Muir–Torre syndrome

Muir–Torre syndrome
Sebaceous adenoma - low mag.jpg
Micrograph of a sebaceous adenoma, commonly associated with Muir–Torre syndrome. H&E stain.
Synonyms	MTS
Specialty	Oncology, Dermatology, Genetics
Symptoms	Sebaceous tumors, internal malignancies
Complications	Colorectal cancer, genitourinary cancers
Usual onset	Usually adulthood
Duration	Lifelong
Causes	Genetic mutations in MLH1, MSH2, MSH6 genes
Risk factors	Family history of Lynch syndrome
Diagnosis	Clinical presentation, genetic testing, immunohistochemistry
Differential diagnosis	Sporadic sebaceous tumors, other hereditary cancer syndromes
Prevention	Regular screening, genetic counseling
Treatment	Surgical excision, regular cancer surveillance
Prognosis	Good with early detection and management
Frequency	Rare
Deaths	Usually related to complications from malignancies

Muir–Torre syndrome (MTS) is a rare, hereditary autosomal dominant cancer syndrome, considered a subtype of Lynch syndrome (Hereditary Non-Polyposis Colorectal Cancer, HNPCC). Individuals with this syndrome have an increased susceptibility to cancers of the colon, genitourinary tract, and distinct skin lesions, including keratoacanthomas and sebaceous tumors such as sebaceous adenoma, sebaceous epithelioma, and sebaceous carcinoma.

Signs and Symptoms

Characteristic features include:

• Presence of at least one sebaceous gland tumor (adenoma, epithelioma, or carcinoma)
• Occurrence of at least one internal malignancy, commonly colorectal or genitourinary cancers

Genetics

Muir–Torre syndrome is caused primarily by mutations in the MLH1, MSH2, and more recently identified MSH6 genes. These genes are critical for the DNA mismatch repair pathway. Mutations result in defective DNA repair mechanisms, increasing the risk of developing cancers.

Diagnosis

Diagnosis typically involves:

• Clinical evaluation of sebaceous skin tumors and internal malignancies
• Genetic testing for mutations in DNA mismatch repair genes
• Immunohistochemical analysis for mismatch repair proteins
• Application of the Amsterdam criteria, widely used to diagnose Lynch syndrome and Muir–Torre syndrome, which include:
  • At least three relatives affected by Lynch-associated cancers (colorectal, endometrial, small bowel, ureter, renal pelvis)
  • Cancer affecting at least two successive generations
  • At least one individual diagnosed before age 50
  • Exclusion of familial adenomatous polyposis

The Mayo Muir–Torre risk score was developed to enhance diagnostic accuracy, distinguishing true cases from sporadic sebaceous tumors.

Management

Treatment strategies involve:

• Surgical removal of skin lesions
• Regular screening and surveillance for internal malignancies (colonoscopies, genitourinary screenings)
• Genetic counseling for patients and their families

Prognosis

With appropriate management and regular surveillance, the prognosis for individuals with Muir–Torre syndrome can be favorable. Early detection and treatment of malignancies significantly improve outcomes.

Prevention

Preventive measures focus on:

• Early genetic screening and counseling for at-risk families
• Frequent surveillance for early detection of malignancies

Muir–Torre syndrome remains a rare condition, requiring multidisciplinary care involving dermatologists, geneticists, oncologists, and surgeons.

Eponym

It is named for EG Muir and D Torre. A British physician, Muir noted a patient with many keratoacanthomas who went on to develop several internal malignancies at a young age. Torre presented his findings at a meeting of the New York Dermatologic Society.

See also

• List of cutaneous conditions
• List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer