Introduction

[|This is a wonderful grouping of 39 clinical photographs, mirroring my earlier comments about the tremendous variation in phenotypic expression of this disease we call psoriasis. My great friend, the late Jim Gilliam from Dallas, in the 1970’s with his discovery of subacute cutaneous lupus erythematosus, showed dermatologists and rheumatologists the full spectrum of lupus from mild skin involvement to devastating multi-organ involvement. I do believe psoriasis also has a similar spectrum with an even more protean clinical manifestation than lupus, from a few minor patches or even purely skin involvement to devastating joint disease with or without other systemic immune-mediated diseases such as Crohn’s, diabetes, multiple sclerosis, etc plus aspects of the Metabolic Syndrome. A most important aspect coming out of this wonderful array of clinical photographs is, I believe, the need for all dermatologists to do a total body evaluation of the patient at each visit, as too often a cursory examination is done, or patients because of their natural shyness to expose the surface of their skin to the public frequently will not disclose to the dermatologist areas of concern, such as flexural psoriasis, genital and perianal involvement, etc. In addition, are the various different manifestations of nail psoriasis important as a marker for psoriatic arthritis as discussed in Chapter 6?|auteur215]

The clinical manifestations of psoriasis are varied. The elementary lesions are the result of all possible combinations of: epidermal proliferation and parakeratosis leading to the exaggerated formation of squamae, epidermal and dermal inflammation responsible for infiltration of the lesions but also for erythema and the formation of micropustules, and sometimes even clinically visible pustules. Consequently, the psoriasis plaques can take highly varied appearances, from simple erythema covered with light desquamation, to the characteristic erythematosquamous plaque, or even to the emergence of a carpet of pustules. Erythema and desquamation are thus the only anomalies to be constantly observed (photos 2 and 3).

The typical elementary lesion of psoriasis combines all these components and presents a papular, erythematosquamous rounded lesion that is well circumscribed and covered with micaceous, silvery-white scales (photo 4). Scratching these scales with a curette causes one last glossy squama to appear. If tugged at, a characteristic bloody dew connected to the abrasion of the turgescent dermal papillae starts to well up. Sometimes, one can observe a lighter halo, as described by Woronoff, surrounding the plaque. It is not known whether this is a sign of the plaque’s progression or, conversely, of an anti-inflammatory response by restricting the spread (vasoconstriction?).

[|Regarding the Woronoff ring, I
have only seen this sign in healing psoriatic plaques, close to their final
disappearance. I regard it as being caused by different propensity to be
stained to topical antipsoriatic drugs such as anthralin.|auteur195]

The body areas most often affected and often most resistant to treatment are the elbows (photo 5), the knees (photos 6 and 7), the scalp (photo 9) and the lumbar region (photos 8, 10 and 11).

But all body areas may be affected, even the mucosa. Each of the
possible sites may be associated with other sites, making its diagnosis
easier, or may be isolated, often making diagnosis more difficult
(photos 12 and 13).

Hence the descriptions: psoriasis of the scalp, psoriasis of the face (photo 14), psoriasis of the eyelids (photo 15), psoriasis of the external auditory canals (photo 16), psoriasis of the skin folds (photos 17 and 18)—also called inverse or flexural psoriasis, wherein the squamae are not observed due to maceration, psoriasis of the mucous membranes: lingual mucosae, with geographic tongue (photo 19), genital mucosae (photos 20 and 21), psoriasis of the nails (photos 26, 27, 28, 29 and 30) and palmoplantar psoriasis. Each site poses different differential diagnosis problems, has specific repercussions on the quality of life and raises particular therapeutic problems, which will be detailed.

[Depending on the surface of the plaques|In my view this
distinction is made on the size of the lesion rather than on its surface.|auteur195], we distinguish guttate psoriasis (photo 31) (guttate psoriasis), nummular psoriasis, generalized psoriasis – so-called universalis (photo 34) – in which a few sites of healthy skin persist, and finally erythrodermic psoriasis, affecting the entire skin area (photo 32). The shape of the plaques can also vary, some being annular with central clearing, with the rings potentially joining up to form circinate psoriasis (photos 33 and 35).

The extent of neutrophils migration in epidermis may lead to the formation of clinically visible pustules characteristic of pustular psoriasis (photo 36). The latter may be generalized, with pustules appearing on the plaques of classic psoriasis, as sometimes observed after stopping general corticotherapy, or generalized pustulosis, as described by von Zumbusch (photo 37). Pustular psoriasis may be localized: palmoplantar pustulosis (photo 38) and acrodermatitis continua of Hallopeau.

Depending on people’s age, psoriasis poses particular therapeutic problems. There can be psoriasis in the child (photo 39), psoriasis in the fertile woman and the pregnant woman (with this exceptional generalized pustular form, called impetigo herpetiformis) and psoriasis in the elderly. Comorbidities play, of course, an important role in the choice of therapeutic strategy. Their impact will be discussed when we come to look at different ways of organizing therapeutic strategies.

[ Pruritus is associated in 70% of cases. |Is that really true?? 30%?|auteur193] Two quite disparate situations need to be distinguished:

1. generalized pruritus leading to look for an associated atopic diathesis, contact eczema, scabies… , responsible for psoriasis eruption (Köebner’s phenomenon), or an epidermotropic psoriasiform lymphoma;
2. localized pruritus, often producing a habit of repetitive scratching and ending not only in a permanent Köebner’s phenomenon but also in an associated neurodermatitis that will need to be treated in its own.