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.

A tumor focused approach to resolving the etiology of DNA mismatch repair deficient tumors classified as suspected Lynch syndrome

Routine screening of tumors for DNA mismatch repair (MMR) deficiency (dMMR) in colorectal (CRC), endometrial (EC) and sebaceous skin (SST) tumors leads to a significant proportion of unresolved cases classified as suspected Lynch syndrome (SLS). SLS cases (n=135) were recruited from Family Cancer Clinics across Australia and New Zealand. Targeted panel sequencing was performed on tumor (n=137; 80xCRCs, 33xECs and 24xSSTs) and matched blood-derived DNA to assess for microsatellite instability status, tumor mutation burden, COSMIC tumor mutational signatures and to identify germline and somatic MMR gene variants. MMR immunohistochemistry (IHC) and MLH1 promoter methylation were repeated. In total, 86.9% of the 137 SLS tumors could be resolved into established subtypes. For 22.6% of these resolved SLS cases, primary MLH1 epimutations (2.2%) as well as previously undetected germline MMR pathogenic variants (1.5%), tumor MLH1 methylation (13.1%) or false positive dMMR IHC (5.8%) results were identified. Double somatic MMR gene mutations were the major cause of dMMR identified across each tumor type (73.9% of resolved cases, 64.2% overall, 70% of CRC, 45.5% of ECs and 70.8% of SSTs). The unresolved SLS tumors (13.1%) comprised tumors with only a single somatic (7.3%) or no somatic (5.8%) MMR gene mutations. A tumor-focused testing approach reclassified 86.9% of SLS into Lynch syndrome, sporadic dMMR or MMR-proficient cases. These findings support the incorporation of tumor sequencing and alternate MLH1 methylation assays into clinical diagnostics to reduce the number of SLS patients and provide more appropriate surveillance and screening recommendations.

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

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

Muir-Torre Syndrome: Abdominal Sebaceous Carcinoma

A 56-year-old male with a past medical history of arachnoid cysts and with two previous brain operations and a ventriculoperitoneal shunt presented with a large left lower quadrant (LLQ) abdominal mass for one year, growing rapidly for the past three months. He endorsed pus and blood leaking from ulceration on the lateral underside of the mass, and a section of the mass ruptured with blood and pus draining out on the day of admission. He denied any fevers, chills, pain, or numbness in the mass or any history of similar masses. Of note, the patient has an extensive familial history of cancer including colorectal cancer in his mother in her 30s. Computed tomography and biopsy of mass were concerning for malignancy, reporting a neoplasm in the dermis that grows in round and irregular lobules of cells along with the majority of the cells having oval nuclei with areas of sebaceous differentiation. Pathology showed sebaceous carcinoma with concern for Muir-Torre syndrome. The patient was discharged and instructed to follow up with oncology and gastroenterology.

Basal Cell Carcinoma and Sebaceoma Within Nevus Sebaceous of the Scalp

This case describes the occurrence of basal cell carcinoma (BCC) and sebaceoma within a nevus sebaceous (NV), which has not yet been previously reported. This is significant to dermatologists as it emphasizes the importance of close monitoring of benign sebaceous nevi in the event that malignant transformation occurs, although such occurrences are rare. Prompt consideration for prophylactic excision of NS is warranted prior to malignant transformation. 

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.

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.

Cutaneous Squamous Cell Carcinoma in Lynch Syndrome - An Overlooked Association

Lynch syndrome is an autosomal dominant disorder caused by germline mutation affecting mismatch-repair genes. Genetic testing is performed selectively. Diagnosed individuals are to undergo surveillance to detect and manage Lynch syndrome-related cancers early in the course.

Muir-Torre syndrome is a phenotypic variant of Lynch syndrome characterized by sebaceous neoplasms, keratoacanthoma, or both in addition to other Lynch syndrome-related cancers. Other neoplasms of the skin, such as squamous cell carcinoma, are not recognized as part of the Lynch syndrome tumor-spectrum. We report a case of cutaneous squamous cell carcinoma occurring in a patient with Lynch syndrome and explore some of the characteristic features and significance of this association.

MSH-2 and MLH-1 protein expression in Muir Torre syndrome-related and sporadic sebaceous neoplasms

BACKGROUND

Muir-Torre Syndrome (MTS) is a rare autosomal-dominant disorder characterized by the predisposition to both sebaceous neoplasm and internal malignancies. MTS-associated sebaceous neoplasms reveal mutations in DNA mismatch repair (MMR) genes and microsatellite instability. A significant part of MTS patients represents a phenotypic variant, the hereditary nonpolyposis colorectal cancer (HNPCC). A strong correlation between microsatellite instability and immunostaining has been demonstrated. The early recognition of sebaceous neoplasm as part of MTS, and their differentiation from sporadic sebaceous neoplasm may have an important application in a clinical setting. The absence of MLH-1 or MSH-2 expression by immunostaining identifies tumors with mismatch repair deficiency.

OBJECTIVES

Our aim is to determine whether an immunohistochemical approach, targeting DNA repair proteins MSH-2 and MLH-1 in MTS-related sebaceous neoplasm and their sporadic counterparts, can be used for their identification.

METHODS

We examined 15 sebaceous neoplasms (including 6 internal malignancy- associated sebaceous neoplasms and 8 sporadic sebaceous neoplasms) from 11 patients for the expression of MSH-2 and MLH-1 by immunohistochemistry.

RESULTS

Four of 5 internal malignancy-associated sebaceous neoplasms showed loss of expression of MSH-2 or MLH-1. Correlation of the immunostaining pattern of the sebaceous neoplasms and the patients' positive history of colon carcinoma was 80%. Seven of 8 sporadic sebaceous neoplasms showed a positive expression of MSH-2 and MLH-1. The prevalence for loss of expression of MMR proteins in sebaceous neoplasms was 38.5%. MMR immunostaining had 87.5% specificity and 80% sensitivity.

LIMITATIONS

This study is limited by a small sample size, and by bias selection due to the use of non nationwide data-base as the resource of cases.

CONCLUSIONS

Our findings demonstrate that immunohistochemical testing for internal malignancy-associated sebaceous neoplasms is a practical approach to confirm a suspected inherited MMR gene defect, and an accurate method to distinguish between sporadic and MTS-associated sebaceous lesions.