The LEAST common site of involvement in psoriasis is (AIPG 2011)
Sites affected in psoriasis
1). Extensor aspects of the trunk and limbs
2). Knee, elbow and scalp are especially frequently affected, although the mocosa seam to be spared
3). Nails - thimble, pitting onycholysis, subungual debris
4). Face is not usually severely affected.
5). Psoriatic arthritis - 5-10% patients - (RA-factor is negative)
6). Inverse psoriasis, flexor surface is more involved, itching is present and usually no scales.
7). CNS involvement is not seen.