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Chapter 9: Erythematous lesions 389

Clinical features Clinical features
Most cases commence with a herald patch, a single Lesions are superficial hypopigmented macules appear-
salmonpinklesion2–5cmindiameterwithcentralclear- ing light brown or salmon coloured with a fine scale.
ing and peripheral scaling. Days later crops of similar They are most seen commonly on the upper trunk and
smaller oval plaques appear and proximal extremities. proximal limbs.
The lesions distribute along dermatomal lines, which is
most evident on the back appearing in a ‘Christmas tree’ Management
pattern. Treated with topical antifungal agents for 2 weeks. Oral
antifungalsmaybeusedforextensivedisease.Recurrence
is common, and frequent relapses may require prophy-
Management
laxis with topical selenium sulfide or an oral conazole.
Steroids and phototherapy may be of value for associated
The loss of colour in the skin may persist for several
itching.
months after treatment.
Prognosis Ichthyoses
Self-limiting. The condition fades in 1–2 months.
Definition
Theichthyosesaredisordersofkeratinisation,whichmay
Pityriasis versicolor be congenital or acquired characterised by a generalised
scaling of the skin due to hyperkeratosis (see Table 9.2).
Definition
Pityriasis (bran-like) versicolour (varying in colour) is
Management
achronic infection characterised by multiple macular
Topical emollients and bath additives are used to help
patches varying in size and degree of brown pigmenta-
avoid the dryness. Oral retinoids are used in the more
tion occurring on the trunk.
severe forms.
Aetiology
Caused by infection by the commensal yeast Pityrospo- Erythematous lesions
rumorbiculare (also known as Malessezia furfur, Pity-
rosporum ovale and Malassezia ovalis). Infection results
Erythema multiforme
from conversion of the yeast to the mycelial or hyphal
form, which may be triggered by heat and humidity and Definition
immunosuppression.Theyeastreleasescarboxylicacids, Aself-limiting hypersensitivity reaction affecting the
which inhibit melanin production. skin and occasionally mucous membranes.

Table 9.2 Forms of ichthyosis
Condition Inheritance Clinical features
Ichthyosis vulgaris Autosomal dominant 1 in 300, onset 1–4 yr, small bran-like scales are seen,
often mild
Sex-linked ichthyosis X-linked recessive 1 in 6000 males, generalised involvement with large dark
scales, onset before 1 year.
Lamellar ichthyosis Autosomal recessive 1 in 60,000, may at birth cause the collodion baby with
red scaly skin and ectropion, may resolve or progress to
other forms
Acquired ichthyosis Non-inherited Associated with inflammatory disorders, endocrine
anomalies, and neoplasia especially Hodgkin’s disease