Cutaneous clues: Specific dermatologic conditions can aid in diagnosis of metabolic syndrome

Key Points

Long Beach, Calif. - It is well known that the skin often reflects internal pathology. Following this notion, there are several cutaneous manifestations that a psoriasis patient can present with (other than the classic psoriasis symptoms) that can clue a dermatologist in on components of metabolic syndrome.

Existing evidence

"Fat is not simply an inner mass of adipocytes but is metabolically active, secreting cytokines known as adipocytokines such as TNF-alpha, IL-6, adiponectin and others. When people gain weight and reach a certain critical mass, the action of lipases in the fat cells cause the release of free fatty acids, which in turn go to the liver and change the metabolism of fat secretion, resulting in low HDLs and high LDLs, also known as dyslipidemia," says Frank J. Dann, M.D., professor of the department of dermatology, Long Beach Veterans Affairs Medical Center, Long Beach, Calif.

Skin signals

Dyslipidemia can present as eruptive xanthomas, which often appear on the buttocks and extensor surfaces. The condition is called xanthelasma when they occur on the lower eyelids. According to Dr. Dann, eruptive xanthomas can be a cutaneous symptom of dyslipidemia and familial hypertriglyceridemia, which in turn is associated with a higher risk of developing diabetes as well as cardiovascular disease.

Obesity is common in psoriasis, and even those patients with minimal psoriasis who are also obese have a higher risk for coronary artery disease. Obesity is associated with elevated levels of C-reactive protein secreted by fat cells and stimulated by IL-6. Obese people have high levels of C-reactive protein, which is an acute-phase reactant that is elevated in patients who have coronary disease. So, obese patients who have even minimal psoriasis could be at risk for coronary artery disease.

Skin tags are commonly seen in the obese, and they are another cutaneous sign associated with metabolic syndrome. Adipocytes secrete TNF-alpha, which is known to cause insulin resistance and elevated insulin levels in the blood. According to Dr. Dann, elevated levels of circulating insulin are associated with the presence of acrochordons.

"An overweight patient presenting with skin tags may have a higher risk of having metabolic syndrome, because skin tags could be a sign of insulin resistance or frank diabetes, which is again part of the metabolic syndrome. These patients should have their blood pressure and glycosylated hemoglobin checked to be sure that they are not diabetics. Skin tags could be a marker for two of the components of the metabolic syndrome, namely obesity and diabetes," Dr. Dann says.

Acanthosis nigricans is associated with several different diseases, including malignancies and endocrinopathies. However, one of the most common associations with this skin manifestation is obesity. Though the mechanism is not clear, it is thought that the increased insulin levels stimulate insulin-like growth factors in the skin, which in turn stimulate the growth of the keratinocytes and dermal fibroblasts.

"Like skin tags, acanthosis nigricans can be a marker for dyslipidemia, and both of these cutaneous manifestations are commonly seen in the setting of obesity," Dr. Dann says.

Another less common skin manifestation that can be associated with components of metabolic syndrome is calciphylaxis. This often occurs in the setting of renal disease, where there is a calcification of the small arteries of the dermis and subcutaneous fat, commonly over the breast, abdomen and thighs. It is primarily seen in diabetics.

Calciphylaxis is more common in diabetic women, and is viewed as a serious disease characterized by thromboses leading to ulcerations, which serve as portals of infection, often resulting in poor outcomes. According to Dr. Dann, anyone with calciphylaxis should be checked for diabetes, especially if they are overweight.

"It is important to remember that the cutaneous manifestations that are most commonly seen in the skin are the ones that lead back to obesity and insulin resistance. For instance, hypertension does not have any skin markers and can be silent, very different from obesity, insulin resistance, diabetes and dyslipidemia," Dr. Dann explains.

Scleredema is a cutaneous manifestation seen in diabetics characterized by a thickening of the skin over the shoulders and upper back. It is also known as diabetic thick skin syndrome. Diabetic hand syndrome is yet another typical skin manifestation seen in diabetics, in which there is a morphologic change over the knuckles characterized by a peculiar hyperpigmented pebbling of the skin. This can be a marker for occult diabetes.