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Muir-Torre syndrome


Other Names for this Disease
  • Cutaneous sebaceous neoplasms and keratoacanthomas multiple with gastrointestinal and other carcinomas
  • Keratoacanthoma
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Your Question

I have a patient with Muir-Torre syndrome. Can you provide me with information related to this condition?

Our Answer

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What is Muir-Torre syndrome?

Muir-Torre syndrome is an autosomal dominant skin condition of genetic origin, characterized by tumors of the sebaceous gland or keratoacanthoma that are associated with visceral malignant diseases (cancers of the internal organs). The cutaneous characteristics of Muir-Torre syndrome are sebaceous adenoma, sebaceous epithelioma, sebaceous carcinoma, or multiple keratoacanthomas, whereas visceral malignant diseases include colorectal, endometrial, urological, and upper gastrointestinal tumors. Men are affected twice as often as women.[1][2] Muir-Torre syndrome is associated with hereditary non-polyposis colon cancer (HNPCC), an autosomal dominant cancer genetic syndrome. Sebaceous neoplasms associated with Muir-Torre syndrome exhibit microsatellite instability (MSI), as do other HNPCC-related cancers.[3][4]
Last updated: 6/2/2011

What are the common findings among patients with Muir-Torre syndrome?

Sebaceous adenoma is the most characteristic marker of Muir-Torre syndrome. Other types of skin tumors commonly identified in these individuals are sebaceous epitheliomas, sebaceous carcinomas and keratoacanthomasSquamous cell carcinoma and multiple follicular cysts are sometimes included in the cutaneous tumors. The skin lesions may precede the presentation of internal malignancy, although they often develop later.[4]

The most common visceral neoplasm in Muir-Torre syndrome is colorectal cancer, occurring in almost one half of patients. The second most common site is the genitourinary tract, representing approximately one quarter of visceral cancers. A wide variety of other cancers, including breast cancer, lymphoma and rarely leukemia, salivary gland tumors, lower and upper respiratory tract tumors, and chondrosarcoma, are reported. Intestinal polyps occur in at least one quarter of patients. Other benign tumors described in Muir-Torre syndrome include ovarian granulosa cell tumor, hepatic angioma, benign schwannoma of the small bowel, and uterine leiomyomas.[4]

Last updated: 6/2/2011

What causes Muir-Torre syndrome?

Muir-Torre syndrome is considered a subtype of the more common hereditary nonpolyposis colorectal cancer syndrome (HNPCC). This condition is associated with an inherited defect in one copy of a DNA mismatch repair gene (MMR), which eventually leads to microsatellite instability (MSI). The 2 major MMR genes involved are MLH1 and MSH2. Approximately 70% of tumors associated with the Muir-Torre syndrome have MSI. While germline disruption of MLH1 and MSH2 is evenly distributed in HNPCC, disruption of MSH2 is seen in greater than 90% of Muir-Torre syndrome patients.[3][4]
Last updated: 6/2/2011

How is Muir-Torre syndrome diagnosed?

Clinically, a diagnosis of Muir-Torre syndrome is made by the presence of at least one sebaceous gland tumor (adenoma, epithelioma, carcinoma, cystic sebaceous tumor, or keratoacanthoma with sebaceous differentiation) associated with at least one primary visceral malignancy. Alternatively, diagnosis of Muir-Torre syndrome can be made if the patient has multiple keratoacanthomas with multiple internal malignancies and a family history of Muir-Torre syndrome.[5] 

Muir-Torre syndrome can also be recognized by genetic testing. A high proportion of both benign and malignant skin tumors (as well as internal malignancies) from Muir-Torre syndrome patients show microsatellite instability (MSI) due to germline mutations in either of two DNA mismatch repair (MMR) proteins, MSH2 or MLH1.[3][4][5]

Last updated: 6/2/2011

How is Muir-Torre syndrome inherited?

A positive family history of Muir-Torre syndrome can be found in roughly 50% of patients. The condition is inherited in an autosomal dominant fashion. It shows a high degree of penetrance and variable expression. In autosomal dominant conditions, one needs only one altered gene in order to show symptoms. Children of a Muir-Torre syndrome individual, therefore, may have a 50% risk of inheriting the cancer predisposition.[4]
Last updated: 6/3/2011

What types of evaluations are recommended for individuals at-risk for Muir-Torre syndrome?

Muir-Torre syndrome should be considered in patients initially seen with sebaceous tumors of the eyelid or other sebaceous adenomas. Immunohistochemistry for MSH2 is a practical initial approach to screen for Muir-Torre syndrome in patients with sebaceous tumors.[6]

The following laboratory tests can be of diagnostic value if patients present with cutaneous signs of Muir-Torre syndrome:[4][6]
  • Sigmoidoscopy may be performed for screening of colonic polyposis and colonic carcinoma.
  • Endoscopy may be performed to check for an occult gastric carcinoma.
  • Serum carcinoembryonic antigen values are frequently increased in patients with colonic carcinomas.
  • A complete blood cell count assists in detecting hematologic malignancies.
  • A bone marrow examination may be needed to further delineate a hematologic malignancy.
  • Laryngoscopy with biopsy examination of any suspicious lesions can rule out an occult laryngeal carcinoma.
  • Abdominal CT scanning and MRI assist in detecting an occult internal malignancy, such as kidney and urothelial cancers, in patients with Muir-Torre syndrome.
  • A biopsy of skin tumors performed for histopathologic examination provides an accurate diagnosis of sebaceous neoplasms, including sebaceous adenomas.
  • Histopathologic examination of specimens obtained from polypectomy (removal of individual polyps) and laryngoscopy of patients with suspected Muir-Torre syndrome confirms the presence or the absence of occult internal malignancy.
  • Peripheral blood smear, bone marrow examination, and lymph node biopsy may assist in detecting an associated hematologic malignancy in these patients.
Last updated: 6/3/2011

What is the prognosis for individuals who have been diagnosed with Muir-Torre syndrome?

The skin cancers associated with Muir-Torre syndrome tend to have a nonaggressive course. Despite this, approximately 60% of patients develop metastatic disease. Fatalities due to internal malignancies have been reported. Patients with Muir-Torre syndrome should have regular screening examinations, particularly of the gastrointestinal tract, colorectum, genitourinary tract, and female genital tract.[4]
Last updated: 6/3/2011

References