Page 134 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-49 Integumentary System

Clinical manifestations

MYXEDEMA Characteristic facies
in myxedema:
coarse features;
thick lips; dry skin;
Myxedema is seen in patients with untreated severe puffy eyelids;
hypothyroidism. This condition results from a total dull, lethargic
lack of thyroid hormone secretion and resultant deposi- expression;
tion of mucopolysaccharides into the skin and other coarse hair
organs. Many skin and systemic findings are present
in severe hypothyroidism. This is a condition seen in
adults. The infantile form, called cretinism, is still
found in parts of the world that do not routinely test Megaloglossia,
newborn infants. If it is left untreated, mental retarda- showing dental impressions
tion and various neurological deficits can occur. Adult
myxedema is an uncommon clinical disease.
Clinical Findings: Patients usually develop severe
hypothyroidism slowly. It can be caused by autoim-
mune thyroiditis, a thyroid tumor, a pituitary tumor
or infarction, or hypothalamic disease. It can also be
seen after treatment of hyperthyroidism with improper
replacement of thyroid hormone. The onset of symp-
toms begins as mild, nondescript findings and advances Pudgy hands; chipped
to severe clinical disease as the lack of thyroid hormone nails; dry, wrinkled skin;
worsens. Patients have many constitutional sym ptoms hyperkeratosis of elbow
and always complain of fatigue, cold intolerance, and
a generalized malaise. Constipation and weight gain
are almost universal. Some patients develop a peri- Hypothyroidism
cardial effusion and bradycardia. Neurological reflexes
are blunted, and patients complain of slow mental Hair dry, brittle
reflexes. Lethargy, memory impairment,
The skin findings are specific to myxedema and can slow cerebration
help one make the diagnosis. Patients develop diffuse, Edema of face and eyelids (psychoses may occur)
nonscarring alopecia. The hair is often dry and breaks
easily. The lateral half of the eyebrows is shed. Finger- Sensation of coldness Thick tongue, slow speech
nails become brittle and lift off the nail bed. The facial Deep, coarse voice
features appear lethargic. Periorbital edema is promi- Diminished perspiration
nent. Dry skin is severe and can mimic ichthyosis vul- Heart enlarged, poor heart
garis. The skin on the lips is thickened, as is the tongue. Skin coarse, dry, scalding, sounds, precordial pain
The tongue may enlarge to the point that the impres- cold (follicular keratosis), (occasional)
sion of the teeth is seen on its lateral edges. If the yellowish (carotenemia)
infiltrate of mucopolysaccharides is extreme, the scalp Hypertension (frequently)
can become thickened and furrowed, taking on the
appearance of cutis verticis gyrate. The skin may Pulse slow
acquire a subtle yellow hue due to carotinemia; this is
most likely to be observed on the glabrous skin.
Laboratory findings are diagnostic and necessary. Ascites
A nonspecific mild anemia is seen, consistent with
anemia of chronic disease. Hypercholesterolemia and
hyponatremia are two of the nonspecific findings. Elec- Weakness
trocardiography shows bradycardia and a prolonged Menorrhagia (amenorrhea
PR interval. The results of various thyroid hormone may occur late in disease)
tests are characteristic. An elevated level of thyroid-
stimulating hormone (TSH) is confirmatory for a diag-
nosis of primary hypothyroidism. Thyroxine (T 4 ) levels
are low and can be measured in various ways.
It is critical to differentiate adult generalized Reflexes, prolonged recovery
myxedema, as seen in hypothyroidism, from pretibial
myxedema. Pretibial myxedema is a marker for hyper-
thyroidism, not hypothyroidism.
Pathogenesis: Thyroid hormone is required for mul-
tiple metabolic pathways to work properly, including
the breakdown of glycosaminoglycans. When there is a within the dermis. Hyaluronic acid makes up the Supportive care is necessary until the patient can be
decrease or a total lack of thyroid hormone, glycosami- majority of the mucin deposits. The alopecia is adequately stabilized. Determining the cause of the
noglycans cannot be properly metabolized, and they nonscarring. hypothyroidism is necessary to probe for thyroid
accumulate in the subcutaneous tissue, most promi- Treatment: Prompt recognition and diagnosis of cancer, pituitary problems, or other hypothalamic
nently in the tissue of the face and scalp. This leads to myxedema is required. It is a fatal condition if disease. Prompt recognition of the skin manifestations
the characteristic skin findings in myxedema. left untreated, and myxedema coma is precipitated and referral to an endocrinologist can be life-saving.
Histology: Biopsy specimens of involved skin show by a total lack of thyroid hormone. Thyroid replace- Once proper thyroid replacement has been achieved,
mild deposition of mucin between collagen bundles ment with levothyroxine (synthetic T 4) is required. the skin and hair findings slowly resolve over time.

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