5. Psoriasis Diseases
Psoriasis is a long-lasting skin disease that results in patches
(called plaques) of thick, red skin covered with silvery scales.
Doctors usually diagnose psoriasis after a careful
examination of the skin. However, diagnosis may be
difficult because psoriasis symptoms can be similar to
those of other skin diseases. A pathologist may assist with
diagnosis by conducting a biopsy: that is, examining a
small skin sample under a microscope.
There are several forms of psoriasis. The most common
form is plaque psoriasis (its scientific name is psoriasis
vulgaris). In plaque psoriasis, lesions have a reddened base
covered by silvery scales. Other forms of psoriasis include
