Purpuric lesions are caused by an extravasation of red blood cells into the skin or mucous membranes. The lesions can be distinguished from erythema and telangiectasia by the fact that purpuric lesions do not blanch under pressure applied by the finger or by diascopy.
Petechiae are small, superficial purpuric lesions. Ecchymoses, or bruises, are more extensive, round or irregularly shaped purpuric lesions. Hematomas are large, deep, fluctuant, tumor-like hemorrhages into the skin.
The purpuras can be divided into the thrombocytopenic forms and the nonthrombocytopenic forms.
Thrombocytopenic purpura may be idiopathic or secondary to various chronic diseases or to a drug sensitivity. The platelet count is below normal, the bleeding time is prolonged, and the clotting time is normal, but the clot does not retract normally. This form of purpura is rare.
Nonthrombocytopenic purpura is more commonly seen. Henoch-Schunlein purpura is a form of nonthrombocytopenic purpura most commonly seen in children that is characterized by recurrent attacks of purpura accompanied by arthritis, hematuria, IgA glomerulonephritis, and gastrointestinal disorders.
The ecchymoses, or senile purpura, seen in elderly patients after minor injury are very common. Ecchymoses are also seen in patients who have been on long-term systemic corticosteroid therapy and also occur after prolonged use of the high-potency corticosteroids locally and from corticosteroid nasal inhalers.
Another common purpuric eruption is that known as stasis purpura. These lesions are associated with vascular insufficiency of the legs and occur as the early sign of this change, or they are seen around areas of stasis dermatitis or stasis ulcers.
Frequently seen is a petechial drug eruption due to the chlorothiazide diuretics.
A less common group of cases are those seen in middle-aged adults, classified under the name pigmented purpuric eruptions. Some cases of pigmented purpuric eruptions itch severely. The cause is unknown; most cases have a positive tourniquet test, but other bleeding tests are normal. Clinically, these patients have grouped petechial lesions that begin on the legs and extend up to the thighs, and occasionally up to the waist and onto the arms.
Some clinicians are able to separate these pigmented purpuric eruptions into purpura annularis telangiectodes (Majocchi's disease), progressive pigmentary dermatosis (Schamberg's disease), and pigmented purpuric lichenoid dermatitis (Gougerot and Blum disease). Majocchi's disease commonly begins on the legs but slowly spreads, to become generalized. Telangiectatic capillaries become confluent and produce annular or serpiginous lesions. The capillaries break down, causing purpuric lesions. Schamberg's disease is a slowly progressive pigmentary condition of the lower part of the legs that fades after a period of months. The Gougerot-Blum form is accompanied by severe itching and eczematous changes; otherwise it resembles Schamberg's disease.
For these pigmented purpuric eruptions, therapy may not be necessary. Occlusive dressing therapy with a corticosteroid cream can be beneficial.
For resistant cases, prednisone, 10 mg, 1 to 2 tablets in the morning for 3 to 6 weeks, is indicated.
Telangiectases are abnormal dilated small blood vessels. Telangiectases are divided into primary forms, in which the causes are unknown, and secondary forms, which are related to some known disturbance.
The primary telangiectases include the simple and compound hemangiomas of infants, essential telangiectasias, and spider hemangiomas (see Chap...32). Diseases with numerous telangiectasias include cirrhosis of the liver, Osler-Weber-Rendu disease, lupus erythematosus, scleroderma, dermatomyositis and rosacea. Secondary telangiectasia is very commonly seen on the fair-skinned person as a result of aging and chronic sun exposure. X-ray therapy and burns can also cause dilated vessels.
Treatment for the secondary telangiectasias can be accomplished quite adequately with very light electrosurgery to the vessels, which is usually tolerated without anesthesia or for many extensive lesions use of laser therapy. Injectable sclerosing agents are available for therapy on the lower legs.
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