Page 56 - LECTURE NOTES

Histopathologic features

- Hyperkeratosis with parakeratosis (presence of nucleated keratinocytes in the

stratum corneum due lack of maturation of cells since rapid transit time do not permit
normal maturation of cells). Reduced or absent granular layer.

- Acanthosis with elongation of rete ridges and a corresponding upward elongation of

dermal papillae.
- Infiltrate: Mononuclear in dermis and polymorphs in the upper epidermis forming

collections called ‘microabscess of Munro’.

- Upper dermal vasculature shows dilatation and tortuosity.

Types of presentations: the patients may present in a variety of ways with overlapping
features being not uncommon.

1. Chronic plaque psoriasis (psoriasis vulgaris). The commonest type of psoriasis,
presenting with typical plaques of psoriasis of the extensors surfaces like knee,

pretibial area elbows and trunk, back and scalp. The plaques stay for months to
years without progression that is why it is called stable plaque.

2. Guttate psoriasis (acute eruptive psoriasis). Generally uncommon but appears in

childhood and young adults. Acute eruption of drop-shaped lesions distributed
widely over the body. Usually it follows streptococcal throat infection.

3. Flexural psoriasis (psoriasis inversa): lesions are present over the flexors and
intertriginous areas (axilla, groin, umbilical region, inframammary folds) the lesions

may be moist and lack the typical scaling.

4. Generalized pustular psoriasis may occur as an explosive eruption of generalized
pustules with systemic disturbances. This may follow withdrawal of systemic steroid

therapy or application of irritants
5. Pustular psoriasis. May be localized or generalized. Localized pustular psoriasis

usually presents with persistent pustular eruptions of the hands and feet.

6. Erythrodermic psoriasis (more than 90% of the body surface area affected).
Psoriasis may present with Erythroderma (exfoliative dermatitis). There is

generalized inflammatory erythema with profuse scaling. The mortality is very high
without proper care( exfoliative dermatitis and it management)

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