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Case Reports

accentuation of rete ridges. Periodic Acid Schiff (PAS) staining of frozen sections shows characteristic cell membrane staining in stratum corneum, granular layer and basement membranes. PAS binds with glycoconjugates and staining is absent in normal skin and other ichthyosis except Netherton's syndrome. Kinetic studies using labeled thymidine shows increased epidermal turnover rate. Electron microscopy reveals abnormal lamellar bodies in stratum corneum.

Subtypes of autosomal recessive ichthyosis: 'Ichthyosis Congenita'

include: impairment of temperature regulation, increase insensible water loss through the skin, hypernatraemic dehydration, acute renal failure with and without brain damage and pneumonia due to restricted chest movement from the membrane and septicaemia. The severity of subsequent ichthyosis does not relate to collodion membrane. Larregue et al4 studied 198 cases of collodion babies and found that 60% developed NBIE, 35% developed lamellar ichthyosis, autosomal dominant ichthyosis, circumflex linear ichthyosis, Conradi syndrome, Sjogren-Larsson Syndrome and trichothiodystrophy, and 5% will eventually have normal skin (self-healing collodion baby).

German and Finnish groups have defined subtypes 1 to 4 of autosomal recessive ichthyosis congenita, based on ultrastructural findings, but these subtypes do not correlate well with the recognized clinical phenotypes and intra group variation also occurs (Table 1). They do, however, highlight the clinical, ultrastructural and possible heterogeneity of NBIE.1

Histopathology of collodion membrane

In contrast to retained periderm which is parakeratotic, the collodion membrane consists of compact, thickened orthokertatoic stratum corneum with otherwise normal epidermis and dermis. At birth collodion babies have identical clinical features and cutaneous histological features. Base on one case of self- healing collodion baby, Frenk suggested that it was possible to make a prediction of whether the child would develop a severe ichthyosis later in life on histological grounds at about Day 15.3 He described that the microscopic features observed were different from those known to occur in collodion babies evolving into lamellar ichthyosis.

Self-healing collodion baby

This refers to those with no subsequent disorder of cornification after shedding of collodion membrane. There were 10 cases reported in the last 20 years. It is difficult however to distinguish from those with mild forms of recessive ichthyosis. Based on five cases in a large Swiss kindred, Frenk found that all had consanguineous parents, autosomal recessive inheritance and all had shedding of collodion in the first month leaving slight scaling in few weeks.5

Treatment of collodion baby

This includes half-hourly applications of emollients, frequent oiling of skin, nursing in humidified incubator with careful temperature monitoring, aseptic handling, investigation and treatment of signs of sepsis and, meticulous fluid and electrolyte balance. Constriction bands if present should be divided.

Treatment of NBIE

Prognosis of collodion baby Possible complications during neonatal period

Emollients remain the mainstay of treatment. Prevention of sunburn and sunstroke is important. The risk of hyperpyrexia is increased by hypohidrosis and

Type Type 1 Type 2 Type 3

Ultrastructural features Lipid droplets in keratinocytes (non-specific) Cholesterol clefts in corneocytes, thinned cornified envelope

Clinical correlation Classical NBIE Lamellar ichthyosis, NBIE

Elongated membrane structures, abnormal lamellar bodies, lipid vacuoles in granular and corneal cells

Reticulated pattern lamellar ichthyosis, variable severity, not always collodion at birth

Type 4

Trilamellar membrane packages and vacuoles in granular and corneal cells

Atypical NBIE or lamellar ichthyosis

Table 1. Subtypes of autosomal recessive ichthyosis: 'Ichthyosis Congenita'

126 Hong Kong Dermatology & Venereology Bulletin

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