Actinic Purpura

7/11/2009 · Kategori: Dermatology

Actinic Purpura

Author: Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Coauthor(s): Vinay Arya, MD, Staff Physician, Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medicine; George Kihiczak, MD, Clinical Associate Professor, Department of Dermatology, New Jersey Medical School and University Hospital

Introduction

Background

Actinic purpura is a benign clinical entity resulting from sun-induced damage to the connective tissue of the dermis. Actinic purpura is characterized by ecchymoses on the extensor surfaces of the forearms and the dorsa of the hands that usually last 1-3 weeks.

Bateman¹ first described the condition in 1818 when he noted dark purple blotches and determined that they were due to the extravasation of blood into the dermal tissue. Hence, it is sometimes called Bateman purpura.

It is common in elderly individuals and usually occurs after unrecognized minor trauma to the respective areas.

Clinical aspects of dermatoporosis include morphological markers of fragility, such as senile purpura, stellate pseudoscars, and skin atrophy.² The concept of the syndrome term dermatoporosis has been used to compare it to osteoporosis, implying both should be prevented and treated to avoid complications.

Pathophysiology

The purple macules and patches of this condition occur because red blood cells leak into the dermal tissue. This extravasation is secondary to the fragility of the blood vessel walls caused by ultraviolet radiation–induced dermal tissue atrophy. This atrophy renders the skin and microvasculature more susceptible to the effects of minor trauma and shearing forces. The insult to the skin is typically so minor that isolating it as a cause of the ecchymoses can be difficult.

Notably, no inflammatory component is found in the dermal tissue. The absence of a phagocytic response to the extravascular blood has been postulated to be responsible for delaying resorption for as long as 3 weeks.

Actinic purpura may be, along with osteoporosis, a sign of collagen loss in skin and bone.³ This causal loss of skin collagen has been confirmed when collagen was expressed absolutely, instead of as a percentage or ratio. That is, women have less collagen than men and it decreases by 1% a year in exposed and unexposed skin. These changes in skin collagen may correspond to changes in bone density. The hypothesis is that the changes in skin collagen also occur in bone collagen, leading to the associated changes in bone density.

Frequency

United States

Actinic purpura is an extremely common finding in elderly individuals, occurring in approximately 11.9% of those older than 50 years. Its prevalence markedly increases with years of exposure to the sun.

International

Data are not available.

Mortality/Morbidity

The ecchymoses may be cosmetically distressing and may leave dyspigmentation or scarring, but the lesions are not associated with any serious complications.

Race

The effects of chronic sun exposure with the resultant ultraviolet radiation–induced skin changes occur more often and are more pronounced in fair-skinned individuals than in others.

Sex

Both sexes are equally affected.

Age

Actinic purpura occurs almost exclusively in the elderly population, though it may sporadically occur in younger people. The incidence varies with respect to age. Approximately 2% of those aged 60-70 years and as many as 25% of those aged 90-100 years can have the purpuric lesions.

Clinical

History

• Patients may report the appearance of purple blotches or bruises on their forearms, hands, face, or neck.
• The macules are not associated with pain or pruritus.
• Constitutional symptoms (eg, fever, malaise, weight loss) are absent.
• The patient may report a history of the lesions resolving and then subsequently reappearing. Residual brown pigmentation may appear after the purpuric macules resolve.
• Individual lesions usually last 1-3 weeks, and they do not undergo the color changes that occur with other types of purpuric lesions.
• Patients are typically unaware of any external trauma that may have been responsible for the ecchymoses.
• Individuals may report a history of chronic sun exposure to skin sites where lesions are present.
• Individuals with actinic purpura are often taking blood-thinning medications such as aspirin or warfarin, which can aggravate the condition.

Physical

• Purpuric patches and macules larger than 3 mm in diameter are usually present on the extensor surfaces of the forearms and on the dorsa of the hands; the lesions do not extend onto the fingers.
  • Ecchymoses may also be found on the neck and face.
  • Macules and patches are dark purple and irregularly shaped.
  • A sharp margin is seen between the borders of the lesions and the surrounding skin.
• Some macules are more deeply colored than others because the duration of the lesions varies. The color changes that are typically associated with purpura or ecchymoses due to other causes do not occur, although residual brown pigmentation may persist.
• Lesions of actinic purpura occur in areas of atrophic and inelastic photodamaged skin.
  • Other signs of dermatoheliosis often present include leathered wrinkling, stellate pseudoscars, and a sallow yellow hue to the skin.
  • Lentigines and scars may be present.
  • The skin may appear darker secondary to hyperpigmentation due to hemosiderosis.

Causes

• Chronic sun exposure leads to skin changes that predispose patients to actinic purpura.
• Because of the ultraviolet-induced atrophy, the connective tissue of the dermis is no longer able to adequately support the microvasculature.
• As a result, even minor trauma can tear the blood vessels, leading to the extravasation of blood.