporadically or in the setting of Muir-Torre syndrome. The data regarding the correlation of pathologic features and DNA mismatch repair (MMR) staining pattern in sebaceous tumors of the skin are very scanty and based on relatively small series of patients. The goal of this study was to correlate MMR staining pattern with selected morphological features in a series of 145 sebaceous neoplasms (sebaceous adenoma, sebaceoma, and extraocular sebaceous carcinoma) from 136 patients. Cystic change, intratumoral mucin deposits, squamous metaplasia in the absence of keratoacanthoma-like changes, ulceration, intratumoral and peritumoral lymphocytes (in cases without epidermal ulceration), and intertumoral heterogeneity proved to be significantly associated with MMR deficiency. Identification of any of these changes, alone or in combination, should prompt further investigation of the patient to exclude Muir-Torre Syndrome. Our study also confirms the previously published observation that the diagnosis and tumor location are significantly associated with MMR deficiency.

Lynch syndrome with exclusive skin involvement: time to consider a molecular definition?

Muir-Torre syndrome (MTS) is clinically characterized by the occurrence of skin, usually sebaceous, and visceral tumors in the same individual. The most common underlying mechanism is a constitutional defect of the mismatch repair (MMR) genes that cause Lynch syndrome (LS). Herewithin we report on a 76 years-old male patient heterozygous for a pathogenic MSH2 missense substitution who presented with a striking cutaneous phenotype in the absence of typical LS visceral tumors. The patient developed 20 skin tumors, including sebaceous adenomas/carcinomas and keratoacanthomas. Two skin tumors showed immunohistochemical loss of MSH2 and MSH6 expression. There was no apparent family history of neoplasia. Based on the variable involvement of the skin and internal organs, we suggest that the definition of tumor associations that are often observed as variants of inherited tumor syndromes, such as MTS, should be guided by the underlying molecular bases. In addition, the presence of multiple sebaceous tumors, especially if showing MMR deficiency, appears to be a very strong indicator of a constitutional MMR gene defect. The reasons underlying the high phenotypic variability of cutaneous phenotypes associated with constitutional MMR defects are yet to be determined.

Muir-Torre Syndrome: A Case Report in a Woman Without Personal Cancer History

We report a case of a 68-year-old white woman presenting with 5 sebaceous neoplasms, ranging from sebaceous adenoma to sebaceoma on histopathology. Despite the lack of a personal cancer history, her multiple sebaceous neoplasms and a paternal history of colon cancer prompted testing her sebaceous adenomas for microsatellite instability (MSI) by immunohistochemistry. The results showed retained nuclear expressions of MLH1 and PMS2 while MSH2 and MSH6 proteins were absent. The tumor infiltrating lymphocytes expressed both MSH2 and MSH6, providing reliable internal positive controls. Having a high probability for MSI, she was found to be heterozygous for a germline point mutation in MSH2 gene, where a pathologic variant, c.1165C > T (p.Arg389*), determined by sequencing confirmed Muir-Torre syndrome (MTS). On further genetic counseling recommendations, one of her 2 sons was found to have colon cancer in the context of his MTS. In this article, we highlight and review the implications of MSI testing by both immunohistochemistry and sequencing as they relate to confirming the diagnosis of a suspected case of MTS.

Mechanisms shaping the mutational landscape of the FRA3B/FHIT-deficient cancer genome

Genome instability is an enabling characteristic of cancer that facilitates the acquisition of oncogenic mutations that drive tumorigenesis. Underlying much of the instability in cancer is DNA replication stress, which causes both chromosome structural changes and single base-pair mutations. Common fragile sites are some of the earliest and most frequently altered loci in tumors. Notably, the fragile locus, FRA3B, lies within the fragile histidine triad (FHIT) gene, and consequently deletions within FHIT are common in cancer. We review the evidence in support of FHIT as a DNA caretaker and discuss the mechanism by which FHIT promotes genome stability. FHIT increases thymidine kinase 1 (TK1) translation to balance the deoxyribonucleotide triphosphates (dNTPs) for efficient DNA replication. Consequently, FHIT-loss causes replication stress, DNA breaks, aneuploidy, copy-number changes (CNCs), small insertions and deletions, and point mutations. Moreover, FHIT-loss-induced replication stress and DNA breaks cooperate with APOBEC3B overexpression to catalyze DNA hypermutation in cancer, as APOBEC family enzymes prefer single-stranded DNA (ssDNA) as substrates and ssDNA is enriched at sites of both replication stress and DNA breaks. Consistent with the frequent loss of FHIT across a broad spectrum of cancer types, FHIT-deficiency is highly associated with the ubiquitous, clock-like mutation signature 5 occurring in all cancer types thus far examined. The ongoing destabilization of the genome caused by FHIT loss underlies recurrent inactivation of tumor suppressors and activation of oncogenes. Considering that more than 50% of cancers are FHIT-deficient, we propose that FRA3B/FHIT fragility shapes the mutational landscape of cancer genomes.

Sebaceous tumours: more than skin deep

CLINICAL PRESENTATION: A 77-year-old man presented to our skin cancer centre with various cutaneous tumours occurring in 2006-2017. Histopathology showed a 'hidradenocarcinoma' on the left upper back (2006) and a sebaceous adenoma (figure 1) on the left shoulder (2011). In 2017, he developed a sebaceous carcinoma on the middle upper back, which manifested as a slowly enlarging, asymptomatic nodule. Medical history was significant for curative resection of colorectal cancer in 1988.gutjnl;67/11/1957/F1F1F1Figure 1Clinical appearance of the sebaceous adenoma on the patient's left shoulder in 2011.The most recent lesion was subjected to extensive immunohistochemical assessment. The neoplastic cells were positive for cytokeratin 5/6, cytokeratin 7, cluster of differentiation antigen 10, adipophilin, androgen receptor, epithelial membrane antigen, KI67 antigen, MLH1 and PMS2, but stained negative for gross cystic disease fluid protein 15, prostate-specific antigen, carbohydrate antigen 19/9, CDX2 protein, hepatocyte-specific antigen, carcinoembryonic antigen, cluster of differentiation antigen 117 and cytokeratin 19. Given the variety of histological manifestations of the patient's skin neoplasms, further studies were performed. They revealed positive nuclear expression signals for MLH1, MSH6 and PMS2, whereas MSH2 expression was absent in almost all tumour cells (figure 2). Positron emission tomography (PET)/CT and colonoscopy did not detect any pathological findings. However, molecular genetic analysis of peripheral blood showed a heterozygous deletion of exon 7 of the MSH2 gene. Subsequently, several family members tested positive for MSH2 mutations and underwent genetic counselling.gutjnl;67/11/1957/F2F2F2Figure 2(A-D) Histopathological images of the patient's most recent lesion (diaminobenzidine, original magnification, ×100). The tumour cells demonstrated strong nuclear positivity for MLH1 (A) and PMS2 (B), but were essentially negative for MSH6 (C) and MSH2 (D).

QUESTION

What is your diagnosis?

DIAGNOSIS

Muir-Torre syndrome (MTS).

MSH6, Past and Present and Muir-Torre Syndrome-Connecting the Dots

Sebaceous neoplasms such as adenoma, sebaceoma, and carcinoma, although sporadic in their occurrence, are clinically significant because of their association with Muir-Torre syndrome (MTS). MTS is a rare autosomal dominant genodermatosis characterized by the occurrence of sebaceous neoplasms and/or keratoacanthomas and visceral malignancies. MTS is usually the result of germline mutations in the DNA mismatch repair genes MSH2 and, albeit less commonly, MLH1. Although less know, MSH6 is yet another key player. Evidence from Lynch syndrome indicates that pathogenic germline mutations in MSH6 are typically microsatellite stable and have a clinical presentation that differs from that associated with germline mutations in MSH2 and/or MLH1. Given this unique mutator phenotype of MSH6, the primary aim of this review was to underscore the clinical manifestations associated with pathogenic mutations in MSH6 in patients with MTS. As the current clinical and laboratory work-up of MTS is geared toward patients harboring a germline mutation in MSH2 and/or MLH1, an additional aim was to provide a scaffolding for the work-up of a patient presenting with an isolated germline mutation in MSH6.

Folliculosebaceous neoplasms: A review of clinical and histological features

Numerous benign and occasionally malignant tumors arise from the folliculosebaceous apparatus. Confusing terminology, rarity of malignant variants and overlapping histological features can lead to diagnostic uncertainty. This review highlights the clinical and histopathological features that help to classify these entities, as well as the various syndromes associated with certain members of this large family of tumors.

Molecular pathology in real time

With the development of sophisticated individualized therapeutic approaches, the role of pathology in classification of tumors is enormously increasing. The solely morphological characterization of neoplastic process is no more sufficient for qualified decision on optimal therapeutic approach. Thus, morphologic diagnosis must be supplemented by molecular analysis of the lesion with emphasis on the detection of status of certain markers used as predictive factors for targeted therapy. Both intrinsic and acquired types of intratumor heterogeneity have an impact at various moments of cancer diagnostics and therapy. The primary heterogeneity of neoplastic tissue represents a significant problem in patients, where only limited biopsy samples from the primary tumor are available for diagnosis, such as core needle biopsy specimens in breast cancer, transthoracic or endobronchial biopsies in lung cancer, or endoscopic biopsies in gastric cancer. Detection of predictive markers may be influenced by this heterogeneity, and the marker detection may be falsely negative or (less probably) falsely positive. In addition, as these markers are often detected in the tissue samples from primary tumor, the differences between molecular features of the primary lesion and its metastases may be responsible for failure of systemic therapy in patients with discordant phenotype between primary and metastatic disease. The fact of tumor heterogeneity must be taken into consideration already in establishing pathological diagnosis. One has to be aware that limited biopsy specimen must not always be fully representative of the entire tumor volume. To overcome these limitations, there does not exist one single simple solution. Examination of more tissue (preference of surgical resection specimens over biopsies, whenever possible), use of ultra-sensitive methods able to identify the minute subclones as a source of possible resistance to treatment, and detection of secondary molecular events from the circulating tumor cells or circulating cell-free DNA are potential solutions how to handle this issue.

Multiple Sebaceous Adenomas and Extraocular Sebaceous Carcinoma in a Patient with Multiple Sclerosis: Case Report and Review of Literature

Background:

Sebaceous carcinomas are relatively rare cutaneous tumors; there are fewer than 600 cases reported. They most commonly arise within the meibomian gland of the eyelid; fewer than 150 of the reported cases were extraocular. These tumors have a high incidence of local recurrence and regional metastasis. The relationship of sebaceous tumors and visceral malignancy is well established in the literature.

Objective:

We describe a 44-year-old white female with chronic progressive multiple sclerosis who developed multiple scalp sebaceous adenomas and a solitary sebaceous carcinoma.

Conclusion:

Extraocular sebaceous carcinomas are rare tumors with high incidence of local recurrence and regional metastasis. Surgery with wide surgical margins is the standard treatment. We report the first case of multiple sebaceous tumors in a patient with multiple sclerosis. The presence of sebaceous tumors warrants a search for an internal malignancy. Literature on sebaceous tumors and their relationship with visceral malignancies and immunologic disorders is discussed. Literature on sebaceous carcinoma with special attention to extraocular sebaceous carcinoma is also discussed.

Arachidonic Acid-Derived Bioactive Lipids: Their Role and the Role for Their Inhibitors in Dermatology

Background:

In addition to corticosteroids, there are increasing numbers of anti-inflammatory agents that specifically target bioactive lipids generated from arachidonic acid. Knowledge of the diverse mechanisms of action of these different bioactive lipids holds promise in the therapy of a wide spectrum of cutaneous and systemic disorders.

Objective:

Therapeutic manipulations of these lipid molecules through inhibition, stimulation, or direct replacement have broad physiologic effects. These therapeutic strategies not only modulate inflammation, pain, and hemostatic parameters, they also play a role in cardiac, respiratory, renal, and gastrointestinal function and disease, as well as in angiogenesis and in factors that control cell growth and apoptosis important in carcinogenesis.

Conclusion:

Newer drug discovery methods, including combinatorial chemistry with molecular modeling, have made it possible to develop inhibitors and analogs with increasing specificity and bioactivity and decreasing toxicity. Although the application of these analogs and inhibitors for cutaneous disease is limited today, either as primary agents or adjuvant therapy, these drugs will have a place in our therapeutic regimes of the future. We present a review of the therapeutic agents now available from manipulation of these bioactive lipids, and their role and future in dermatology.

Muir-Torre Syndrome: A Case Associated with an Infrequent Gene Mutation

Muir-Torre syndrome is a rare, autosomal dominant genodermatosis characterized by the presence of at least one sebaceous gland neoplasm, associated with an underlying visceral malignancy. Muir-Torre syndrome is believed to be a subtype of Lynch Syndrome. Affected individuals are found to have germline mutations predominantly in DNA mismatch repair gene MSH2, and much less frequently, MLH1. The authors report the case of a 55-year-old woman presenting with multiple cutaneous neoplasms including sebaceoma, basal cell carcinoma, and squamous cell carcinoma; personal history of colorectal and endometrial cancer; and family history of colorectal cancer; found to have a deletion at mismatch repair gene MLH1. It is important to recognize the role of these less common gene deletions in producing the Muir-Torre syndrome phenotype, and consider the correlation of cutaneous manifestations with internal disease. The authors discuss the clinical presentation of Muir-Torre syndrome, methods of diagnosis, and the importance of regular medical surveillance to detect and prevent disease progression in Muir-Torre syndrome patients and their family members.

Generational Expression of Muir-Torre Syndrome in a Canadian Family

Muir-Torre syndrome (MTS) is a rare autosomal dominant inherited genodermatosis that is considered to be a phenotypic subtype of hereditary nonpolyposis colorectal cancer (HNPCC), commonly referred to as Lynch syndrome. We describe the clinical course of a 57-year-old female patient with MTS. She has a confirmed HMSH2 mutation. Recently she presented with two nodular lesions. Histologic examination confirmed these lesions to be sebaceous neoplasms. The patient has a history of endometrial and colorectal adenocarcinoma as well as several nonspecific sebaceous lesions throughout her life. She has a confirmed extensive family history of MTS with both male and female family members harbouring either HMLH1 or HSMH2 mutations. Affected relatives have presented at different ages throughout their lives with cutaneous neoplasms and visceral malignancies, including malignancies rarely associated with MTS. MTS presents a diagnostic challenge for clinicians. The case demonstrates that the management of MTS, a potentially underreported syndrome, requires a multiprofessional approach incorporating vigilance, screening, and expert knowledge for successful diagnosis and potentially improved prognosis for patients and their families. The case also demonstrates the varied heritability of MTS and prompts the question of how MTS is expressed in succeeding generations.

Hereditary Syndromes Manifesting as Endometrial Carcinoma: How Can Pathological Features Aid Risk Assessment?

Endometrial carcinoma is the most common gynecological tumor worldwide. It can be the presenting malignancy, acting as the harbinger, of an undiagnosed hereditary syndrome. Up to 50% of females with Lynch syndrome present in this manner. Differentiation between Lynch, Muir-Torre, and Cowden syndromes can at times be challenging due to the overlapping features. Our review emphasizes on the strengths, pitfalls, and limitations of microscopic features as well as immunohistochemical and polymerase chain reaction- (PCR-) based tests used by laboratories to screen for DNA mismatch repair (MMR) and PTEN gene mutations in patients to enable a more targeted and cost effective approach in the use of confirmatory gene mutational analysis tests. This is crucial towards initiating timely and appropriate surveillance measures for the patient and affected family members. We also review the evidence postulating on the possible inclusion of uterine serous carcinoma as part of the spectrum of malignancies seen in hereditary breast and ovarian carcinoma syndrome, driven by mutations in BRCA1/2.

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.

Muir-Torre syndrome: case report and molecular characterization

CONTEXT

Muir-Torre syndrome is a rare autosomal dominant genodermatosis caused by mutations in the mismatch repair genes. It is characterized by the presence of sebaceous skin tumors and internal malignancies, affecting mainly the colon, rectum and urogenital tract. Awareness of this syndrome among physicians can lead to early diagnosis of these malignancies and a better prognosis.

CASE REPORT

We report the case of a Chilean patient who, over the course of several years, had multiple skin lesions, endometrial cancer and colon cancer. The syndrome was diagnosed using molecular techniques such as microsatellite instability analysis, immunohistochemistry and DNA sequencing, which allowed us to find the causative mutation.

CONCLUSION

Molecular diagnostics is a highly useful tool, since it allows clinicians to confirm the presence of mutations causing Muir-Torre syndrome. It is complementary to the analysis of the clinical data, such as dermatological presentation, presence of visceral malignancies and family history of colorectal tumors, and it provides important knowledge to help physicians and patients choose between treatment options.

FANCJ localization by mismatch repair is vital to maintain genomic integrity after UV irradiation

Nucleotide excision repair (NER) is critical for the repair of DNA lesions induced by UV radiation, but its contribution in replicating cells is less clear. Here, we show that dual incision by NER endonucleases, including XPF and XPG, promotes the S-phase accumulation of the BRCA1 and Fanconi anemia-associated DNA helicase FANCJ to sites of UV-induced damage. FANCJ promotes replication protein A phosphorylation and the arrest of DNA synthesis following UV irradiation. Interaction defective mutants of FANCJ reveal that BRCA1 binding is not required for FANCJ localization, whereas interaction with the mismatch repair (MMR) protein MLH1 is essential. Correspondingly, we find that FANCJ, its direct interaction with MLH1, and the MMR protein MSH2 function in a common pathway in response to UV irradiation. FANCJ-deficient cells are not sensitive to killing by UV irradiation, yet we find that DNA mutations are significantly enhanced. Thus, we considered that FANCJ deficiency could be associated with skin cancer. Along these lines, in melanoma we found several somatic mutations in FANCJ, some of which were previously identified in hereditary breast cancer and Fanconi anemia. Given that, mutations in XPF can also lead to Fanconi anemia, we propose collaborations between Fanconi anemia, NER, and MMR are necessary to initiate checkpoint activation in replicating human cells to limit genomic instability.

Muir-Torre Syndrome in a Middle-Aged Chinese Patient with Sebaceous Carcinoma of the Eyelid

Muir-Torre syndrome is a rare, autosomal dominant condition characterized by the presence of a skin tumor of sebaceous differentiation and visceral malignancies. We reviewed the case of a 46-year-old Chinese man who had a bleeding mass over the right upper eyelid. He had a history of colon cancer and a family history satisfying the Amsterdam criteria for hereditary non-polyposis colorectal cancer syndrome with germline mutation in the MutS homolog-2 gene. The eyelid lesion was excised completely and submitted for histopathologic examination which showed sebaceous carcinoma. Frozen section and conjunctival map biopsy showed no residual malignancy or local metastasis. Post-operative positron-emission tomography with combined computed tomography did not reveal any residual or visceral malignancy. He had no recurrence in the 32-month follow-up period. We should consider Muir-Torre syndrome in patients with sebaceous carcinoma, especially in the presence of personal and/or family history of visceral malignancies.

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.

Identification of patients at risk for hereditary colorectal cancer

Diagnosis of hereditary colorectal cancer syndromes requires clinical suspicion and knowledge of such syndromes. Lynch syndrome is the most common cause of hereditary colorectal cancer. Other less common causes include familial adenomatous polyposis (FAP), Peutz-Jeghers syndrome (PJS), juvenile polyposis syndrome, and others. There have been a growing number of clinical and molecular tools used to screen and test at risk individuals. Screening tools include diagnostic clinical criteria, family history, genetic prediction models, and tumor testing. Patients who are high risk based on screening should be referred for genetic testing.

Simultaneous Muir-Torre and Turcot's syndrome: A case report and review of the literature

Background:

Muir-Torre syndrome (MTS) is an autosomal dominant syndrome characterized by neoplasms of the sebaceous gland or keratoacanthomas, in addition to visceral malignancies. Cerebral neoplasms in patients with hereditary nonpolyposis colorectal cancer (HNPCC) or familial adenomatous polyposis suffer from Turcot's syndrome. Genetic mutations in MutS homolog (MSH)-2, MutL homolog (MLH)-1, and MutS homolog (MSH)-6 DNA mismatch repair genes are the most common in MTS with MSH-2 being the most predominant. In HNPCC MLH-1 and MSH-2 mutations are approximately equal in prevalence.

Case Description:

We present the case of a 58-year-old male with a prior history of being treated for colonic adenocarcinoma and skin lesions leading to a diagnosis of MTS. The patient later developed a World Health Organization (WHO) grade 4 glioma requiring surgical resection. Pathology revealed mutations in MSH-2 and MSH-6 mismatch repair genes.

Conclusions:

This case represents the first report of Turcot's and MTS with extensive molecular testing on the cerebral neoplasm demonstrating a molecular relationship between Turcot's and MTS and only the second published report of simultaneous Turcot's and MTS.

[Muir-Torre syndrome with previously undescribed frameshift mutation in the MSH2 gene]

Muir-Torre syndrome (MTS) is a rare phenotypic variant of hereditary non-polyposis colorectal carcinoma (HNPCC, Lynch syndrome), in which patients, in addition to visceral carcinomas, develop skin tumors. Multiple keratoacanthomas and basal cell carcinomas with sebocytic differentiation are characteristic as well as multiple benign and malignant tumors of the sebaceous glands, such as sebaceous adenoma, sebaceous epithelioma (sebaceoma) and sebaceous carcinoma. Particularly Cystic tumors of the sebaceous glands are especially suggestive of MTS. In genetically predisposed persons, cutaneous and visceral tumors are diagnosed at an average age of 53 years. Here we present an interesting case of a 65-year-old man in whom molecular genetic tests revealed a novel mutation in the MSH2 gene, leading to a frame shift within the gene.

Initiation of genome instability and preneoplastic processes through loss of Fhit expression

Genomic instability drives tumorigenesis, but how it is initiated in sporadic neoplasias is unknown. In early preneoplasias, alterations at chromosome fragile sites arise due to DNA replication stress. A frequent, perhaps earliest, genetic alteration in preneoplasias is deletion within the fragile FRA3B/FHIT locus, leading to loss of Fhit protein expression. Because common chromosome fragile sites are exquisitely sensitive to replication stress, it has been proposed that their clonal alterations in cancer cells are due to stress sensitivity rather than to a selective advantage imparted by loss of expression of fragile gene products. Here, we show in normal, transformed, and cancer-derived cell lines that Fhit-depletion causes replication stress-induced DNA double-strand breaks. Using DNA combing, we observed a defect in replication fork progression in Fhit-deficient cells that stemmed primarily from fork stalling and collapse. The likely mechanism for the role of Fhit in replication fork progression is through regulation of Thymidine kinase 1 expression and thymidine triphosphate pool levels; notably, restoration of nucleotide balance rescued DNA replication defects and suppressed DNA breakage in Fhit-deficient cells. Depletion of Fhit did not activate the DNA damage response nor cause cell cycle arrest, allowing continued cell proliferation and ongoing chromosomal instability. This finding was in accord with in vivo studies, as Fhit knockout mouse tissue showed no evidence of cell cycle arrest or senescence yet exhibited numerous somatic DNA copy number aberrations at replication stress-sensitive loci. Furthermore, cells established from Fhit knockout tissue showed rapid immortalization and selection of DNA deletions and amplifications, including amplification of the Mdm2 gene, suggesting that Fhit loss-induced genome instability facilitates transformation. We propose that loss of Fhit expression in precancerous lesions is the first step in the initiation of genomic instability, linking alterations at common fragile sites to the origin of genome instability.

Normal cells have robust mechanisms to maintain the proper sequence of their DNA; in cancer cells these mechanisms are compromised, resulting in complex changes in the DNA of tumors. How this genome instability begins has not been defined, except in cases of familial cancers, which often have mutations in genes called “caretaker” genes, necessary to preserve DNA stability. We have defined a mechanism for genome instability in non-familial tumors that occur sporadically in the population. Certain fragile regions of our DNA are more difficult to duplicate during cell division and are prone to breakage. A fragile region, FRA3B, lies within the FHIT gene, and deletions within FRA3B are common in precancer cells, causing loss of Fhit protein expression. We find that loss of Fhit protein causes defective DNA replication, leading to further DNA breaks. Cells that continue DNA replication in the absence of Fhit develop numerous chromosomal aberrations. Importantly, cells established from tissues of mice that are missing Fhit undergo selection for increasing DNA alterations that can promote immortality, a cancer cell hallmark. Thus, loss of Fhit expression in precancer cells is the first step in the initiation of genomic instability and facilitates cancer development.

Metaplastic Carcinoma of the Breast With Dominant Squamous and Sebaceous Differentiation in the Primary Tumor and Osteochondroid Metaplasia in a Distant Metastasis

Metaplastic breast carcinoma is an uncommon tumor that develops from conventional ductal mammary carcinoma, usually consisting of squamous and/or spindle cell components and/or mesenchymal elements. Although several morphological subtypes of metaplastic breast carcinoma are known, sebaceous metaplasia has not yet been described in this context. The authors report a case of an 84-year-old woman with a huge, ulcerated primary tumor in her left breast that had already been present for 10 years. Pulmonary and bone metastases and a tumor nodule in the contralateral breast were also detected at the time of admission. Left simple mastectomy was performed. Histological examination of the tumor revealed metaplastic carcinoma consisting of ductal carcinoma, which immunohistochemically exhibited a triple-negative immunoprofile, along with dominant areas of squamous and sebaceous differentiation. Adjuvant chemotherapy was subsequently given with partial regression of the systemic metastases. Seven months after surgery and diagnosis, a new, rapidly growing, large soft tissue metastatic tumor appeared in the intramuscular compartment of the patient’s right thigh, which was removed and histologically examined. Morphologically this metastatic tumor showed ductal adenocarcinoma along with areas of sebaceous differentiation and, in addition, osteochondroid metaplasia. Immunohistochemically, unlike the primary, this tumor expressed HER-2. The case is presented because of its rarity, and sebaceous differentiation is also proposed as a novel type of metaplasia in this context, expanding the spectrum of the histological patterns of metaplastic breast carcinoma. The literature concerning breast sebaceous lesions is reviewed, and the hypothetical biological mechanisms responsible for the tumor pathogenesis in this case are discussed.

Endometrial cancer as a familial tumor: pathology and molecular carcinogenesis (review)

Some cases of endometrial cancer are associated with a familial tumor and are referred to as hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome). Such tumors are thought to be induced by germline mutation of the DNA mismatch repair (MMR) gene, but many aspects of the pathology of familial endometrial cancer are unclear and no effective screening method has been established. However, the pathology of endometrial cancer with familial tumor has been progressively clarified in recent studies. At present, about 0.5% of all cases of endometrial cancers meet the clinical diagnostic criteria for HNPCC. A recent analysis of the three MMR genes (hMLH1, hMSH2 and hMSH6) revealed germline mutations in 18 of 120 cases (15.0%) of endometrial cancer with familial accumulation of cancer or double cancer, with a frameshift mutation of the hMSH6 gene being the most common. Many cases with mutation did not meet the current clinical diagnostic criteria for HNPCC, indicating that familial endometrial cancer is often not diagnosed as HNPCC. The results suggest that the hMSH6 gene mutation may be important in carcinogenesis in endometrial cancer and germline mutations of the MMR gene may be more prevalent in cases associated with familial accumulation of cancer. An international large-scale muticenter study is required to obtain further information about the pathology of endometrial cancer as a familial tumor.

Lower gastrointestinal tract cancer predisposition syndromes

Although inherited predisposition to colorectal cancer (CRC) has been suspected for more than 100 years, definitive proof of Mendelian syndromes had to await maturation of molecular genetic technologies. Since the l980s, the genetics of several clinically distinct entities has been revealed. Five disorders that share a hereditary predisposition to CRC are reviewed in this article.

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.

Hereditary colon cancer: lynch syndrome

Lynch syndrome is the most common familial colorectal cancer syndrome. It is linked to germline mutations in one of four DNA mismatch repair (MMR) genes. A comprehensive family history is one important way to identify at-risk individuals. The elucidation of the molecular genetics of this syndrome has made it possible to screen for the disorder with molecular tests. Microsatellite instability and/or immunohistochemistry followed by germline testing for mutations in MMR genes is now a standard approach for clinically suspected cases. Correctly recognizing Lynch syndrome is essential for the application of appropriate screening and surveillance measures. Close surveillance and risk-reducing operations can decrease cancer-related mortality. In addition, counseling is an important component of the management of any family with Lynch syndrome.