GENODERMATOSES DR. HADAF ABDULAMIR

ICTHYOSES A group of disorders where the homeostatic mechanism of epidermal cell kinetics or differentiation is altered, resulting in scales. Of many types, the most common of which are the vulgaris & the x -linked types. The clinical differentiation between them is difficult.

Differentiation 1) inheritance. 2) incidence 3) onset. 4) scales. 5) sites. 6) associated features. 7) prognosis. 8) treatment.

NEUROFIBROMATOSIS Autosomal dominant. Developmental changes in nervous system, bone,& skin. Of 7 types: type1( 85% of cases). Type2: bilateral acoustic neuroma. Type3 (mixed) & type 4 (variant) Type 5(segmental), type 6 ( only café au lait), & type7(late onset).

The cutaneous manifestations 1) neurofibromas: variable size, color, may be delayed till puberty, increasing in no. & size with age, anywhere, 90% of women have areolar neurofibromas.. 2) café au lait macules: 6 or more of 1.5 cm. dia. Is diagnostic, brownish, may pres. at birth & almost always by 1 year. 3) axillary freckling( crowe’s sign): extending to the neck, also genital, inguinal & perianal areas.

Other manifestations of NF 1) Eye changes: Lisch nodules in 95% of adult patients. 2) endocrine disorders as acromegaly, cretinism, myxoedema. 3)bone changes: as lordosis, kyphosis, pseudoarithrosis. 4) C.N.S.: as mental deficiency , dementia & epilepsy. 5) Increased cancer susceptibility.

TUBEROUS SCLEROSIS (=EPILOIA) EPI for epilepsy Lo I for low intellegence A for adenoma sebaceum Autosomal dominant of variable penetrance. Multiple hamartomas of skin, C.N.S., kidney, heart, retina & other organs.

Cutaneous manifestations 1)Ash-leaf macules: in 85%of patients, hypopigmented, leaf shaped, linear, or confetti like, no. 1-100, present at birth, randomly distributed. 2)Adenoma sebaceum (angiofibroma): in 90% of patients older than 4 years, 1-3 mm in size, symmetrical, on cheeks, nose & forehead waxy, translucent, yellowish-red papules, may inc. in no.

Cutaneous manifestations 3)Shagreen plaque (collagenoma): in 40% of patients in 1st decade of life, patch of irregular, knobby skin on trunk, 1-8cm in dia., mostly lumbosacral area. 4)Periungual fibromas( Koenen tumors): In 50% of patients starting at puberty, asymptomatic, small, protruding, digitate, periungual or even subungual.

General manifestations 1) C.N.S. : mental deficiency, epilepsy, seizures, tumors like glioma,astrocytoma 2) ophthalmological: phakomas. 3) renal tumors. 4) bone changes: as bone cysts. Treament: removal of adenomas by shaving, dermabrasion, & laser.

Epidermolysis bullosa A group of rare genetic disorders where blisters occur in response to minor physical injury. According to level of blistering divided into 3 main types: 1) intraepidermal. 2) junctional. 3)subepidermal.

Epidermolysis bullosa simplex Autosomal dominant with complete pen. Vesicles, bullae & milia at site of trauma as joints of hands, elbows, knees &feet, Start at birth or shortly after, few lesions. Mucus membrane & nails are spared Nikolisky sign is nagative. Worse in summer. Keratin gene mutation with abnormal intermediate filaments, fragile basal cells

Junctional epidermolysis bullosa( Letalis) Rare, autosomal recessive, lamina lucida sep. Starts at birth with sometimes fatal denudation of the skin within months. Generalized blistering, perioral & perinasal granulation tissue. No scarring or milia on healing but erosions persist for years. Bronchial & laryngeal involvement may cause resp distress & death If survive growth retardation & ref anaemia.

DYSTROPHIC EPIDERMOLYSIS BULLOSA Both dominant & rec. types, defective gene encoding for collagen 7 Blisters on extensors esp. joints . Nails may be thickened, Nikolisky often + Healing by scar, atrophy & milia. Mucus membrane involved with hoarseness of voice. Nail dystrophy, partial alopecia, contractures, claw hand & phalangeal bone atrophy. Cleavage in basal lamina.

TREATMENT Prevent trauma Decompress large blisters Treatment of infection In junctional we use epidermal autografts of cultured keratinocytes. In dystrophic: autologus meshed spli-thickness skin grafts & cultured keratinocytes may be used for non-healing skin defects.