A 20yo man complains of recent onset of itching which followed a viral infection. There are
numerous wheals of all sizes on his skin particularly after he has scratched it. These can last up
to an hour. What is the most probable dx?
a. Uremia
b. Urticaria
c. Psychogenic itching
d. Atopic eczema
e. Primary biliary cirrhosis
answer B
DD urticaria
Drugs: especially ASA, NSAIDs
Foods: nuts, shellfish, eggs, fruit
Idiopathic (> 2/3 of patients)
Infection
Insect stings (bees, wasps, hornets)
Percutanous absorption: cosmetics, work exposures
Stress
Systemic diseases: SLE, endocrinopathy, neoplasm
DD pruritis
• dermatologic – generalized
asteatotic dermatitis (“winter itch” due to dry skin)
pruritus of senescent skin (may not have dry skin, any time of year)
infestations: scabies, lice
drug eruptions: ASA, antidepressants, opiates
psychogenic states
• dermatologic – local
atopic and contact dermatitis, lichen planus, urticaria, insect bites, dermatitis herpetiformis
infection: varicella, candidiasis
lichen simplex chronicus
prurigo nodularis
• systemic disease – usually generalized
hepatic: obstructive biliary disease, cholestatic liver disease of pregnancy
renal: chronic renal failure, uremia secondary to hemodialysis
hematologic: Hodgkin’s lymphoma, multiple myeloma, leukemia, polycythemia vera,
hemochromatosis, Fe deficiency anemia, cutaneous T-cell lymphoma
neoplastic: lung, breast, gastric (internal solid tumors), non-Hodgkin’s lymphoma
endocrine: carcinoid, DM, hypothyroid/thyrotoxicosis
infectious: HIV, trichinosis, echinococcosis, hepatitis C
psychiatric: depression, psychosis
neurologic: post-herpetic neuralgia, multiple sclerosis
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