Colon tumor
Familial polyposis syndromes
Muir-Torre syndrome

Author: Jennifer Findeis-Hosey, M.D. (see Authors page)
Editorial board Review: Raul Gonzalez, M.D.

Revised: 26 August 2015, last major update August 2015

Copyright: (c) 2002-2015, PathologyOutlines.com, Inc.

PubMed Search: Muir-Torre syndrome [title] colon
Definition / General
  • Clinical variant of Lynch syndrome with cutaneous sebaceous neoplasms (including sebaceous adenoma, sebaceoma and sebaceous carcinoma) or keratoacanthomas in addition to visceral malignancies of Lynch syndrome
  • Terminology
  • Also called Torre-Muir syndrome
  • Epidemiology
  • Sebaceous neoplasms present at mean age of 53 years
  • Male predominance (3:2)
  • Sites
  • Sebaceous tumors are most common below the neck
  • Colorectal tumors are more commonly located in proximal colon
  • Etiology
  • Typically due to germline mutations in a DNA mismatch repair gene: most commonly MSH2 (60-90%); may be due to mutation in MLH1 or MSH6
  • May also be due to inactivation through hypermethylation of a DNA mismatch repair gene
  • Clinical Features
  • Skin neoplasm may be presenting lesion 22% of time (J Am Acad Dermatol 1999;41:681)
  • Colorectal adenocarcinoma is prototypical tumor of Lynch Syndrome (typically proximal colon); however, patients may develop other low grade carcinomas, including endometrial carcinomas (15%) and genitourinary carcinomas
  • Diagnosis
  • Clinical algorithms include Amsterdam criteria and Revised Bethesda criteria
  • Mayo Muir-Torre syndrome risk scoring system assesses whether patients with sebaceous neoplasms are in need of further evaluation for Lynch Syndrome (Genet Med 2014;16:711)
  • Can screen using immunohistochemical testing for loss of mismatch repair protein expression (MLH1, MSH2, MSH6, PMS2) and/or microsatellite instability testing via PCR
  • Germline genetic testing
  • Prognostic Factors
  • Muir-Torre associated neoplasms tend to be less aggressive than the same tumors in non-syndromic patients
  • Case Reports
  • 58 year old man with retroperitoneal undifferentiated pleomorphic sarcoma associated with Muir-Torre syndrome (J Cutan Pathol 2013;40:730)
  • Unusual case of hepatocellular carcinoma in non-cirrhotic background in Muir-Torre patient (Fam Cancer 2012;11:7)
  • Sebaceous adenoma arising within an ovarian mature cystic teratoma in Muir-Torre syndrome (Ann Diagn Pathol 2012;16:485)
  • Micro Description
  • Cutaneous tumors demonstrate sebaceous origin or differentiation, including coarsely vacuolated cytoplasm and starry nuclei (mulberry cells) (Arch Pathol Lab Med 2014;138:1685)
  • Muir-Torre syndrome associated sebaceous tumors are often nodulocystic
  • Cystic sebaceous neoplasms have only been reported in patients with Muir-Torre syndrome
  • Colorectal adenocarcinomas tend to have mucinous features, with tumor infiltrating lymphocytes and Crohn-like reaction
  • Micro Images
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    MSH2+

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    Significant loss of MSH6

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    Colon adenoma and colonic mucosa

    Positive Stains
  • EMA in sebaceous neoplasms
  • Negative Stains
  • Loss of MSH2 and MSH6 staining in colonic polyps (Arch Dermatol 2006;142:1039)
  • CK15 and MSH2 in sebaceous neoplasms (J Cutan Pathol 2006;33:634, Dermatol Online J 2006;12:4, Am J Clin Dermatol 2007;8:315)
  • Molecular / Cytogenetics Description
  • Autosomal dominant inheritance
  • Mutations most commonly in MLH1 or MSH2 mismatch repair genes (3p22.2 and 2p21, respectively)
  • Microsatellite instability is present in approximately 70% of Muir-Torre syndrome associated tumors
  • Germline testing confirms the diagnosis
  • Differential Diagnosis
  • Lynch syndrome: similar presentation and genetics, except no sebaceous neoplasms