Peutz–Jeghers syndrome (PJS) is a rare hereditary disorder of polyposis. It is characterized by gastrointestinal polyps, mucocutaneous pigmentation, recurrent abdominal pain from intussusceptions, and an increased risk of intestinal and other malignancies. The pigmented macules of PJS are typically found around the mouth, eyes, nostrils, and anus; they may also be seen on the hands and feet. These brown to black macules are often round or oval, 1 to 5 mm in diameter, and irregular in shape. They may occasionally manifest with a blue-gray hue. Clinically and histologically, these are simple lentigines. Most patients with this autosomal dominant disorder have a germline mutation of the STK11/LKB1 (serine/threonine kinase 11) tumor suppressor gene, located at chromosome 19p13.3. A more recently identified second PJS disease locus exists at 19q13.4. The exact mechanism of cancer and hamartoma development remains unclear. Genetic testing may be useful in equivocal cases, as well as in counseling of at-risk families; however, it is not 100% sensitive.
Elsevier, Treatment of Skin Disease (Fifth Edition) Comprehensive Therapeutic Strategies 2018, Pages 621-623