What is Pityriasis rosea?

Pityriasis Rosea refers to rash thought to be caused by the Herpes virus type 7

Natural history:

The earliest manifestation of Pityriasis Rosea is a herald patch - an oval patch with scaling on the outside and clearing on the inside.  The herald patch is often mistaken for a fungal infection (ringworm).

An interval of a few days follows the herald patch, with no additional rash.

Following this interval, a generalised eruption develops, with crops appearing every two to three days for about 10 days.  The eruption is made up small ovals which align themselves in the pattern of a Christmas tree.  This pattern is most pronounced on the back but is often evident on the chest and abdomen as well.  The upper third of the limbs are frequently involved.  The rash is unusual on the face and hands.

The rash of Pityriasis Rosea lasts about 6 - 8 weeks and usually disappears without trace.  In pigmented individuals, some degree of darkening may be seen where the rash was present.  This fades over time.

What other conditions can look like Pityriasis Rosea?

Ringworm

Eczema

Psoriasis

Allergic reaction to medicines

Treatment:

Topical steroids

For severe cases, systemic steroids may be administered

UV light helps in the resolution of the rash.

 

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© Dr N Raboobee 2010