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caused by chronic poor hygiene.
Treatment
Cutaneous symptoms should be treated appropriately. If necessary, treatment for mental imbalance may be necessary with
cooperation from a psychiatrist.
Photosensitive diseases
1. Solar dermatitis, Sunburn
Erythema and blisters are produced by prolonged exposure to
sunlight (mainly UVB). Pathologically, sunburn cells (apoptotic
epidermal cells), epidermal spongiosis, edema in the dermal
blood vessels, inflammatory cellular infiltration, necrosis and
subcutaneous blistering are present. Erythema occurs several
hours after photoradiation on the exposed site, and it gradually
becomes edematous (Fig. 13.14). Solar dermatitis is most severe
12 to 24 hours after irradiation, after which it gradually resolves.
Exfoliation and pigmentation occur in several days. Pigmentation
is left after healing in some cases. Application of sunscreen is
helpful for prevention. Cold compresses and steroid ointments
are effective. When blistering is present, the same treatments as
those for burns are applied.
13
Clinical images are available in hardcopy only.
2. Photosensitive dermatoses
a
b
c
d
e
f
g
hOutline
i
j
k
l
m
n
o
p
q
● Photosensitive
Clinical images are available in hardcopy only.
a
b
c
d
e
f
g
h
Fig. 13.14 Solar dermatitis, Sunburn.
a: Solar dermatitis caused by sleeping for 3 hours
on the beach. Blistering is marked. The cutaneous symptoms are equivalent to those of firstdegree and second-degree burn. b: The normal
skin, which was under the swim trunks, differs
distinctly from the site with solar dermatitis,
which was sun-exposed.
dermatoses are cutaneous diseases that
are caused or aggravated by sunlight exposure.
● Both extrinsic factors (e.g., drugs) and intrinsic factors
(e.g., inherited diseases, metabolic disorders) may be
involved.
● They are caused by direct action of drugs (phototoxic
dermatitis) or by immunological mechanism (photoallergic dermatitis).
● Xeroderma pigmentosum is a hereditary photosensitive
p
q
j
i dermatosis
kthat is linduced
m by intrinsic
n
ofactors.
r
Pathogenesis
The two main causative factors of photosensitive dermatoses
MEMO
The skin is darkened by exposure to the sun. Oxidation of melanin
occurs in the epidermis (primary tanning), and there is enhanced production of melanin (secondary tanning).
Suntan
r
Photosensitive diseases / 2. Photosensitive dermatoses
195
Table 13.4 Main drugs that induce photosensitive dermatosis.
Drug Classification
Drugs
Psychoactive
Chlorpromazine, promethazine, diazepam, carbamazepin, imipramine
Muscle relaxant
Afloqualone
Antihistamine
Diphenhydramine, mequitazine
Antibacterial agent
Nalidixic acid, enoxacin, ofloxacin, ciprofloxacin, lomefloxacin, sparfloxacin, fleroxacin,
tosufloxacin, tetracycline, doxycyclin
Antifungal agent
Griseofulvin, flucytosine, itraconazole
Antiinflammatory
Ketoprofen, tiaprofenic acid, suprofen, piroxicam, ampiroxicam, actarit, diclofenac, naproxen
Antihypertensive agent
Hydrochlorothiazide, trichlormethiazide, meticrane, clofenamide, tripamide, metolazone,
furosemide, tilisolol HCl, pindolol, diltiazem HCl, nicardipine HCl, nifedipine, captopril, lisinopril
Antidiabetic
Tolbutamide, chlorpropamide, glibenclamide, carbutamide, glymidine sodium
Antipodagric
Benzbromarone
Antitumor agent
5-FU, tegafur, dacarbazine, flutamide
Lipid-lowering drug
Simvastatin
Prostatomegaly therapeutic agent
Tamsulosin
Photochemistry therapeutic agent
8-Methoxypsoralen, trioxypsoralen, hematoporphyrin derivative
Vitamin
Etretinate, pyridoxine, VB12
Antirheumatic
Sodium aurothiomalate, methotrexate
(Based on: Kamide R. Photosensitive dermatosis caused by extrinsic photosensitizing substance. In: Tamaoki K, editor. New Dermatology Vol. 16. Nakayama Shoten; 2003: 293-300).
Table 13.5 Classification of photosensitive dermatosis.
Classification
Cause
Drug
Extrinsic
photosensitive
dermatosis
Diagnostic name
Phototoxic dermatitis
Chapter 13
Photoallergic dermatitis
Chapter 13
Pellagra
Accumulation
Intrinsic
photosensitive of chromophore
Porphyria
in skin
dermatosis
DNA repair
defect
Described
in...
Xeroderma pigmentosum
(XP)
Chapter 17
Chapter 17
Chapter 13
Cackayne syndrome
Bloom syndrome
Decrease of
melanin
Albinism
Chapter 16
Phenylketonuria
Chapter 17
Unknown
Hydroa vacciniforme
Chapter 13
Solar urticaria
Chapter 13
Polymorphous light eruption
Chapter 13
Chronic actinic dermatitis
(CAD)
Chapter 13
are extrinsic chemicals and intrinsic factors (Tables 13.4 and
13.5). This section describes photosensitive dermatoses that are
caused by extrinsic factors. Extrinsic photosensitive dermatosis is
inflammation of skin caused by the excitation of chromophores
by daily exposure to radiation (mainly UVA). Chromophores
reach the skin either from outside (skin lotion, perfume, fruit
juice, tar) to induce photocontact dermatitis or from within the body
(drugs, food). The mechanisms of inflammation are phototoxic
Photosensitive drug
eruption
MEMO
In addition to phototoxic condition or photoallergy, drug intake may induce intrinsic
photosensitive diseases (e.g., porphyria, lupus
erythematosus).
13
196
13
Physiochemical Injury and Photosensitive Diseases
sunlight (UVA)
chromophores
②Chromophores convert
into photoallergens.
①Contact is made
with a causative
substance,
or there is
intake of
such substance.
photoallergens
③The photoallergens connect
with biologic proteins.
biologic proteins
④Macrophages and
Langerhans cells
phagocytose the conjugates
of photoallergens and
biologic proteins.
in the lymph nodes
or intradermal
area
intradermal area
lymph ducts
⑤The photoallergens in
macrophages and
Langerhans cells are
presented to T cells, and
sensitization occurs.
regional lymph nodes
13
①Macrophages
and Langerhans
cells recognize
photoallergens
themselves.
primary intake of causative
substance (sensitization)
②The photoallergens
are presented to
effector T cells,
causing
inflammation that
peaks 48 hours
after presentation.
secretion of various cytokines,
localized inflammation
secondary and further intake
of the causative substance
Fig. 13.15 Mechanism of photoallergic reaction.
Table 13.6 Phototoxic reaction and photoallergic reaction.
Phototoxic
reaction
Photoallergic
reaction
Incidence
May occur in
anybody
Immunologically
mediated (Type
IV) only
More than one
exposure to
agent required?
No
Yes
(the excited substance itself becomes toxic) and photoallergic
(the excited substance becomes an allergen that induces inflammation by immunoreaction) (Fig. 13.15, Table 13.6).
1) Phototoxic dermatitis
Outline
● Phototoxic
Onset of reaction hours to 1
after exposure to day
agent and light
24-72 hours
Dermatitis
Clinical features
Exaggerated
sunburn
Distribution
Sun-exposed Sun-exposed
skin
skin
Spread to
unexposed
areas?
No
Pathologic feature
Spongiosis,
Necrosis of
epidermal cell eczema
(sunburn)
Yes (possible)
Almost never Yes
Cross reaction
(sometimes)
caused by similar
compounds?
Amount of agent Large
required for
photosensitivity
Small
dermatitis may occur in anyone by the combination of a certain dose of drugs and sun exposure.
● It may occur even at the first irradiation (usually by UVA),
without any latency.
● The main causative drugs are psoralen, coal tar, thiazide
drugs, and tetracycline.
Clinical features
Sunburn-like symptoms are mainly seen. That is, erythema and
edema are followed by exfoliation and pigmentation. Perfume
may cause both allergic contact dermatitis and phototoxic dermatitis (Berloque dermatitis) on the neck, especially the sides.
MEMO
The skin comes into direct contact with the causative agent. Subsequent exposure to light of a certain wavelength causes photocontact
dermatitis. It is classified by onset mechanism as phototoxic or photoallergic.
Photocontact dermatitis
197
Photosensitive diseases / 2. Photosensitive dermatoses
Pathogenesis
Drugs that accumulate in the skin absorb light at a certain
wavelength. Exposure to light at that wavelength causes phototoxic dermatitis. Each drug affects a particular site.
1. A test substance is
adhered to the
back for 24 hours.
Treatment
Intake of the causative substance should be discontinued. Sunlight is avoided by sunscreen and a hat. The treatments are the
same as those for contact dermatitis.
2. Half of the patch
site is exposed to a
slightly smaller
amount of UVB
than for the first
MED exposure
(about 70% of
MED). If the
not
substance is not a
exposed
cause of
to UVB
photoallergic
dermatitis in the
patient, no skin
lesion or erythema
will appear.
exposed to
a small
amount of
UVB
2) Photoallergic dermatitis
Outline
● Photoallergic
dermatitis is photosensitive dermatitis that
is caused by a type IV allergy reaction, which is induced
by sun exposure after topical application or intake of a
drug.
● Erythema and blistering are the main symptoms.
● Chlorpromazine, thiazide drugs and oral antidiabetics are
the main causative drugs.
Clinical features
Erythema and serous papules occur on the sun-exposed site,
progressing to edema blistering, and erosion.
Pathogenesis
Chromophores that somehow attach to the skin react to exposure to light of a certain wavelength (mostly UVA, sometimes
visible light) to become allergenic, or they may convert into haptens, connect with biologic proteins and become photoallergenic.
After sensitization, the causative substance is re-exposed to light
when it reaches the skin surface, where it induces type IV allergic
reaction (Fig. 13.15). This reaction does not occur without sensitization; that is, inflammation is not caused by the first exposure,
nor does allergic reaction occur in everyone. A person who has
been sensitized is prone to light-induced inflammation even from
a minute amount of the substance.
Laboratory findings, Diagnosis
Photo-patch test: The test substance is patched as in the usual
patch test. The minimal erythema dose (MED) of the patient is
also determined. After 24 hours, half of the patch site is exposed
to a slightly smaller amount of UV than that of the first MED
exposure. The other half is left unexposed. The result is determined 48 hours after exposure (Figs. 13.16 and 13.17).
Photo-drug test: Application of the suspected drug is discontinued for at least 20 days. A normal dose of a test drug is applied
for 2 days. The diagnosis is photoallergic dermatitis if an eruption is produced by exposure to light.
3. The patch is
removed after 48
hours. The site is
examined after a
short time passes.
13
Fig. 13.16 Photo-patch testing.
60
50
40
70
30
80
20
90
10
100 mJ/cm2
Fig. 13.17 Determination of minimal erythema dose (MED).
UVB from 0 mJ/cm2 to 100 mJ/cm2 is irradiated
in increments of 10 mJ/cm 2 on areas of the
patient’s back where no eruptions have been produced. The MED in this case is 30 mJ/cm2.
198
13
Physiochemical Injury and Photosensitive Diseases
Treatment
Intake of the causative substance and sunlight exposure should
be avoided. The treatment is the same as that for contact dermatitis. A photosensitive disease called “persistent light reaction,”
which is categorized as a chronic actinic dermatitis (CAD), may
remain after discontinuation of the causative substance.
3. Solar urticaria
Clinical images are available in hardcopy only.
a
13
a
b
c
d
e
f
g
Clinical images are available in hardcopy only.
b
c
d
e
f
g
h
Definition, Pathogenesis, Clinical features
An allergen is intrinsically produced in skin by exposure to
light, against which type I allergy is induced. Several minutes
after light exposure (mostly the visible spectrum, but also UVA
and UVB in some cases), extremely itchy urticaria occurs; however, it disappears in several hours. Anaphylactic shock may be
p
q
j
h
i rare cases.
k
l
m
n
o
caused
in
Diagnosis, Examinations
Solar urticaria is generally diagnosed from the recurring eruptions caused by exposure to sunlight or to artificial light. However, wheals may be produced or aggravated by light shielding in
some cases; certain wavelengths in the light are thought to inhibit
wheals. In young patients, differential diagnosis from erythropoietic protoporphyria may be necessary.
i
j
k
l
m
n
o
p
q
r
Treatment
The patient is shielded from the sun, and antihistamines are
applied as a symptomatic treatment. PUVA treatment may be
performed as a desensitization treatment. Immunosuppressants
and plasma exchange have been reported to be effective in severe
cases.
Clinical images are available in hardcopy only.
4. Chronic actinic dermatitis (CAD)
b
c
d
e
f
g
h
i
Fig. 13.18-1 Chronic actinic dermatitis.
a: Intractable eczema presents as lichenified
plaques that progress slowly. b: The skin lesion
improved significantly after topical application of
tacrolimus for several months. c: The skin lesion
recurred after sun exposure.
Clinical features, Pathogenesis
Chronic actinic dermatitis (CAD) most frequently occurs in
pchangeq whoser main
j
k
l intractable
m
n eczematous
o
adult
males.
An
symptom is slowly progressing lichenoid plaques occurs on
exposed areas of the body and becomes chronic (Figs. 13.18-1
and 13.18-2). In some cases, the lesions progress to erythroderma, leading to cutaneous lymphoma-like subcutaneous nodules,
thickening of the skin, or facies leontina. It is hypothesized that
intrinsic antigens are produced by light exposure for some reason; however, the details of the onset mechanism are unknown.
Photosensitive diseases used to be called “persistent light reaction” “actinic reticuloid” or “photosensitivity dermatitis.” Now
these are categorized as forms of CAD.
r
199
Photosensitive diseases / 6. Hydroa vacciniforme
Pathology
Eczematous lesions are the main symptom of CAD. As CAD
progresses, lymphocytic infiltration and atypical cells are seen in
all dermal layers, and Pautrier microabscess-like lesions may
occur in the epidermis (actinic reticuloid).
Laboratory findings, Diagnosis, Treatment
The minimal erythema dose (MED) for UVB is greatly
reduced. The MED for UVA and visible light is also reduced in
some cases. For differential diagnosis, the skin is subjected to
repeated UVB exposure and if eczematous lesions appear then
the diagnosis is CAD. Topical steroids are helpful. Complete
a
b
c
light shielding is essential. Tacrolimus ointment is also useful.
Oral steroids and immunosuppressants are effective in severe
cases.
Clinical images are available in hardcopy only.
d
e
f
g
h
i
j
k
5. Polymorphous light eruption
Clinical features
Polymorphous light eruption occurs most commonly in
women between the ages of 10 to 30. Itchy erythema and papular
eruptions appear at sun-exposed sites. They become chronic and
tend to gradually worsen. The condition also worsens in summer
and subsides in winter.
Pathogenesis, Diagnosis
Polymorphous light eruption is thought to be an allergic reaca
bdiseases
c withd
tion to light. In practice, all photosensitive
unknown causes and without specific symptoms of other photosensitive diseases are considered to be polymorphous light eruption. It requires reconsideration as to whether it is an independent
disease.
6. Hydroa vacciniforme
Outline
● Hydroa
vacciniforme is a rare intrinsic photosensitive disease seen in infants.
● Blisters with concave centers form at sun-exposed sites
on the face and dorsa of the hands.
● Epstein-Barr viruses are involved. The disease resolves
naturally at puberty.
● Sun shading is important.
Clinical features, Pathogenesis
Hydroa vacciniforme first appears in infants 2 to 3 years of age
and resolves naturally at puberty. It occurs more often in males.
Erythema and blisters with concave centers are produced by
exposure to sunlight or UVB, and crusts form later on. These
Clinical images are available in hardcopy only.
e
f
g
h
i
j
13
k
Fig. 13.18-2 Chronic actinic dermatitis (CAD).
d, e: Chronic eczematous skin lesion accompanied by intense itching on the occipital region
and dorsum of hand of a man in his 50s. It worsened with exposure to the sunlight. Oral
cyclosporine improved it markedly.
l
200
13
Physiochemical Injury and Photosensitive Diseases
Clinical images are available in hardcopy only.
leave atrophic scarring when they heal. They mostly occur in the
face, auriculae, and dorsa of hands (Fig. 13.19). The lesions are
sensitive to light and tend to worsen in summer. When the EB
virus is involved, the condition may progress to lymphoma. The
onset mechanism is unknown, and hereditary predispositions are
not usually found. In cases with the involvement of the EB virus,
natural killer-cell lymphoma may develop.
Diagnosis, Examinations, Treatment
Hydroa vacciniforme is diagnosed by laboratory findings. The
symptoms may resemble those of porphyria; however, the porphyria level in hydroa vacciniforme is within the normal range.
Direct sun exposure is avoided. Sunscreen is helpful.
7. Xeroderma pigmentosum (XP)
Clinical images are available in hardcopy only.
Outline
● XP
13
Fig. 13.19 Hydroa vacciniforme.
Clinical images are available in hardcopy only.
Fig. 13.20 Xeroderma pigmentosum (group
D).
Pigmentation on the face of a woman in her 20s.
The cutaneous symptoms are mild.
occurs in persons with congenital failure in the DNA
repair process. The cells are easily damaged by UV.
Sunburn frequently occurs.
● All types are autosomal recessive inherited.
● A malignant tumor may occur as a complication with age.
● Complete shading of light is an effective treatment.
Classification, Pathogenesis
Patients with xeroderma pigmentosum (XP) have a congenital
failure in repairing and eliminating DNA that is damaged by UV
exposure. The failure results in severe photosensitive symptoms.
UV causes a replication fork bypass of a pyrimidine (thyminethymine) dimer.
XP is classified by unscheduled DNA synthesis (UDS), a classification index, into 8 subtypes: groups A to G, and a variant
group (Table 13.7). Group A is the severest, and the variant
group is the mildest. In the variant group, UDS is normal; however, there is failure in DNA modification after synthesis. Group
A and the variant group are the most frequently occurring in
Japan, together accounting for 80% of all XP cases. All groups
are autosomal recessive and occur in 1 person out of 100,000 to
1.5 persons out of 100,000. About 30% of patients with XP are
born from consanguineous marriages. The main genes responsible for XP have been identified (Chapter 29).
Clinical features
Abnormalities are not found at birth; however, intense and
delayed sunburn in 1- to 2-month-old infants may be recognized
as the onset of XP group A. Extremely intense and persistent
sunburn recurs on sun-exposed sites such as the face and dorsa of
hands and forearms. As sunburn recurs, the skin dries and
coarsens, presenting an unwashed appearance with ephelides-like
pigmented patches, exfoliation, hypopigmented macules and
201
Photosensitive diseases / 7. Xeroderma pigmentosum (XP)
Table 13.7 Comparison between types of xeroderma pigmentosum.
Severity of skin
manifestation
Neurological manifestation
Average age
of skin cancer
development
UDS (%)
Onset
Reduced
<5
Babyhood
Reduced
3-7
Babyhood
C
Normal
10-25
Babyhood
Severe
None
10.5
D
Reduced
25-50
Babyhood
Moderate
Sometimes
35.5
E
Reduced
40-60
Babyhood and infancy
Mild
None
41.0
F
Reduced
10-20
Early childhood
Mild
None
47.7
G
Normal
<25
Early childhood
Mild
Sometimes
32
Variant Normal
100
Early childhood (about 5 years old)
Moderate
None
41.0
Group
MED
A
B
Severe, carcinogenesis Appears at about 1 year old
telangiectasia (Fig. 13.20). Seborrheic keratosis, small tumors,
and ulcers occur in succession at the base of these lesions in
childhood. Basal cell carcinoma, squamous cell carcinoma, keratoacanthoma and malignant melanoma occur subsequently.
Eye symptoms such as photophobia, blepharitis, dacryorrhea,
and conjunctivitis occur in childhood and progress to ectropion,
blindness, and malignant tumor in the terminal stages. Progressive neurological symptoms occur 6 months after birth, leading
to articulatory disorder, gait disorder and intellectual impairment.
Disturbance in growth, such as dwarfism and spondyloschisis,
also occur.
Groups E, F, and G are often overlooked due to their mild
symptoms. The carcinogenic period is the third decade of life.
Eye symptoms and neurological symptoms are rarely found in
these groups. Nevertheless, cutaneous symptoms and neurological symptoms in some cases of groups E, F, and G closely resemble those found in group A (Fig. 13.21). In the variant group,
MED is almost normal, but ephelides gradually appears after
childhood. Although eye symptoms and neurological symptoms
are rarely seen, basal cell carcinoma or squamous cell carcinoma
occurs in adulthood.
9.2
Sometimes
Severe
MEMO
UDS (unscheduled DNA synthesis), a test for
xeroderma pigmentosum (XP), shows the
potential degree of recovery from DNA damage under UV exposure, expressed as a percentage compared to normal controls. Cells
are scattered in a petri dish and exposed to
UV. When cultured in [3H] thymidine solution, damaged DNA is repaired, and the cells
absorb [3H] thymidine. The amount of [3H]
thymidine is measured by autoradiography for
comparison with normal cases; patients with
XP have reduced UDS values.
UDS value
Clinical images are available in hardcopy only.
Laboratory findings, Diagnosis
XP diagnosis is confirmed by the MED level, DNA and RNA
syntheses after UV exposure, measurement of UDS, and gene
test.
Treatment
Sunlight should be thoroughly avoided by limiting outings in
daytime, wearing clothes that cover the body thoroughly, keeping
the hair long, wearing UV-screening eyeglasses, sticking UVscreening film on windows, applying shades to fluorescent
lamps, and applying sunscreen. Early detection and treatment of
cutaneous malignant tumor are important. Neurological disorders
are treated by regular listening-comprehension tests, speech training, and motor ability retention training.
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Fig. 13.21 Xeroderma pigmentosum (Group
F).
Basal cell carcinoma on the dorsum of the nose
of a man in his 20s.
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13