The papulosquamous diseases have certain common morphologic appearances which may at times lead to confusion in diagnosis. They do not have any common etiologic factor. The most common diseases in this category are psoriasis, seborrheic dermatitis, lichen planus, pityriasis rosea, and secondary syphilis. Exfoliative erythroderma is included here since it rarely may be a complication of a pre-existing papulosquamous disease such as psoriasis, seborrheic dermatitis, and lichen planus.
丘疹鳞屑性疾病有某些共同的形态学表现，有时可能导致诊断上的混淆。它们没有任何共同的病因。这类疾病中最常见的是银屑病、脂溢性皮炎、扁平苔藓、玫瑰糠疹和二期梅毒。剥脱性红皮病也包括在此，因为它很少可能是先前存在的丘疹鳞屑性疾病（如银屑病、脂溢性皮炎和扁平苔藓）的并发症。
