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
ƒ asteatotic dermatitis (“winter itch” due to dry skin)
ƒ pruritus of senescent skin (may not have dry skin, any time of year)
ƒ infestations: scabies, lice
ƒ drug eruptions: ASA, antidepressants, opiates
ƒ psychogenic states
• dermatologic – local
ƒ atopic and contact dermatitis, lichen planus, urticaria, insect bites, dermatitis herpetiformis
ƒ infection: varicella, candidiasis
ƒ lichen simplex chronicus
ƒ prurigo nodularis
• systemic disease – usually generalized
ƒ hepatic: obstructive biliary disease, cholestatic liver disease of pregnancy
ƒ renal: chronic renal failure, uremia secondary to hemodialysis
ƒ hematologic: Hodgkin’s lymphoma, multiple myeloma, leukemia, polycythemia vera,
hemochromatosis, Fe deficiency anemia, cutaneous T-cell lymphoma
ƒ neoplastic: lung, breast, gastric (internal solid tumors), non-Hodgkin’s lymphoma
ƒ endocrine: carcinoid, DM, hypothyroid/thyrotoxicosis
ƒ infectious: HIV, trichinosis, echinococcosis, hepatitis C
ƒ psychiatric: depression, psychosis
ƒ neurologic: post-herpetic neuralgia, multiple sclerosis