Dermatology - 香港醫學組織聯會

VOL.15 NO.11 NOVEMBER 2010
Practical Approach for “Eczema”
Dr. KK LO
FRCP, FHKCP, FHKAM (Med)
Specialist in Dermatology & Venereology
Eczema is the commonest diagnosis in the clinical
practice for both specialists and family doctors when
encountering patients complaining of skin problems.
Eczema is prevalent in a local students study.
It appears as an apparent simple and easy condition to
deal with but indeed it is one of the conditions that our
patients are often dissatisfied about the outcome of the
treatments. In this brief review, I describe my approach
to let family doctors having a more systemic and logical
approach to the management of this common skin
problem.
My approach to the management of eczema follows
to the convention of Western medicine. We shall
be able to make the accurate diagnosis by standard
clinical methods, namely: clinical history, physical
examination and investigations if needed. Having
an accurate diagnosis is a half-way success and the
subsequent management is divided into general and
specific treatments. General treatment is actually more
important though very often its emphasis is skipped by
both the clinician and our patients.
The terms eczema and dermatitis are regarded as
synonyms in clinical practice though dermatitis is
used more often for exogenous causes. Eczema is
derived from Greek, “ek” meaning out and “zein”
to boil. Eczema defines the superficial inflammatory
itchy skin problem though eczema may mean different
things to different people. There are different views on
eczema even among specialists and it is no wonder how
confusing our clients and colleagues do in our daily
practice. My approach to the diagnosis of eczema is
by exclusion. The difference between a specialist and
a family doctor may be just in the different length of
exclusion list of differential diagnoses (see table 1) in
making the diagnosis.
Eczematoid rash is characterised by an erythematous
scaly rash with an ill-defined border in different
phases, acute, subacute and chronic. Furthermore, it
is a dynamic rash in that it will gradually change its
configuration, size, shape and colour with time in terms
of days, weeks and months. It can remit and reappear
with a turnover time from days to months. However,
if a persistent (never remitted and stayed in the same
location) erythematous scaly rash presents for years, a
diagnosis of eczema is unlikely. Skin biopsy or referral
to a specialist to exclude other serious conditions
Medical Bulletin
Dr. KK LO
This article has been selected by the Editorial Board of the Hong Kong Medical Diary for participants in the CME programme of the Medical
Council of Hong Kong (MCHK) to complete the following self-assessment questions in order to be awarded one CME credit under the programme
upon returning the completed answer sheet to the Federation Secretariat on or before 30 November 2010.
of papulosquamous dermatoses (Table 1) must be
considered.
Table 1: Differential diagnoses of eczema
Common cutaneous conditions Additional cutaneous conditions
considered for exclusion by considered for exclusion by
family doctors
specialists
Various forms of Superficial
fungal infections
Various forms of psoriasis and
psoriasiform eruptions
Lichen planus and lichenoid
eruptions
Neoplastic conditions e.g.
Mycosis fungoides, Bowen
d i s e a s e , L a n g e r h a n s c e l l
histiocytosis
Chronic infections e.g. Hansen
disease, secondary syphilis
Autoimmune diseases e.g.
dermatomyositis, subacute lupus
erythematosus, pemphigus
foliaceous
Various forms of cutaneous Nutritional diseases e.g. zinc
d r u g e r u p t i o n s i n c l u d i n g deficiency, essential fatty acid
photodermatitis
deficiency, Pellagra (niacin
deficiency)
Others: pityriasis lichenoides,
pityriasis rosea, lichen striatus,
g l u c a g o n o m a s y n d r o m e ,
congenital immunodeficiency
e.g. Wiskott Aldrich syndrome &
DiGeorge syndrome
Just making an accurate diagnosis of eczema may not be
adequate professionally. We should have a very simple
classification of eczema so that we may communicate
with our clients more confidently though the treatment
and outcome may vary little. The classification of
eczema will vary from one specialist to another. Mine
is a simple one (Table 2). I divide eczema into two main
groups: exogenous (external factors may play a more
important role) and endogenous (constitutional factor of
the person is more important). The prototype examples
of exogenous eczema are irritant contact eczema and
allergic contact eczema. Usually, contact eczema starts
in some local contact sites of our skin and a meticulous
examination of the location may give the clues of
allergen or irritants. Irritant contact eczema is more
common and the different layman names of irritant
contact eczema of hands have indicated their common
occurrence in the community. A detailed history on
occupation, daily hobbies and interests is essential.
Allergic contact eczema is a type IV hypersensitivity
condition and can be confirmed by appropriate patch
tests with specific contact allergens though it may not
be easily available in common clinical practice. With
good substitution for avoidance of future contact with
the allergens or proper protection from the irritants, the
prognosis of exogenous eczema is good. However, we
should remind our clients not to forget the importance
of compliance to general advice and care of the skin
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