These are group of different skin diseases, which are due to abnormality in keratinization.

Disorder of keratinization is due to a defect in keratin metabolism.

In the normal epidermis, as the keratinocytes move from the basal-cell layer to the surface, the process of terminal differentiation and cornification involves complex metabolic changes.

Different syndromes, which are related to abnormal keratinization, include:

/ السمك داء ماسى رده دهICTHYOSIS

Ichthyosis is a group of disorders that are characterized by a persistent, non-inflammatory scaling disorder of the skin surface.

Types of icthyosis

Genetic icthyosis

Acquired icthyosis

Icthyosis vulgaris The common type is an autosomal dominant skin disorder appearing in the first months of life. The entire skin surface shows abnormal desquamation, but the degree of scaling is worse on the extensor surfaces, particularly the legs.

The condition is worse in wintertime and with progress of child’s age, but some adults may survive normally.

Some cases of icthyosis are associated with atopic dermatitis.

Two types of inherited icthyosis are known; the autosomal dominant and the recessive X- linked

Icthyosis Vulgaris

Clinical Manifestations

Mild form shows slight roughening and dryness of the skin.

Skin manifestations present with follicular keratotic lesions, where orifices are plugged by horny debris showing follicular ‘spines‘ as well as dry scaly skin on the back of hands.

 HistopathologyEpidermis: Hypertrophic and hyperkeratotic.Thick granular layer.

Treatment

Emollients should be used regularly to relieve the dryness and itching and to decrease the tendency to skin fissuring.

Preparations containing urea and 2 per cent salicylic acid in a suitable vehicle for severe skin

scaling .

Care should be taken into consideration when using topical salicylic acid in children due to the possibility of toxic absorption.

X-Linked Recessive Icthyosis

This type is an X-linked recessive trait affects male children in the family only.

Clinical Manifestations

Large scales covering the neck, face, ears and the flexural surfaces as the axilla, the ante cubital and popliteal areas. The scalp is scaly.

X-linked recessive Icthyosis

Treatment:

Some reports showed good improvement of scaling by using 12% ammonium lactate containing lotions.

The retinoids group of drugs may give good improvements, but the side effects limit their use in infants and young children and may be reserved for severe reluctant cases in older age groups.

Antihistamines may be needed in the presence of itching.

LAMELLAR ICTHYOSIS

This disease begins usually at birth and is inherited as an autosomal recessive trait.

Clinical Features:*Quadrilaterally shaped large grayish brown scales, free at

the edges and adherent in the center .The areas involved in mild cases are the antecubital,

popliteal and the neck .

*The palms and soles may present with mild hyperkeratosis. The follicles have a crateriform

appearance .

*Ectropion

HistopathologyHyperkeratosisHyper grannulosisProminent rete ridgesMild perivascular infiltrate in the upper dermis and mitosis.

TreatmentEmolients Improvement may be achieved by 0.1 percent Vitamin A.

ICTHYOSIFORM ERYTHRODERMA(Collodion baby)This is a rare severe type of icthyosis present at birth of unknown etiology and has a high mortality rate. It is believed that lamellar exfoliation of the newborn (collodion baby) is a form of lamellar icthyosisClinical FeaturesSkin manifestationsInfants may be born with a distinctive, tough, inelastic collodion-like membrane covering their bodies. The constricting membrane produces a peculiar position of immobility of the limbs and causes ectropion of the eyelids.

The membrane eventually fissures and peels. If the baby survives, the membrane is shed, usually to reveal a more characteristic ichthyosiform abnormality beneath. Uncommonly, normal skin is found beneath the collodion membrane.

General Features

Affected infants appear very ill, dehydrated and in danger of hypothermia

HARLEQUIN FETUS

HARLEQUIN FETUSThis is a more severe form of the collodion baby disorder affecting the skin in utero and causing thick, horny, armor-like plates that cover the entire skin surface. There is usually stillbirth or early death after delivery.

This very rare type may have other systemic manifestations. The disease is usually fatal within the first month of life.

Clinical FeaturesThe skin is dry, hyperkeratotic and fissured.

The abnormal inelastic skin, resulting in ectropion and small-deformed ears grossly deforms the facial features.

KERATOSIS PILIARIS

Keratosis pilaris is a common disorder that is inherited as an autosomal dominant in childhood and reaches its peak incidence in adolescence.

This disorder leads to keratinous plugs in the follicular orifices with varying degrees of perifollicular

erythema                                            .

Clinical Picture:The lesions appear as small gray to white plugs of keratin that obstruct the mouths of the follicles entrapping the hair. The sites of predilection are the extensor surfaces of the upper arms, thighs and buttocks. Some follicles are completely spared while adjacent ones are grossly plugged showing a long strand of keratin protruding when examined in light (antenna sign).

FOLLICULAR KERATOSIS(Lichen spinulosus)

 Follicular keratosis is a disease of abnormal keratinization that appears in childhood. The skin lesion presents with grouped follicular papules occluded by a projecting keratinous spine. The commonest sites involved are the extensor surface of the extremities, thighs and abdomen.

A number of skin disorders may give rise to similar skin lesions mainly lichen planus and seborrheic dermatitis.

Acquired Keratinization Disorders

ACQUIRED ICTHYOSIS

Acquired icthyosis has the same skin manifestations as the other types but it is caused by different diseases.

The syndrome may be associated with other manifestations such as anhidrosis, malabsorption and liver diseases.

The diagnosis of an itchy icthysiform skin lesion in infancy or early childhood should exclude the possibility of Hodgkin‘s disease.

The different diseases that have icthysiform manifestations besides the other manifestations are:

)SLE (Systemic lupus erythematosus

Hodgkin‘s disease.

Malignant diseases

Nutritional deficienciesDrug reaction as a reaction to medications used for lowering cholesterol.

PITYRIASIS RUBRA PILIARIS

Pityriasis rubra piliaris (PRP) is a chronic inflammatory disease characterized by fine acuminate, horny, follicular papules that affects both sexes equally and occurs at any age.

EtiologyThe cause of the disease is unknown. The essential abnormality appears to be epidermal over activity. Genetic factors have been considered since the disease is transmitted as an autosomal dominant trait.

CALLOSITIESCallosities represent variants of abnormal keratinization, which are more common in adults.

The condition may be congenital or acquired.

Callosities may appear early in young age as a familial type or may be acquired in response to repeated trauma or friction as by tight shoes over the bony prominence of the palms or soles. The most common site is over the head of the third metatarsals where the lesion may be mistaken as skin wart.

Corns may show a central degenerative core in the middle of dense hyperkeratosis, which should be distinguished from the black thrombotic vessels of the verruca (warts).

TreatmentMild callosities respond to local application of salicylic acid (20%) and lactic acid (20%) in collodion base for few days. Before each application the dead tissues can be removed by shaving.

Extensive cases can be resurfaced by CO2 laser.

ACANTHOSIS NIGRICANS

Acanthosis nigricans is an inherited genodermatosis that is characterized by hyperkeratosis and skin pigmentation. The affected skin is covered by papillomatous elevations, which give it a velvety texture.

Clinical Features

There are different clinical types of acanthosis nigricans:

1-The benign type:

affects children and may appear after birth .

Skin lesions are scaly, dry, gray brown or black patches that are thickened and covered by small papillomatous elevations giving the velvety texture of the lesions.

The disease resembles ichthyosis and is not associated with endocrine disturbances

or internal malignancy .

There is skin thickening and the skin lines are further accentuated. The surface becomes mammillated and larger warty excrescencies may develop. The intertriginous areas show warty lesions where the lesions may become generalized and cover an extensive areas of the skin surface.

2-The malignant type: occurs in adults and older age groups. This type is very rare in children .

The skin lesions are rapidly progressive with involvement of the mucous membranes, which are useful warning signs.

3-The pseudo acanthosis type: is a common type that appears after puberty and may be associated with

hypertrophic ostearthropathy .

Palmoplantar Keratoderma• This is an inherited disease of abnormal keratinization affecting

infants and young children.• Clinical Features• Skin manifestations• Redness and thickening of the palms and soles simulating

psoriasis.• General manifestations• Hyperhidrosis that may cause an unpleasant odor.• Hair is usually normal but may be sparse.• Frequent pyogenic infections.• Periodontosis resulting in severe gingivitis that may predispose to

loss of the teeth . The permanent teeth may be lost in the same fashion.

• Dural calcification, especially in the attachment of the tentorium and choroid, has been noted in some cases.

KERATODERMAS DUE TO OTHER DERMATOSES

Different skin diseases may give rise to palmoplanter hyperkeratosis.

These include:

Psoriasis. Hyperkeratosis of the palms and soles are associated with the characteristic psoriatic lesions with

the silvery scales .

Reiter‘s disease. The lesions are compact, heaped up and resemble the heads of nails (keratoderma

blenorrhagica) .

Pityriasis rubra pilaris ..

Eczema

Lichen planus .

Viral warts in immuno-compromised patients may be confluent on the palms or soles .

Hyperkeratosis due to dermatophytes (fungal skin infections).

Syphilis. Syphilis may involve the palms and soles leading to hyperkeratosis. Hyperkeratotic lesions of late syphilis

may be very warty or focal .

Arsenic ingestion: causes multiple, irregular warty keratoses .

Drugs. Occasional lesions of keratoderma are seen following ingestion of medications such as iodine. In these cases the ‘keratoderma‘ peels off in a continuous

sheet within days or weeks .

 

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