Diabetic dermopathy is the most common dermatosis associated with diabetes mellitus. It is found in up to 50% of diabetics, but being asymptomatic, it is commonly overlooked. Men are frequently affected more than women. It is seen more frequently in older patients, and in those who have had diabetes mellitus for a longer period of time.
It begins as flat-topped, dull-red papules that are oval, discrete or grouped, and situated mainly on the pretibial areas. Involvement of the forearms and thighs has been recorded. As the lesions evolve slowly, they develop a thin scale leaving an atrophic brownish scar-like macule, sometimes called diabetic shin spots or brown pseudoscars. The colour of the scar-like macules is due to haemosiderin in histiocytes near the vessels. It should be noted that such lesions are not specific to diabetes mellitus. However, if four or more are present the specificity is high for diabetes.
It has been suggested that the lesions represent an exaggerated response to trauma in skin overlying bony prominences and that there may be an underlying diabetic microangiopathy and neuropathy. When questioned patients are often unable to detail preceding trauma. Blood flow levels are considerably higher at the dermopathy sites than at contiguous uninvolved skin sites, refuting the theory that they are ischaemic in origin.
Although not confirmed in all studies, some suggest that there is a significant correlation between the presence of diabetic dermopathy and other complications of diabetes, such as retinopathy, nephropathy and neuropathy. This remains controversial and it is generally regarded that diabetic dermopathy is not directly associated with an increase in morbidity.
In the early lesions, there are oedema of the papillary dermis and a mild perivascular lymphocytic infiltrate with some extravasation of red blood corpuscles. There may be mild epidermal spongiosis and focal parakeratosis. Hyaline microangiopathy can be seen leading to PAS-positive thickening of the vessel wall. In atrophic lesions there are neovascularization of the papillary dermis, a sparse perivascular infiltrate of lymphocytes, and haemosiderin in histiocytes. Haemosiderin can also be present in the epidermis, between basal cells and along the basement membrane. Perivascular plasma cells can be seen whenever there is haemosiderin deposition in the skin.
No treatment is necessary for diabetic dermopathy.
This page was last updated in November 2012.