What is the role of imaging studies and procedures in the diagnosis of psoriasis?

Updated: Mar 17, 2021
  • Author: Jacquiline Habashy, DO, MSc; Chief Editor: William D James, MD  more...
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Although most cases of psoriasis are diagnosed clinically, some, particularly the pustular forms, can be difficult to recognize. In these cases, dermatologic biopsy can be used to make diagnosis. Biopsy of the skin lesion may reveal basal cell hyperplasia, proliferation of subepidermal vasculature, absence of normal cell maturation, and keratinization. A large number of activated T cells are present in the epidermis. Biopsy of acral skin may be less useful as chronic eczematous dermatitis may be psoriasiform and psoriasis  of the palms and soles may show spongiosis more often associated with eczema.

Radiographs of affected joints can be helpful in differentiating types of arthritis. Joint x-rays can facilitate the diagnosis of psoriatic arthritis. Bone scans can identify joint involvement early.

Conjunctival impression cytology has demonstrated an increased incidence of squamous metaplasia, neutrophil clumping, and snakelike chromatin.

When the scales are removed, small droplets of blood appear within a few seconds from exposed vessels in the dermal papillae; this is known as the Auspitz sign.

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