What is Torre-Muir syndrome?
Torre-Muir syndrome is a rare inherited condition in which there are sebaceous (oil gland) skin tumours in association with internal cancer.
The most common organ involved is the gastrointestinal tract, with almost one half of patients having colorectal cancer. The second most common site is cancer of the genitourinary tract.
Torre-Muir syndrome is also known as ‘Muir-Torre syndrome’ and ‘sebaceous neoplasia/visceral carcinoma’.
What is Lynch syndrome?
Lynch syndrome is also known as hereditary non polyposis colorectal cancer (HNPCC). It is a rare genetic (autosomal dominant condition) that gives a predisposition to cancer of the lower gastrointestinal tract (colorectal), uterus (endometrium) and ovary. It is due to an inability to repair damaged DNA.
Research has shown that some families with Lynch syndrome share the same genetic fault as families with Torre-Muir syndrome. Torre-Muir syndrome may be part of the Lynch syndrome.
Cutaneous features of Torre-Muir syndrome
Skin lesions may occur before or after the diagnosis of the internal cancer. Sebaceous tumours are generally otherwise rare and their development should arouse suspicion of Torre-Muir syndrome and the need for more investigative tests. The sebaceous neoplasms include:
- sebaceous adenomas
- sebaceous epitheliomas
- sebaceous carcinomas.
Other skin lesions that may arise in affected family members include:
|Cutaneous sebaceous neoplasm||Features|
|Sebaceous adenoma and sebaceous epithelioma||
What is the cause of Torre-Muir syndrome?
Torre-Muir syndrome is an autosomal dominant condition meaning half of an affected person's children also have the syndrome. It is due to a genetic mutation.
Mutations in 4 mismatch repair genes have been found in Lynch syndrome or hereditary nonpolyposis colorectal cancer syndrome. These mostly involving the MSH2 gene, located on chromosome 2p. It is likely that Torre-Muir syndrome is associated with mutations of these genes.
How is it diagnosed?
Torre-Muir syndrome is usually suspected because of the clinical features. However, if a sebaceous adenoma, a sebaceous carcinoma or colonic polyp is removed surgically, the pathologist may examine the cells to see whether the MSH gene products have microsatellite instability, a characteristic of the syndrome.
What is the treatment for Torre-Muir syndrome?
Patients with Torre-Muir syndrome need to undergo medical and physical examinations and appropriate laboratory and radiographic tests on a regular basis to check for internal malignancies, particularly of the gastrointestinal and genitourinary tracts. Patients need regular colonoscopy for early detection of colorectal tumours. Cancers should be managed with appropriate anti-cancer therapies.
In some families genetic diagnosis can identify asymptomatic carriers of the mutation. All first-degree relatives, especially mutation carriers, should be referred from the age of 20 years for routine follow-up and early treatment
Treatment of the skin lesions includes:
- Benign tumours and keratoacanthomas may be treated surgically with excision or cryotherapy
- Sebaceous carcinomas should be excised completely
- Oral retinoids, e.g. acitretin or isotretinoin, may prevent some lesions
- Interferon injections are sometimes combined with retinoid treatment
Improvement of Torre-Muir syndrome has been noted in patients treated with sirolimus.