science

Muir–Torre syndrome

Muir–Torre syndrome is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Muir–Torre syndrome rather than just read about it. In short: Muir–Torre syndrome is a rare hereditary, autosomal dominant cancer syndrome that is thought to be a subtype of HNPCC (Lynch syndrome). Individuals are prone to develop cancers of the colon, genitourinary tract, and skin lesions, such as keratoacanthomas and sebaceous tumors.

Key takeaways

Muir–Torre syndrome belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Muir–Torre syndrome to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Muir–Torre syndrome from memory before moving on to harder problems.

Reference excerpt

Muir–Torre syndrome is a rare hereditary, autosomal dominant cancer syndrome that is thought to be a subtype of HNPCC (Lynch syndrome). Individuals are prone to develop cancers of the colon, genitourinary tract, and skin lesions, such as keratoacanthomas and sebaceous tumors. The genes affected are MLH1, MSH2, and more recently, MSH6, and are involved in DNA mismatch repair.

Signs and symptoms Muir–Torre syndrome is characterized by both:

At least a single sebaceous gland tumor (either an adenoma, an epithelioma, or a carcinoma) A minimum of one internal malignancy The Amsterdam criteria are frequently used to diagnose Lynch syndrome and Muir–Torre syndrome. They include the following:

3 or more relatives with an HNPCC-associated cancer (i.e., colorectal, cancer of the endometrium, small bowel, ureter, or renal pelvis) 2 or more successive generations affected by cancer 1 or more persons with cancer is a first-degree relative of the other 2, at least 1 case of colorectal cancer younger than age 50 years, a diagnosis of familial adenomatous polyposis has been excluded, and tumors are verified by histologic examination Muir–Torre syndrome is a genetic condition. Mutations in MLH1 and MSH2 are linked with the disease. These genes code for DNA mismatch repair genes, and mutations increase the risk of developing cancerous qualities. Many patients who have sebaceous neoplasms with mutations in MSH2 and MLH1 do not, in fact, have Muir–Torre syndrome. The Mayo Muir–Torre syndrome risk scoring system was devised to improve the positive predictive value of immunohistochemistry and reduce the false positive rate. The Mayo Muir–Torre risk scoring system assigns points based on several characteristics. A score of 2 or greater has a high positive predictive value for Muir–Torre syndrome. A score of 1 or lower is less likely to be Muir–Torre syndrome. Age of onset of first sebaceous neoplasm: <60 years = 1 point, otherwise 0 points Total number of sebaceous neoplasms: 1 = 0 points, >2 = 2 points. Personal history of Lynch related cancers: No = 0 points, Yes = 1 point Family history of Lynch-related cancer: No = 0 points, Yes = 1 point The most common internal malignancies associated with Muir–Torre syndrome are: Colorectal (56%), Urogenital (22%), Small Intestine (4%), and Breast (4%). A variety of other internal malignancies have been reported.

Cause

Genetic overlap with Turcot syndrome A couple of studies have been conducted on patients with both Muir–Torre syndrome and Turcot syndrome. It is thought that the two may have some genetic overlap. Both have been associated with defects in MLH1 and MSH2 genes. In one study, a patient with defective MSH2 and MSH6 mismatch repair genes exhibited both syndromes. This is the first case where a patient with genotypic changes consistent with HNPCC has been properly diagnosed with an overlap of both syndromes. Along with neoplasms of the sebaceous gland, this patient developed cerebral neoplasms, characteristic of Turcot syndrome.

Diagnosis Immunohistochemistry is now being used more often to diagnose patients likely to have Muir–Torre syndrome. Sebaceous neoplasms are only infrequently encountered, and immunohistochemistry is reliable and readily available, so researchers have recommended its use. Routine immunohistochemical detection of DNA mismatch repair proteins helps identify hereditary DNA mismatch repair deficiency.

Treatment Treatment of Muir–Torre syndrome normally consists of oral isotretinoin. The drug has been found to prevent tumor development. Patients with Muir–Torre syndrome should follow the same stringent screening for colorectal carcinoma and other malignancies as patients with Lynch syndrome. This includes frequent and early colonoscopies, mammograms, dermatologic evaluation, and imaging of the abdomen and pelvis.

Epidemiology Muir–Torre was observed to occur in 14 of 50 families (28%) and in 14 of 152 individuals (9.2%) with Lynch syndrome, also known as HNPCC. The two major MMR proteins involved are hMLH1 and hMSH2. Approximately 70% of tumors associated with the MTS have microsatellite instability. While germline disruption of hMLH1 and hMSH2 is evenly distributed in HNPCC, disruption of hMSH2 is seen in greater than 90% of MTS patients. Gastrointestinal and genitourinary cancers are the most common internal malignancies. Colorectal cancer is the most common visceral neoplasm in Muir–Torre syndrome patients.

Eponym The syndrome is named for Edward Grainger Muir and Douglas P. Torre. A British physician and surgeon, Muir noted a patient with many keratoacanthomas who went on to develop several internal malignancies at a young age in the 1960s. Torre, a New York dermatologist, presented his findings at a meeting of the New York Dermatologic Society. It was not until the 1980s that Creighton professor Henry T. Lynch noted a clustering of Muir–Torre syndrome patients in families with Lynch syndrome.

See also List of cutaneous conditions List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with Muir–Torre syndrome

Start with the simplest possible case. Write down what Muir–Torre syndrome claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Muir–Torre syndrome before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Muir–Torre syndrome ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Muir–Torre syndrome

In research: Muir–Torre syndrome appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Muir–Torre syndrome in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Muir–Torre syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics DNA replication and repair-deficiency disorders, Epidermal nevi, neoplasms, and cysts, Syndromes, so understanding it makes those chapters shorter.
In everyday life: Look for Muir–Torre syndrome outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Muir–Torre syndrome” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Muir–Torre syndrome in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Muir–Torre syndrome means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Muir–Torre syndrome out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Muir–Torre syndrome in simple terms?

Why does Muir–Torre syndrome matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Muir–Torre syndrome?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Muir–Torre syndrome.