<prompt> A 30 years old male presented with silvery scales on elbow and knee, which bleed on removal. The probable diagnosis is:PityriasisSeborrheic dermatitisPsoriasisSecondary syphilis  <response>: Ans. C. PsoriasisPsoriasis Silvery white scales due to air trapped between scales Removal of scales lead to appearance of punctuation pinpoint bleeding points Auspitz sign Grattage test: Scratching with a glass slide accentuates scale formation in a psoriatic plaque. Scales are absent in flexural psoriasis and on glans in un-circumscribed patients Scaling is profuse in elephantine and rapid psoriasis.Seborrheic dermatitis Greasy scalesPityriasis rosea Collarette scales which are attached to peripheral edge and free towards center 