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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Disorders of keratinisation

Learning objectives
Lichenoid diseases
Ichthyosis
Keratosis pilaris
Pityriasis rubra pilaris
Darier’s disease
Activity

Learning objectives

Lichenoid diseases

Many skin diseases include the term ‘lichen’, which is thought to originate from a resemblance to the lichen that is found on trees.

Lichen simplex is a type of eczema and was discussed in the dermatitis section of this course. There are several other uncommon “lichen” conditions that will not be considered in this course.

Lichenoid histology refers to liquefaction degeneration of basal layer, dermal infiltration of inflammatory cells hugging the basal layer, colloid bodies (degenerating keratinocytes) and dermal melanin.

Lichen planus under low power
Low power view
Lichen planus histopathology with liquefaction degeneration
Liquefaction degeneration
Lichenoid histology

Idiopathic lichen planus has the following features:

Follicular lichen planus (lichen planopilaris) results in perifollicular erythema and scaling in the scalp and other hair bearing areas. It may or may not arise in association with non-follicular or mucosal disease.

Lichen planus
The ventral wrist is a typical site
Lichen planus
The shins is a common site
Lichen planus
Hypertrophic lichen planus
Lichen planus
Lacy-pattern in buccal mucosa
Lichen planus
Nail dystrophy
Lichen planus
Polygonal papules and plaques.
Note white streaks (Wickham’s striae)
Lichen planus

Treatment of lichen planus may include:

Erosive lichen planus affects the oral and/or genital mucosa. It may result in very painful ulceration and scarring.

Lichen planus Lichen planus Lichen planus
Erosive lichen planus

Lichenoid drug eruption has similar histology, and sometimes clinical appearance. More often there is a diffuse eruption of mildly irritable flat dry patches on trunk and limbs. Common causes include thiazides, anti-malarials, gold and ACE inhibitors.

Chronic graft-versus-host disease (GVHD) also has lichenoid histology. Arising more than 100 days after bone marrow transplantation, there are lichen planus-like papules and dermal sclerosis.

Lichen sclerosus is a common cause of vulval itching and soreness in menopausal women. Only ten percent of cases affect other sites or men. It is thought to have an autoimmune origin, with an extracellular matrix protein as antigen. On the vulva, perineum and perianal mucosa, it causes white plaques, atrophy, sclerosis (scarring), haemorrhage, blistering and ulceration. In children, it is often confused with the results of sexual abuse.

Lichen sclerosus
Axillary lichen sclerosus
Lichen sclerosus
Penile lichen sclerosus
(balanitis xerotica obliterans)
Lichen sclerosus
Vulval lichen sclerosus
in pre-pubertal child
Lichen sclerosus
Extensive vulval, perineal
and perianal disease
Hypertrophic lichen sclerosus
Hypertrophic lichen sclerosus
Perianal squamous cell carcinoma
Perianal squamous cell carcinoma
Lichen sclerosus

Patients with lichen sclerosus should be under the care of a dermatologist. Ultrapotent topical steroids are generally successful but should be used with caution because of potential adverse effects.

Ichthyosis

Ichthyosis refers to a group of disorders of keratinisation characterised by excessively dry and scaly skin (abnormal differentiation and desquamation of the epidermis). Genetic analysis is identifying the protein abnormality responsible in specific subtypes.

The most common types of ichthyosis are:

Autosomal dominant ichthyosis vulgaris

Autosomal recessive lamellar ichthyosis

X-linked recessive ichthyosis

Bullous ichthyosiform erythroderma

Acquired ichthyosis is the dry skin associated with cachexia and certain forms of cancer and lymphoma. It is also characteristic in heavy consumers of kava.

Ichthyosis vulgaris
Ichthyosis vulgaris
X-linked ichthyosis
X-linked ichthyosis
Hyperlinear palms in ichthyosis vulgaris
Hyperlinear palms in ichthyosis vulgaris
Bullous ichthyosiform erythroderma
Bullous ichthyosiform erythroderma
Bullous ichthyosiform erythroderma
Bullous ichthyosiform erythroderma
Acquired ichthyosis in kava drinker
Acquired ichthyosis in kava drinker
Ichthyosis

Treatment of ichthyosis requires regular application of emollients containing urea and/or lactic acid and the use of soap substitutes when bathing. Oral retinoids may be prescribed for severe cases.

Keratosis pilaris

Keratosis pilaris affects up to 50% of adolescents and may present from neonate to middle-age.

Keratosis rubra pilaris
Keratosis rubra pilaris
Keratosis pilaris faciei
Keratosis pilaris faciei
Keratosis pilaris
Follicular plugging
Keratosis pilaris

Keratosis pilaris rarely clears with treatment. Urea-containing emollients may soften the affected areas. Topical retinoids encourage normal follicular keratinisation with improvement in the appearance in some patients but may irritate.

Pityriasis rubra pilaris

Pityriasis rubra pilaris (PRP) is the name given to a group of rare skin disorders resulting in localised erythematous scaly plaques rather like psoriasis. However there is less scaling and prominent follicular involvement. Keratoderma of palms and soles is usual. Both juvenile and adult types may result in erythroderma.

Pityriasis rubra pilaris
Juvenile PRP
Pityriasis rubra pilaris
Palmar keratoderma
Pityriasis rubra pilaris
Follicular papules
Pityriasis rubra pilaris

Darier’s disease

An uncommon inherited disorder with disordered keratinisation, resulting in characteristic greasy reddish papules in scalp and trunk, palmar pitting and nail changes. The onset of skin lesions is generally during adolescence. Darier's may be complicated by sunburn, staphylococcal infection, and herpes simplex virus infection

Darier disease Darier disease Darier disease
Darier disease Darier disease Darier disease
Darier’s disease

Darier histology has the following features:

Darier histology
Low power view
Darier histology
Close-up
Darier histology

Activity

Review the molecular genetics of keratin disorders.

 

Page 9 of 9. End of course. Back to: Scaly skin diseases contents.

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Author: Hon Assoc Prof Amanda Oakley

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