<prompt> A 30 years old male presented with silvery scales on elbow and knee, that bleed on removal. The probable diagnosis isPityriasisSeborrhoeic dermatitisPsoriasisSecondary syphilis  <response>: Morphology of papulesplaques in various papulosquamotas disordersPsoriasis - Erythematous papules and plaques on extensors elbow kneeLichen planus - Violaceous papules with Wickhams striae an flexural surfacePityriasis rosea - Annular plaques on TrunkSeborrheic dermatitis - Yellowish, follicular papules on scalp and face Pityriasis rubra pilaris - Erythematous follicular papules on Trunk dorsum of handSecondary syphilis - Dusky erythematous papulesPityriasis lichenoides et varioliformis acuta - Erythematous edematous papules surmounted by vesiclescrustComing to questionClues in this question are :-Characterstic scales silver scaleInvolvement of elbow kneeBleeding on scale removal Auspitz sign 