S1-Guideline Sebaceous Carcinoma.

Sebaceous gland carcinomas are rare malignant cutaneous adnexal tumors with sebocytic differentiation. The typical predilection area is the head and neck region, where sebaceous gland carcinomas are the most common malignant adnexal tumors of the skin. According to their localization a distinction is made between periocular and extraocular sebaceous gland carcinomas. Muir-Torre syndrome (MTS) should always be ruled out if it is suspected. In terms of prognosis, sebaceous gland carcinomas are potentially aggressive tumors with a clear tendency to recur and metastasize. Only small extraocular sebaceous gland carcinomas that have been completely resected have a very good prognosis. Sebaceous gland carcinomas most frequently metastasize lymphogenously to regional or distant lymph nodes; organ metastasis occurs less frequently. Periocular sebaceous gland carcinomas have a higher metastasis rate (up to 15%) than extraocular sebaceous gland carcinomas (up to 2%). Complete micrographically controlled surgery (MCS) of the primary tumor is the therapy of first choice, regardless of periocular or extraocular localization. Adjuvant or therapeutic radiotherapy may be considered. There is currently no established standard therapy for advanced, inoperable, or metastatic sebaceous gland carcinomas. Local procedures and systemic therapies such as chemotherapy or immunotherapy can be considered. The procedure should be determined individually by an interdisciplinary tumor board. Close follow-up care is recommended for these potentially aggressive carcinomas.

Mosaic Muir Torre Syndrome: Keratoacanthoma as a Piece of the Puzzle.

ABSTRACT: Lynch syndrome is an inherited condition, which increases the risk of numerous visceral malignancies and cutaneous tumors such as keratoacanthomas and sebaceous tumors. It is typically identified by immunohistochemistry of tissue taken from tumors or through genetic testing with next-generation sequencing. Diagnosing Lynch syndrome becomes more complex when the individual is mosaic for the relevant pathogenic variant. There are very few cases of this reported in the medical literature. It is even more unusual for the diagnosis to be made based on testing of a keratoacanthoma lesion. We report a case where immunohistochemistry of a keratoacanthoma helped make a diagnosis of mosaic Lynch syndrome. We will explore how mosaicism should be considered when a phenotype is strong, even if next-generation sequencing reports no pathogenic or likely pathogenic variant and how lesions such as keratoacanthomas can have a role in the early detection and treatment of future malignancies.

Immunohistochemistry, Molecular Biology, and Clinical Scoring for the Detection of Muir-Torre Syndrome in Cutaneous Sebaceous Tumors: Which Strategy?

BACKGROUND: Sebaceous neoplasms (SNs) always raise the possibility of an association with Muir-Torre syndrome (MTS) and permit to screen internal malignancies, colorectal and endometrial carcinomas, before they become symptomatic. Immunohistochemistry (IHC), molecular biology, and clinical examination are different approaches for detection of MTS. We conducted a retrospective analysis of non-selected SNs in order to determine the optimal tools to implement for MTS screening. METHODS: Deficient MMR phenotype (dMMR) was determined by either IHC using antibodies directed to four mismatch repair (MMR) antigens on tissue microarray or molecular biology using pentaplex PCR. The Mayo Clinic risk score of MTS was calculated from medical records. Sensibility and specificity of each test for the detection of MTS were determined. RESULTS: We included 107 patients, 8 with multiple SNs, for a total of 123 SNs (43 sebaceous adenomas, 19 sebaceomas, and 61 sebaceous carcinomas (SC)). Loss of at least one MMR protein was observed in 70.7% of tumors, while 48% had a microsatellite instable phenotype. Concordance between both techniques was 92.9%, with a 0.85 Cohen's kappa coefficient. Nineteen patients (20.2%) had a ≥2 points Mayo Clinic risk score, one having a pMMR SC. Among the 13 patients with confirmed MTS, 2 had a low Mayo Clinic risk score (1 point). IHC had the highest sensitivity for MTS screening (100%) with a specificity of 34.1%, while a >2-point Mayo Clinic risk score had a lower sensitivity (92%) but a higher specificity (89%). CONCLUSION: To detect MTS in SN patients, the first-line Mayo Clinic risk score followed by IHC appears to be the most accurate strategy with lower cost for society. This strategy should be adapted to the medico-economic resources of each country.

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

BACKGROUND: Muir-Torre syndrome (MTS) is a rare genetic disorder that is caused by mismatch repair (MMR) protein mutations. MTS increases the risk of developing skin and gastrointestinal tumors such as sebaceous adenomas (SAs), sebaceous carcinomas, colorectal cancer, endometrial cancer, and ovarian cancer. The risk of developing these types of tumors varies depending on the involved mutation and the individual's family history risk. CASE PRESENTATION: A 47-year-old male presented with multiple skin lesions on the scalp, face, flank, and back. The examination revealed well-circumscribed, dome-shaped papules with a yellowish appearance with white oily material in the center. Histopathologic examination showed a well-circumscribed sebaceous neoplasm consistent with a mixture of basaloid cells and lobules of bland-appearing mature adipocytes that communicate directly to the surface epithelium. Focal cystic changes and peritumoral lymphocytic infiltrate were noted. Increased mitotic figures were seen in the basaloid cell component. The overall findings were consistent with the diagnosis of SAs. MMR staining showed preserved expression in MLH1 and PMS2 proteins, while MSH2 and MSH6 staining showed loss of protein expression. A screening colonoscopy showed numerous colon and rectal tumors, prompting concerns about the likelihood of MTS. Surgical intervention was pursued for complete resection. Histology revealed a diagnosis of mucinous adenocarcinoma/adenocarcinoma with mucinous features of the colon. The diagnosis of MTS was supported by molecular testing that revealed MSH2 germline mutation. The increased likelihood of MTS was attributed to the occurrence of SAs in unusual locations of the head and neck regions, unlike typical cases. CONCLUSION: MTS is a rare clinical condition that necessitates prompt thorough evaluation and periodic surveillance. When SA is encountered in atypical locations, it is important to consider additional testing supported by immunohistochemical staining, molecular testing, and regular screening to exclude the likelihood of MTS.

Sebaceous carcinoma epidemiology, associated malignancies and Lynch/Muir-Torre syndrome screening in England from 2008 to 2018.

BACKGROUND: Sebaceous carcinomas (SC) may be associated with the cancer predisposition syndrome Muir-Torre/Lynch syndrome (MTS/LS), identifiable by SC mismatch repair (MMR) screening; however, there is limited data on MMR status of SC. OBJECTIVE: To describe the epidemiology of SC, copresentation of other cancers, and population level frequency of MMR screening in SC. METHODS: A population-based retrospective cohort study of SC patients in the National Cancer Registration and Analysis Service in England. RESULTS: This study included 1077 SC cases (739 extraocular, 338 periocular). Age-standardized incidence rates (ASIR) were higher in men compared with women, 2.74 (95% CI, 2.52-9.69) per 1,000,000 person-years for men versus 1.47 person-years (95% CI, 1.4-1.62) for women. Of the patients, 19% (210/1077) developed at least one MTS/LS-associated malignancy. MMR immunohistochemical screening was performed in only 20% (220/1077) of SC tumors; of these, 32% (70/219) of tumors were MMR deficient. LIMITATIONS: Retrospective design. CONCLUSIONS: Incorporation of MMR screening into clinical practice guidelines for the management of SC will increase the opportunity for MTS/LS diagnoses, with implications for cancer surveillance, chemoprevention with aspirin, and immunotherapy treatment targeted to MTS/LS cancers.

Comparison of clinicopathologic features, survival, and demographics in sebaceous carcinoma patients with and without Muir-Torre syndrome.

BACKGROUND: Visceral malignancies in patients with Lynch syndrome behave less aggressively than in those without Lynch syndrome. The behavior of sebaceous carcinoma (SC) in Muir-Torre syndrome (MTS), a variant of Lynch syndrome, is incompletely investigated. OBJECTIVE: To investigate features and survival of SC patients with and without MTS. METHODS: Retrospective cohort study in the Surveillance, Epidemiology, and End Results 17 database from 2000 to 2019 of patients with SC. Patients were classified as MTS or non-MTS cases based on a threshold score of 2 on the Mayo MTS risk score. RESULTS: We identified 105 (2.8%) MTS cases and 3677 (97.2%) non-MTS cases. On univariate analysis, MTS patients were younger, had a higher proportion of tumors outside the head/neck, and had fewer high-grade tumors. On Kaplan-Meier analysis, MTS patients trended toward having better SC-specific survival. On multivariate Cox proportional hazards analysis adjusting for other covariates, MTS status was an independent predictor of worse overall survival. However, there was no association between MTS status and SC-specific survival. LIMITATIONS: Given relatively high disease-specific survival in SC, our study may have been underpowered to detect a difference on Kaplan-Meier analysis. CONCLUSIONS: Our study suggests SC does not behave more aggressively in patients with MTS.

Muir-Torre Syndrome: A Cutaneous Finding Amidst Broader Malignancies.

Muir-Torre syndrome (MTS) is a rare autosomal dominant genetic condition resulting from microsatellite instability which is caused by mutations in DNA mismatch repair genes. This disorder predisposes individuals to skin tumors and visceral malignancies and may be precipitated in immunocompromised or transplant patients. MTS requires close cancer surveillance for the patient and family because of the tendency to develop aggressive internal malignancies and sebaceous carcinoma. Immunohistochemistry and or genetic testing can confirm the diagnosis of MTS. This review offers an update to the guidelines, diagnosis, and management of MTS while offering a unique perspective on an important but lesser-known syndrome.

Muir-Torre Syndrome with Novel Mutation in the MSH2 Gene.

Muir-Torre syndrome (MST) is a rare autosomal dominant subtype of hereditary non-polyposis colorectal carcinoma. The diagnosis is established based on the coexistence of sebaceous gland tumors and visceral organ malignancies. Mutations in the mismatch repair genes are responsible for Muir-Torre syndrome. Internal malignancies seen in MTS are most commonly colorectal, gastrointestinal system, endometrial, genitourinary system, breast, lung, brain, and hepatobiliary system malignancies. Detection of sebaceous neoplasia is essential in investigating Muir-Torre syndrome, allowing early detection of internal malignancies. Herein, we present the case of a patient with sebaceous adenomas, internal malignancies, and a new mutation detected during the genetic examination.

Muir-Torre syndrome: a case of unusual coexisting genetic mutations.

Patients with Muir-Torre syndrome (MTS) commonly have germline mismatch repair mutations in MLH1, MSH2 or MSH6, with a strong predominance in MSH2. A subset of approximately one-third of patients will instead have an autosomal recessive base excision repair mutation in MUTYH called MUTYH polyposis. To the best of our knowledge, this is the first report of coexisting germline MSH2 and MUTYH mutations in a patient with MTS.

Keratoacanthoma or cutaneous squamous cell carcinoma revealing a DNA mismatch repair default (Muir-Torre Syndrome).

Keratoacanthoma (KA) and well-differentiated cutaneous squamous cell carcinoma (cSCC) are hardly distinguishable clinically and histologically. They both can be seen in patients with hereditary non-polyposis colorectal cancer (HNPCC) or Lynch Syndrome, corresponding to DNA microsatellite instability. In our case, a young man had the excision of two rapidly growing skin tumours for which distinction between KA and cSCC was initially clinically and pathologically challenging. The diagnosis of well-differentiated cSCCs was made and the patient was treated with surgery. Ten years after the first cSCC, he was diagnosed with Muir-Torre syndrome, a variant of Lynch syndrome, with an heterozygote mutation of the MSH2 gene. This later diagnosis allowed to screen his family members for the same mutation and to adopt an appropriate follow-up regarding the risk of digestive tumours for him and his family. Furthermore, it is important to know that, in case of non-resectable cSCC occurring in this patient, immunotherapy using anti-PD1 antibody would probably be effective due to the known increased immunogenicity of MMR deficient tumours.

In Vivo Reflectance Confocal Microscopy of Adnexal Tumors: Evaluation of Trichoepithelioma, Sebaceoma, and Fibrofolliculoma.

ABSTRACT: Cutaneous adnexal tumors are benign and malignant neoplasms that undergo morphological differentiation into cutaneous adnexa, comprising pilosebaceous, eccrine, or apocrine units. Reflectance confocal microscopy is a noninvasive diagnostic method that enables in vivo visualization of tissues at a similar resolution as conventional histopathology. The use of this method in skin imaging over the past several years has improved dermatological diagnoses, potentiating its wide application, especially for benign and malignant skin tumors. We describe the use of reflectance confocal microscopy in cases of trichoepithelioma, sebaceoma, and fibrofolliculoma and correlate the resulting clinical, histopathological, and confocal microscopy images.

Sebaceous adenoma of the conjunctiva and caruncle: a clinicopathological report of three cases and literature review.

Sebaceous tumors of the conjunctiva and caruncle are rare conditions, accounting for 1% of caruncle lesions and even lower among conjunctival lesions. Almost 50% of cases are associated with Muir-Torre syndrome, a rare autosomal-dominant condition characterized by at least one sebaceous skin tumor and one visceral malignancy. We report 3 cases of sebaceous adenoma with different presentations that were submitted to excisional biopsy and immunohistochemical study. Diagnosis of these tumors should increase the level of suspicion and lead to clinical investigation to rule out neoplasms, particularly because in up to 41% of cases, these can be the first sign of the disease.

Seborrheic Keratosis With Sebaceous Differentiation, a Series of 8 Cases and Critical Review of the Literature.

ABSTRACT: Seborrheic keratosis with sebaceous differentiation (SKSD) can sometimes raise uncertainty, confuse with other even malignant entities, and lead to overestimation of this harmless variant. Retrospective analysis of the cases diagnosed as SKSD and a search of the pertaining literature were conducted. Eight cases of SKSD were found. Histologically, these lesions show a flat to plate-like outgrowth of basaloid cells with solitary or clustered sebocytes at the bottom of the rete ridges and variable sebaceous ducts with luminal cuticula. The lesions differed in the outgrowth subpattern: flat/macular, acanthotic, or reticulated. No association was found with Muir-Torre syndrome, and no malignant transformation was seen in these lesions. Literature search revealed confusingly designated lesions that simply represented SKSD. SKSD can show several growth patterns as classic SK. This entity is either underreported or even underrecognized. This entity is benign; however, according to the literature, exclusion of an associating Muir-Torre syndrome should be warranted. The published literature about this lesion is confusing and inconsistent. We suggest the avoidance of confusing terminology and particularly the terminus epithelioma for such lesions.

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 with a keratoacanthoma and sebaceous neoplasms: Clinicopathological features and a speculation on the pathogenesis of cutaneous tumor type.

Muir-Torre syndrome is a hereditary condition characterized by occurrence of sebaceous neoplasms or keratoacanthomas and visceral tumors. The most common mechanism for this syndrome is a constitutional defect in the mismatch repair genes. We report the case of a 67-year-old woman with a mutator L homologue 1 (MLH1) mutation. She had a history of endometrial and colorectal cancers. The patient presented with a typical keratoacanthoma on the right cheek and numerous sebaceous neoplasms on the face and trunk. Seven sebaceous adenomas and a low-grade sebaceous carcinoma were excised. Most sebaceous adenomas showed dermoscopic features such as some yellow comedo-like globules and curved vessels in creamy-white areas. Moreover, they revealed pathological features such as keratoacanthoma-like architecture and peritumoral or intratumoral lymphocytes. One of these sebaceous adenomas indicated histopathologically spontaneous regression and another was continuous with the hair follicle. Immunohistochemical staining for mismatch repair proteins revealed loss of expression for MLH1 and postmeiotic segregation increased 2 (PMS2) proteins in tumor cells nuclei in both keratoacanthoma and sebaceous adenoma. Nuclei in overhanging epithelial lips of the keratoacanthoma were also negative. These findings suggest that the type of Muir-Torre syndrome-related cutaneous tumor may have been affected by mismatch repair protein deficient sites in the pilosebaceous unit.

The DNA mismatch repair system in sebaceous tumors: an update on the genetics and workup of Muir-Torre syndrome.

Mutations in the genes encoding the DNA mismatch repair (MMR) are identified in most sebaceous neoplasms. Sebaceous tumors are rare in the general population; however, they are common in patients with inherited or acquired mutations in the MMR system. This article describes the DNA MMR system and its implication in sebaceous tumors as well as discusses the recent recommendations for screening for Muir-Torre syndrome (MTS) in patients presenting with sebaceous tumors.

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

Importance: Appropriate use criteria for Muir-Torre syndrome (MTS) screening suggest that mismatch repair protein (MMRP) immunohistochemical (IHC) testing is usually appropriate in patients with 2 or more sebaceous neoplasms (SNs). While MTS is known to be caused by a germline mutation in mismatch repair genes, data are limited as to whether individual sebaceous tumors in these patients with multiple lesions show identical MMRP IHC staining patterns. Objective: To determine concordance of MMRP IHC staining patterns in lesions of patients with MTS who have multiple SNs. Design, Setting, and Participants: This retrospective single-center case series evaluated 38 SNs in 11 patients with MTS confirmed by genetic testing for MMRP IHC staining patterns. Tumor sites were classified as either facial or extrafacial. Data were collected between January 1, 2007, and January 1, 2018. Main Outcomes and Measures: In each patient, MMRP IHC staining patterns for SNs were compared with one another to evaluate intrapatient concordance between lesions, and to the patient's known germline mutation. Results: A total of 11 patients (7 women and 4 men) with MTS, with a mean (SD) age of 59.3 (10.6) years at time of SN biopsy, were identified. There was high concordance between MMRP IHC staining results (2-4 lesions per patient) and the patient's mutation status, with 36 of 38 total lesions (95%) matching (sensitivity, 94.7%; 95% CI, 82.3%-99.4%). Extrafacial site tumors represented 16 of 38 total lesions (42%) and demonstrated 100% concordance of IHC results to germline mutation. Only 1 of 11 patients (9%) demonstrated discordant results, with both lesions in this patient occurring on a facial site. Conclusions and Relevance: In patients with known MTS, SNs present with highly concordant MMRP IHC staining profiles across multiple lesions. There is also a strong association with underlying germline mutations. A diagnosis of MTS might be supported by MMRP IHC when the pretest probability is high.

Muir-Torre Syndrome.

A 64-year-old man was referred to our dermatology clinic with a diagnosis of Muir-Torre syndrome (MTS), he had a history of multiple sebaceous carcinomas and sebaceous adenomas removed over the years. The patient has also had visceral cancer and had undergone a colon resection 17 years before to treat colon cancer and was recently diagnosed with invasive high-grade urothelial carcinoma of the right ureter. In addition, the patient has an extensive family history of cancer; a pedigree was constructed to document this history (Figure 1). Of note is that the patient's mother and father were second cousins. The patient's father was diagnosed with lung cancer at age 57 and died of colon cancer at the age of 72. The patient's mother died of colon cancer at age 74. The patient has three siblings: a sister and two brothers. The sister died of bone cancer at age 42. One brother had a number of cancers including colon, kidney, and skin cancers and died at age 53. His other brother is alive and has a history of colon cancer, kidney cancer, and ureteral cancer. The patient has five children. He has a 40-year-old son who, at the age of 30, was diagnosed with testicular cancer. His daughters are 47, 44, 39, and 34, with no history of malignancy to date. The patient had three maternal aunts, all of whom succumbed to colon cancer, as well as two paternal uncles who died of lung cancer. The patient's maternal grandfather was a smoker and he also died of lung cancer.