HISTORY
Chief complaint: presenting for diagnosis and therapeutic options.
History of present illness: A 44-year-old male with a personal and family history of diabetes presents with darkened and thickened skin on his axilla, groin, and back, which he says has developed over the year. Prior treatment for skin condition: none. His primary symptom: occasional pruritus. Prior biopsy: none.
IMAGE QUALITY ASSESSMENT
Fully satisfactory.
TELEDERMATOLOGY IMAGING READER REPORT
There are two images provided with this consult. The first image shows the posterior neck, upper back, and bilateral posterior axilla and inferior arms of an obese male with hyperpigmented, dark-brown, velvety plaques (see Figure 1). The second image shows similar morphological plaques located over the spine and transverses across the lower back (see Figure 2).
INTERPRETATION OF IMAGES
Lesion A
Findings
The morphology of the lesions, distribution, and history are characteristic for acanthosis nigricans (AN).
RECOMMENDATIONS
Skin Care Recommendations
Use topical tretinoin 0.05% cream nightly or ammonium lactate cream 12% daily or a combination of the two if tolerated.
Other treatment recommendations: As this is often a sign of an underlying systemic disease, the correction of underlying condition is needed. Exercise and diet to aid in weight loss. Given the symptoms, supplementation with omega 3 (dietary fish oils) is also recommended, if there are no contraindications.
RECOMMENDED FOLLOW-UP
Type of Visit
Follow up with primary care physician to evaluate for malignancy or syndromic AN associated with uncontrolled diabetes mellitus or an autoimmune disease such as Hashimoto thyroiditis.
CLINICAL PEARL
AN usually presents as hyperpigmented, "velvety" plaques in intertriginous areas, with the neck, armpit, and groin being the most common sites affected. AN is seen equally in men and women but does have a predilection for darker skin types and a higher prevalence with increasing age (Kutlubay, Engin, Bairamov, & Tuzun, 2015). Affected areas are usually asymptomatic. The mainstay of treatment is to identify and treat the underlying cause.
Most cases of AN are associated with insulin resistance, with obesity being the most common cause. Other insulin-related causes include Type 2 diabetes mellitus and polycystic ovarian syndrome, which would warrant work-up in an overweight patient presenting with signs of AN. In general, lesions will resolve or lighten with treatment of the underlying disease. For example, correction of hyperinsulinemia notably reduces the hyperkeratotic lesions, as does cessation of the inciting medication in the drug-induced form. Drug-induced AN has been reportedly associated with oral contraceptives, nicotinic acid, and corticosteroids among other medications (Kutlubay et al., 2015). An important cause of AN to remember is malignancy. Malignant AN is most commonly associated with gastric adenocarcinoma, but many other cancers have been reportedly associated (Kutlubay et al., 2015). Signs that AN may be associated with an underlying malignancy include sudden onset of AN, associated pruritus, and mucosal involvement (Higgins, Freemark, & Prose, 2008).
All systemic causes of AN should be ruled out and the underlying systemic disease process should be treated. If lesions do not resolve with treatment of the underlying disease or if no cause is found, the patient should be reassured of the benign nature of this condition. Reported treatments in the literature include retinoids (topical or oral), topical calcipotriol, and other combination options, although their uses are considered off-label and may not be covered by insurance.1
REFERENCES