B. Skin manifestation that correlate with chronic degenerative changes
- Diabetic dermopathy:1,2,3,4,7 [Shin spots, Pigmented Pretibial patches.] Dermopathy is most common cutaneous manifestation of microangiopathy and possibly neuropathy of diabetics. The skin lesions are multiple, bilateral, atrophic circumscribed, symptomatic, pigmented areas affecting predominantly the pretibial areas of legs, forearms, thighs and bony prominences. They are seen in about 50% of patients, more frequently in men. These are not specific for diabetics and do not correlate with duration and severity of disease.
- Diabetic bullae:1,2,3,4,8 The bullae which develop spontaneously intraepidermally or subepidermally, are painless, clear, non-inflammatory, vary in size from a few millimeters to 3-5 cm, present mostly on hands and feet and heal without scarring in 2-5 weeks time. The etiology is unknown but cation imbalance (calcium and magnesium) could be a possible casual factor.
- Scleroderma adultorum of Buschke:1,3,9 It is a firm, non pitting oedema and induration of skin and develop following bacterial infection, usually due to streptococci, occurring on the upper back, neck and shoulder in about 2-5% of diabetics. The hands and feet are spared. Male diabetics are more affected. It undergoes spontaneous resolution over several months may have systemic involvement primarily in obese patient with long standing diabetes and vascular insufficiency. Odema and induration are due to deposition of acid mucopolysaccharidase in the dermis.
- Diabetic rubeosis:2,3,4 It is a peculiar rosy reddening of face and sometimes of hand and feet, found in many patients with long standing diabetes. It has been attributed to reduced vascular tone.
- Erysipelas like erythema:2,3,4,5 Painless, well demarcated, oedematous, red area occur on the legs and feet of elderly long standing diabetic patient. Underlying destructive bone disease may be present in some cases.
- Diabetic neuropathy:1,2,3,4 A distal, symmetrical mixed polyneuropathy involving both the motor and sensory nerves develops in elderly patient with long standing diabetes. Motor neuropathy in feet results in dorsally subluxated digit, distal displacement of planter fat pads, depressed metatarsal heads, hammer toes and pes cavus. A circular punched out, painless perforating ulcer may develop on pressure points of structurally deformed feet (melan perforans). This is attributed to loss of temperature and pain sensation. Autonomic neuropathy results in loss of sweating of lower extremities with compensatory hyperhydrosis of the trunk and face. Thickening, abnormal curvature and hypertrophy of nail plate may occur on chronic pressure to toe nails.
- Peripheral vascular disease:2,3,4 Intermittent claudication with shiny, atrophic and cool skin of distal extremities occur in long standing diabetic patient. This is due to associated atherosclerosis of vessels.
C. Cutaneous manifestations that are associated with diabetes but not specific to it
- Nacrobiosis lipoidica diabeticorum:1,2,3,4,5,10,11 It is frequently associated with diabetes with prevalence of 0.1 to 0.3%. It usually develops in young adult and in early middle age with female to male ratio of 3:1. The lesions are characteristically present on pretibial skin and less often over trunk, arm, face and scalp. The lesions can be single or multiple and unilateral or bilateral. The typical lesions are asymptomatic sharply demarcated oral plaque with yellow central atrophic are and indurated erythmatous border. The overlying superficial telangiectasia and scattered hyperkeratotic plugs often are noted. The underlying pathology is obliterative endateritis with secondary necrobiotic changes in the bundle of collagen.
NLD precedes the onset of diabetes in about 15% of patients by 2 years while in 25% of patients both occur concomitantly. In the rests, NLD appears after developments of diabetes.
Spontaneous resolution occurs in 13-19% of cases after an average of 6 to 12 hears. 90% of persons with NLD are either diabetic, will develop diabetes, or have family history of diabetes. Therapy of NLD is generally unsatisfactory with preference to topical applications or local injection of corticosteroids in some early lesions. Elder et al produced resolution of lesions with antiplatelet agents like aspirin and dipyridamole.
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Acanthosis nigricans:1,2,3,4,12,13 It manifests as brown velvety, hyperkeratotic plaque over axillae, back of neck and other flexural surfaces. Tissue resistance to insulin with hyper-insulinaemia is the pathology.
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Perforating dermatoses:2,3,4,5 These are groups of disorder in which the dermal material perforate through the epidermis out of the surface of skin. This includes perforating collagenosis, kyrle’s disease, perforating folliculitis and elastosis perforans serpinginosa. These are usually associated with diabetics patient with chronic renal failure.
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Granuloma annulare: 1,2,3,4,14 It is rarely seen in diabetics and characterized by an annular configuration of pale, red papules and plaques that occur in a localized or generalised pattern. Cases of DM with disseminated perforating type of GA have been reported, in which there is symmetrical eruptions of hundreds of papules all over the body. Etiology is unknown.
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Generalized Pruritus: 1,2,3,4 It is not a feature of DM and usually present in patients with pruritus valvae and ani. Prutius from any cause should be treated to prevent secondary bacterial infection.
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Acrochordons (Skin tags):2,3,4,15,16 These are bilateral small, soft, hyperpigmented, pedunculated lesions occurring on the eyelids, neck and axillae and often associated with obesity. These are more common in type-2 DM.
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Stiff joints and waxy skin:2,3,4 Waxy, thick tight skin on the back of hands and joints limitation are seen in long standing type-I diabetic patients. This is associated with limited joint mobility affecting mainly the small joints of hand (cheiroarthropathy). Increased collagen crosslinking due to elevated non-glycosylated end products, is the underlying pathology.
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Vitilligo:1,2,3,4,17 A 4.5% to 7.7% frequency has been reported in adult onset diabetes (Type-2). Though associated with both types of diabetes, it is see after the age of 40 years. Also association is more common in patient with multiglandular deficiencies.
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Haemochromatosis:2,3,4 DM is found in 65% patients with haemochromatosis in which there is a defuse bronzed hyper pigmentation due to deposition of melanin and haemosiderin in skin.
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Prophyria cutanea tarda:2,3 About 25% of men between ages 45 to 75 years with PCT have diabetes. This manifests with vesicles, bullae and erosions leaving behind scarring, milia, skin fragility and hypertrichosis over hands, face and other sun exposed areas.
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Periungal telangiectasia:2,3 Associated with 2/3rd of DM patients. There is nail fold erythema with ragged cuticles and finger tips tenderness. Under magnification there is loss of capillary loops with dilation of the remaining.
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Lipodystrophy: 1,2,3,4,5 There is partial or total absence of subcutaneous fat usually affecting the face, neck, trunk and extremities and occur over several months or years. Superficial vein and muscles become prominent. Fat loss can include the palms and soles. Generalized lipodystrophy is associated with severe insulin resistance and is often accompanied by acanthosis nigricans and dyslipidaemia. Localized lipodystrophy is associated with insulin injection therapy.
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