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Wednesday, June 11, 2008

skin lesions continued[special skin lesions]

TELANGIECTASIA [tel-terminal ,angi-blood vessel.ectasia-dilation]

Telangiectasia are the permanent dilatation of superficial blood vessels in the skin and may occur as isolated phenomena or as part of a generalized disorder, such as ataxia telangiectasia.

Telangiectasia

  1. they can develop anywhere on the body but commonly on the face around the nose, cheeks, and chin.
  2. Chronic treatment with topical corticosteroids may lead to telangiectasia
  3. Telangiectasias may occur in a number of diseases:
    CREST syndrome (a variant of scleroderma)
    hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome)
    Ataxia telangiectasia
    Carcinoid syndrome
    Acne rosacea


petechiae:

minute 1 to 2 mm hemorrhages into skin.

typically associated with-

  • locally increased intravascular pressure
  • low platelet count
  • defective platelet function clotting factor deficits.
  • note-Petechiae on the face and conjunctiva (eyes) are a sign of a death by asphyxiation. They are thought to result from an increase of pressure in the veins of the head and hypoxic damage to endothelial of blood vessels

petechiae

purpura:

slightly larger (more than or equal to 3 mm to 1 cm)hemorrhages .

associated with-

  • the same disorders that cause petechiae
  • secondary to trauma
  • vascular inflammation(vasculitis)as in the case of Henoch-Schönlein purpura.
  • increased vascular fragility(as in amyloidosis)

purpura

ecchymosis:

larger(more than 1 cm) subcutaneous hematomas.

characteristically seen after trauma but may be exacerbated by any of the aforementioned conditions.

ecchymosis

Burrow:

A burrow is a tunnel or linear train in the epidermal layer of the
skin caused by a parasite.

The contagious, parasitic skin disease scabies is a good
example of a parasite burrowing. The skin damage is caused by the female Sarcoptes scabiei who excavates a burrow in the stratum corneum layer of the epidermis, lays her eggs and dies. The larvae emerge, moult, and the females are fertilized. The most common sites in which the parasite enters the skin are between the fingers, the hands,and the wrists.

The infection can persist for months or years if a person is not treated, a situation which gave rise to the expression "the seven-year itch."

other examples are due to cutaneous larva migrans.{skin disease in humans, caused by the larvae of various nematode parasites, the most common of which is Ancylostoma braziliense.}

burrows

Comedo (blackhead). A comedo or blackhead develops when
sebaceous glands become enlarged because of accumulated serum. Blackheads more commonly happen during adolescence and are usually found over the face, chest, and back. The color of blackheads is caused by melanin and oxidized oil, not dirt. A blackhead is of cosmetic rather than medical importance.

acne


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