1.Tuberous xanthoma

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C. Xanthomas
Definition
Lipid-laden foamy histiocytes aggregate on the skin or mucous
membranes to form yellowish lesions. This condition usually
accompanies a systemic abnormality of lipid metabolism; however,
lipid abnormality is not found in all cases. Xanthoma is divided
by clinical features into several subtypes described below.
Pathology
Xanthoma presents histologically as aggregation of foam cells
in the dermis (Fig. 17.9). Touton giant cells may be found.
Treatment
Hyperlipemia should be treated first. Eruptive xanthoma may
disappear when the triglyceride level falls. However, cases with
nodules do not readily respond to oral drugs.
Fig. 17.9 Histopathology of xanthoma.
Foamy histiocytes that have phagocytosed fat
droplets are observed in the dermis.
1. Tuberous xanthoma
Embossed, firm, pinkish-yellow tumors of 5 mm to several
centimeters in diameter occur, mostly on the extensor surfaces of
the elbows and knees and on the joints of the hands and feet (Fig.
17.10). The condition accompanies hyperlipoproteinemia (type
IIa, type III, type V).
Clinical images are available in hardcopy only.
2. Tendon xanthoma
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This is a type of tuberous xanthoma. The Achilles tendons and
the tendons of hands, legs and knees become tumorous. It accompanies
hyperlipoproteinemia (type IIa).
3. Plane xanthoma
Almost flat or slightly elevated, yellowish lesions occur. They
may be accompanied by hyperlipoproteinemia (Fig. 17.11).
Fig. 17.10 Tuberous xanthoma on the metacarpophalangeal
joints and proximal interpharangeal
joints.
Redness is seen in some of the affected sites.
4. Xanthelasma palpebrarum
The inner canthus of the upper eyelids becomes flatly elevated.
This disorder often accompanies hypercholesterolemia (type IIa,
type III). About half of all cases are not accompanied by hyperlipoproteinemia
(Fig. 17.12).
Clinical images are available in hardcopy only.
5. Eruptive xanthoma
Multiple, small, yellowish papules of 5 mm in diameter or
smaller occur on the entire body. Eruptive xanthoma accompanies
hypertriglyceridemia (Fig. 17.13).
Fig. 17.11 Plane xanthoma that occurred
secondarily after chronic lymphedema on
the upper arm.
There are vaguely demarcated yellow plaques.

278 17 Metabolic Disorders
Clinical images are available in hardcopy only.
Clinical images are available in hardcopy only.
Fig. 17.12 Xanthelasma palpebrarum.
Flatly elevated yellow plaques occur on the inner canthus of the upper
and lower eyelids, accompanied by mild infiltration.
Fig. 17.13 Eruptive xanthoma.
D. Electrolytic disorders
1. Acrodermatitis enteropathica
Synonym: Zinc deficiency syndrome
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Clinical images are available in hardcopy only.
Clinical images are available in hardcopy only.
Clinical images are available in hardcopy only.
Fig. 17.14 Acrodermatitis enteropathica.
Outline
This is a zinc deficiency whose main symptoms are dermatitis,
alopecia and diarrhea.
The main types are a congenital type (autosomal recessively
inherited) and an acquired type that is caused by
administration of parenteral central venous nutrition or
excision of the digestive tract.
Erythema and erosion form on the distal portions of the
extremities, and on the genitalia and orifices (the periphery
of the eyes and mouth, nares, and auditory meatus),
presenting clinical features similar to psoriasis, seborrheic
dermatitis and cutaneous candidiasis.
Clinical features
Dermatitis tends to occur on sites that have mechanical pressure,
such as the distal portions of the extremities, the genitalia,
and the facial orifices (the periphery of the eyes and mouth, nares,
and auditory meatus; Fig. 17.14). Acrodermatitis enteropathica
begins with papules, small blisters, or erythema accompanied by
pustules, and progresses to erosion and crusts. Annular scaling is
clinically observed, resembling psoriasis, impetigo, seborrheic
dermatitis and cutaneous candidiasis. Nail deformity and perionychia
occur.
Alopecia occurs in almost all cases, appearing on the occipital
and temporal region of the head first and then spreading to the
entire scalp and eyebrows. Diarrhea and vomiting recur.
Pathogenesis
The congenital type of acrodermatitis enteropathica is autosomal
recessively inherited. It is caused by a mutation in the
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