A Case of Muir-Torre Syndrome

Abstract

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.

Keywords: colon cancer; hnpcc; lynch syndrome; mismatch repair genes; muir-torre syndrome.

Figure 1. Hematoxylin and eosin-stained section of the left upper cheek showing a sebaceous adenoma.

Figure 2. Immunohistochemistry staining of the sebaceous adenoma demonstrating retained expression of PMS2 in 2(a) and loss of MSH6 in the section in (b).

Figure 3. Proposed algorithm for the diagnosis of MTS.

MTS: Muir-Torre syndrome Source: Ponti and Ponz de Leon [6], reprinted with permission