A child is presenting with erythmatous follicular papules on trunk. There are areas of normal skin within the lesions. There is thickening of Palms & soles. This child is suffering from -

Pityriaisis rubra pilaris is a rare chronic papulosquamous disorder characterised by 1. reddish orange scaly plaques 2.palmoplantar keratoderma 3.keratotic follicular papules etiology: unknown.sometimes autosomal dominantly in herited, hypovitaminosis A, HIV, hypogammaglobulinemia, staphlococcus are the predisposing factors. clinical features: 1.children <19 years and adults 40-60 years are commonly involved 2.small follicular pinkish yellow scaling papules coalese to form plaques. 3.reddish orange erythema is present 4.scalp: diffuse erythema and scaling 5. nutmeg grater - horny follicular papules on the back of proximal phalanges feel like a nutmeg grater 6.papules and plaques progress to erythroderma with islands of normal skin- nappes claires 7.palms and soles- hyperkeratosis with painful fissures with yellowish hue- PRP sandal histopathology- alternating ohokeratosis with parakeratosis in both veical and horizontal directions- Checker board pattern IADVL text book of dermatology, page 1020.