Erythrodermic psoriasis (EP) is another dermatological emergency; those who experience EP usually have pre-existing CPP. The usual characteristics of CPP disappear as EP progresses; the skin becomes generally inflamed with no noticeable plaques and there is generalised exfoliation (Figure 8.7). Trigger factors include emotional stress, response to systemic illness and alcoholism; however, the most noticeable cause of EP is the inappropriate use of potent steroids (topical, oral and injectable). Like GPP, EP is potentially life threatening and the patient will need to be hospitalised for intensive nursing care.
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| Figure 8.7 Erythrodermic psoriasis. (Source: Reprinted from Weller et al., 2008.) |
The various variants of psoriasis may be confused with other skin diagnoses. Table 8.1 lists the common confusions.
| | | | | | Table 8.1 Differential diagnoses for psoriasis. | | Type of psoriasis | Key clinical features | | May be confused with | | | Chronic plaque psoriasis | Clear demarcation between psoriatic skin and normal skin
Extensive scaling
Pin-prick bleeding
Appears on extensor surfaces | | Nummular eczema
Lichen simplex chronicus | | | Guttate psoriasis | Rain drop type lesions on trunk and arms Often follows a throat infection | | Pityriasis rosea | | | Inverted psoriasis | In flexural areas
Bright red
Shiney
Clear edge | | Fungal infection | | | Nail psoriasis | Pitting of the nail plate
Hyperkeratosis of the nail bed leading to thickened nails and lifting of the nail plate | | Fungal infection of the nail
Ageing nails which will thicken especially if subject to trauma | | | Erythrodermic psoriasis | Generalised erythema
Exfoliation
History of chronic plaque psoriasis | | Other causes of erythroderma, e.g. drug reaction, eczema | | | | | | | |
