Papulosquamous disorders are disorders that are circumscribed and scaly, they present with both papules and scales. Simply put, they are skin conditions characterised by red to purple raised scaly patches on the skin.
Examples of which are:
Pityriasis Rosea
Lichen planus
Psoariasis
This is is an acute exanthematous eruption with a distinctive morphology and often with a characteristic self limiting course.
Age of onset-
10- 43yrs (rarely occurs in infants and old persons).
Season
Spring and fall
Beginning of the Rainy season in Topical regions
Aetiology is unknown but the Herpes virus type 7 has implicated.
First, a single red and slightly scaly plaque develops usually on the trunk, called the Herald's patch.
Later (after 1 or 2 wks) a generalized secondary eruption develops in a typical distribution pattern; the entire process remits spontaneously in 6wks.
Pruritus (itching) may occur.
Lesions are usually confined to trunk and proximal aspects of the arms and legs, rarely on the face.
They are dull pink or tawny, oval, scattered with a characteristicteristic distribution with the long axes of the lesions following the lines of cleavage in a xmas tree pattern.
image showing Pityriasis Rosea
Spontaneous remission occurs in 6-12wks or less. Recurrences are uncommon.
This is a hereditary, autoimmune disorder of the skin with several clinical expressions and types.
The most frequent type is Psoariasis vulgaris, which occurs as chronic recurring, scaling papules and plaques.
Clinical presentation varies in individuals, from those with only a few localized plaques to those with generalized skin involvement.
Types
Age of onset
In children, the mean age of onset is 8years and adults presents about age 55.
Early age of onset predicts a more severe and chronic disease.
Aetiologic factors
Heriditary- Chances of having psoariasis is increased when both parents have it. HLA types most frequently associated with psoriasis are HLA-B13,B17,Bw57, and most importantly, HLA-Cw6.
Physical trauma (koebner’s phenomenon) is a major trigger or precipitating factor in eliciting lesions, rubbing and scratching stimulates the process.
Infections- Acute streptococcus infection precipitates guttate psoariasis.
Stress causes a flare of psoriasis.
Drugs such as steroids, oral lithium, antimalarial drugs, interferon and B adrenergic blockers can cause flares in existing psoariasis and cause a psoriasiform drug eruption.
When one or more of these aetiological factors are present it causes alteration of the cell kinetics of keratinocytes with a shortening of the cell cycle from 311hours to 36hours resulting in 28 times the normal production of epidermal cells.
There are two types of Psoriasis based on its features.
For Localized lesions
For generalised lesions
LP is an acute or chronic inflammatory dermatosis involving skin and/or mucous membranes, characterized by flat topped, pink to purple, shiny, pruritic polygonal papules on the skin and milky white reticulated papules in the mucous membranes.
The features of lichen planus have been described as the four Ps- Purple, Pruritic, Polygonal Papules.
Age of onset
30-60yrs
Sex
Females > Males
Race
Hypertrophic Lichen Planus is commoner in blacks.
The aetiology of lichen planus is idiopathic (unknown) in most cases but it is evident that Cell Mediated Immune plays a major role. This involves infiltration of lymphocytes such as CD8 and CD45Ro. Other causative agents includes:
Drugs such as gold salts, beta blockers, antimalarial, thiazide diuretics, furosemide, spirinolactone and penicillamine.
Metals like gold, mercury
Infections such as Hepatitis B and C virus.
The onset of LP could be Acute (days) or insidious (over weeks). Lesions last months to years, and could be asymptomatic or Pruritic.
Lesions in the Mucous membranes are painful (especially when ulcerated). The lesions are reticulate, erosive or ulcerative and affects the genitalia, causes scarring alopecia on the scalp and destruction of nail fold and nail bed.
While Skin lesions exhibit the 4Ps with white lines called Wickham’s striae.
Lesions can be grouped, linear, annular, or disseminated scattered and discrete when generalized.
Lichen Planus lesions exhibits koebner’s phenomenon.
In dark skinned individuals, post-inflammatory hyperpigmentation is common.
Sites of predilection- Wrists (flexor) lumbar regions, shins (thicker hyperkeratotic lesions), scalp, glans penis, mouth.
Lesion Morphology
For Localized Lesions
For Generalised Lesions
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