A recent article in the British Journal of Dermatology outlined many of the skin conditions that occur in obese patients. As podiatric physicians, we are well aware of the effects of obesity on the lower extremity in relation to biomechanics but allow me to focus on some of the skin conditions in these patients.
Obesity is defined as having a body mass index (BMI) greater than 30 kg/m2. If patients are curious what their BMI is, they can go to this site (http://www.nhlbisupport.com/bmi/bmicalc.htm  ) to calculate it. A prevalent problem not only in the United States but worldwide, obesity affects all populations from children to the elderly. Obviously, in our profession, we mostly see obese patients who are about to be diagnosed with diabetes or already have the disease.
The patients who may not have been diagnosed with diabetes may present with acanthosis nigricans, which can be a sign of insulin resistance. Acanthosis nigricans is a hyperpigmented, velvety discoloration that occurs in skin folds. If the patient complains of this on the neck (“My neck is always dirty”), axilla or discoloration in another area, one should screen the patient for diabetes, other endocrine disorders and malignancy.
One of my particular areas of interest, psoriasis, can be related to obesity either due to lack of activity (think of the inflamed plantar foot affected by psoriasis) or the presence of psoriatic arthritis (enthesopathies at the Achilles and plantar fascia attachments). However, one can also view obesity as a sequela of psoriasis and the concomitant metabolic syndrome. The metabolic syndrome that occurs in psoriasis increases that patient’s risk of a cardiovascular event, hypertension and atherosclerosis. Weight loss either through increased activity or bariatric surgery does seem to improve the signs and symptoms of psoriasis.
Some more rare effects of obesity on the skin would include a pretibial myxedema-like reaction on the anterior tibia. Most of us learned that when we see this peau d’orange appearance, we should consider thyroid disease. We certainly should although there have been a few cases of this skin disease occurring in obese patients in the absence of thyroid disease. The authors who described this would like us to consider it as a subtype of pretibial myxedema: chronic obesity lymphedematous mucinosis.
Keratoderma climacterum presents as cracking and fissuring of the plantar heel that may progress distally along the sides of the foot. Our patients who visit us for this condition have pain on ambulation and can often only wear slippers or socks to walk. This has a strong correlation with obesity.
Obviously, moisturizing is a key treatment but oral acitretin (Soriatane, GlaxoSmithKline) can help decrease the skin thickness in severe cases. One should prescribe this medication with careful consideration as it is generally not recommended in women of childbearing age. Women should not conceive for three years after finishing the medication and both men and women should avoid donating blood for three years after finishing the drug.
In addition to the entities mentioned above, we can also see the following in our obese patients: decreased wound healing due to leptin resistance, varicose veins, venous insufficiency, venous stasis dermatitis and venous ulcers. Other conditions include erythrasma caused by Corynebacterium, cellulitis related to leg lymphedema and methicillin resistant Staphylococcus aureus (MRSA) and candidal infections in the skin folds. The recurring soft tissue infections in the leg can lead to elephantiasis nostras verrucosa or to the hypertrophic, indurated, verrucous lesions we see in our chronic lymphedema patients.
1. Shipman AR, Millington GWM. Obesity and the skin. Br J Derm. 2011; 165(4):743-750.