A 60-year-old woman with diabetes mellitus (DM) for the past 10 years noticed reddish-colored lesions on both anterior shins that turned brown over the past year (Figure 230-1). She reported no pain with the hyperpigmented areas but has neuropathic foot pain. The patient is diagnosed with diabetic dermopathy and begins working with her physician on achieving better control of her diabetes.
Lesions of diabetic dermopathy (also called pigmented pretibial papules) on both lower extremities of a 60-year-old woman with diabetes. The skin appears atrophic, and the lesions are flat and hyperpigmented. (Reproduced with permission from Richard P. Usatine, MD.)
Diabetic dermopathy is a constellation of well-demarcated, hyperpigmented, atrophic depressions, macules, or papules located on the anterior surface of the lower legs that is usually found in patients with DM. It is the most common cutaneous marker of DM.
Diabetic dermopathy is found in 12.5% to 40% of patients and most often in the elderly. It is less common in women.1
In a case series of 100 consecutive inpatients or outpatients in India with DM and skin lesions, diabetic dermopathy was found in 36%.2 The incidence was much lower in a second case series of 500 patients attending a diabetes clinic in India, with only 0.2% diagnosed with diabetic dermopathy; the authors concluded that because most patients were well controlled (fasting blood sugar <130 mg/mL in 60%), cutaneous signs of chronic hyperglycemia were decreased.3 It is also possible that dermopathy is more difficult to see in dark-skinned individuals.
Sometimes seen in persons without DM, especially patients with circulatory compromise.
ETIOLOGY AND PATHOPHYSIOLOGY
The cause of diabetic dermopathy is unknown.
Diabetic dermopathy may be related to mechanical or thermal trauma, especially in patients with neuropathy.
Lesions have been classified as vascular because histology sections demonstrate red blood cell extravasation and capillary basement membrane thickening. In one study, patients with type 1 DM and diabetic dermopathy had marked reduction in skin blood flow at normal-appearing skin areas on the pretibial surface of the legs compared with type 1 control and nondiabetic control patients.4
Dermal changes include fibroblastic proliferation, thickening of collagen bundles and fragmentation or separation of the collagen fibers and edema.5
There is an association between diabetic dermopathy and the presence of retinopathy, nephropathy, and neuropathy.6,7 In a Turkish study, women with diabetic dermopathy appeared to have a more severe sensorial neuropathy (e.g., loss of deep tendon reflexes, superficial sensory loss, and the loss of vibration sense) than did patients without these skin lesions; a high prevalence of carpel tunnel syndrome (63.8%) was also found in these patients.8