Drug reactions & principles of topical treatment

Question 1

Describe the management of pruritus

Answer 1

1. Identify and treat underlying disease.
2. Treat xerosis with baths and emollients.
3. UVB and narrow-band (311 nm) photother-
   apy or PUVA (in renal-, biliary-, aquagenic-,
   and polycythemia vera–related pruritus).
4. Topical agents: capsaicin, doxepin 5%, camphor/menthol, topical 3% aspirin solu- tion (helps with lichen simplex chronicus
   (LSC)), pramoxine, naltrexone cream 1%.
5. Oral agents: Naloxone, naltrexone (25–50 mg/d), or ondansetron; antihistamines, tri- cyclic antidepressants (decrease central itch perception), thalidomide (especially in HIV), low-dose gabapentin (start at 300 mg/d but may need to titrate up as high 2400 mg/d before deemed ineffective); cholestyramine in cholestatic itch (but ineffective in total
   biliary obstruction).

Question 2

Describe the algortihm in the management of pruritus

Answer 2

Initial Visit
1. Detailed history of pruritus:

• Are there any skin lesions that precede the itching?
• Is the itching continuous or does it occur in waves?
• Is the itching related to certain times of the day, does it occur at night, and does it keep the patient awake?
• Is the itching related to environmental conditions (heat, cold); is it related to emotional stress, physical exertion, sweating, contact with water?

2. Examine carefully for subtle primary skin disorders as a cause of the pruritus; xerosis or asteatosis, scabies, pediculosis (nits?). Discrete papules on elbows, scalp (dermatitis herpetiformis), on scrotum or shaft of penis (scabies).
3. Check for dermographism, rub skin for Darier sign (see “Mastocytosis Syndromes,” Section 20).
4. Repeat history related to pruritus. Obtain history of constitutional symptoms, weight loss, fatigue, fever,
   malaise. History of oral or parenteral medication that can be a cause of generalized pruritus without a rash.
5. General physical examination including all the lymph nodes; rectal examination and stool guaiac in adult patients.
6. If dry skin or winter itch is a reasonable possible explanation, give the patient bath oil, followed by an emollient
   ointment. No soap; the bath is therapeutic, not for cleansing the skin; shower to clean. 7. Follow-up appointment in 2 weeks

Subsequent Visit(s)
If no relief from symptomatic treatment given on the first visit, proceed as follows:
1. Detailed review of systems.
2. Laboratory tests: complete blood tests including erythrocyte sedimentation rate, fasting blood sugar, renal
function tests, liver function tests, hepatitis antigens, thyroid tests, stool and serologic examination for parasites. 3. If the diagnosis has not been established at this point, the patient should be referred for complete workup
including pelvic examination and Pap smear.

Question 3

Name causes of pruritus sine materla

Answer 3

CauSES Of PrurITuS SINE MaTErIa

Metabolic, endocrine conditions
Hyperthyroidism: probably due to increased blood flow
Hypothyroidism: probably due to excessive dryness
Pregnancy related
Diabetes: pruritus is rarely associated, but can be a symptom of diabetic neuropathy

Malignant neoplasms: can be the presenting feature Lymphoma, myeloid and lymphatic leukemia, myelodysplasia Multiple myeloma
Hodgkin disease
Other cancer (rare)

Drug ingestion
Subclinical drug sensitivities
Aspirin, alcohol, dextran, polymyxin B, morphine, Codeine, scopolamine, d-tubocurarine, Hydroxyethyl starch

Infestations/Infections Scabiesa
Pediculosis corporis, capitis, pubis Hookworm (ancylostomiasis) Onchocerciasis
Ascariasis
HIV: can be a primary symptom of infection or a chronic comorbidity

Renal disease
Renal failure: may develop prurigo nodularis, lichenification, or nummular eczema as a result of scratching

Hematologic disease
Polycythemia vera: seen in up to 50% of patients upon contact with water Paraproteinemia, iron deficiency

Hepatic disease
Obstructive biliary disease: pruritus starts acrally and then disseminates Pregnancy (intrahepatic cholestasis) (see Section 15)

Psychogenic states Transitory:
Periods of emotional stress Persistent:
Delusions of parasitosis Psychogenic pruritus Neurotic excoriations Anorexia nervosa

Latent dermatoses and miscellaneous conditions Xerosis (dry skin, “winter itch”)
Senile pruritus: very common in people >70 years Bullous pemphigoid (without skin lesions) Dermatitis herpetiformis (without skin lesions) Atopic dermatitis (without skin lesions)
Factitious urticaria (dermographism)
Fiber glass exposure
Aquagenic pruritus: usually in middle aged and elderly, provoked by contact with water of any temperature,
lasts up to 1 hour. Different condition from senile pruritus or bath itch from polycythemia. Histamine levels
are elevated in blood.
Notalgia paresthetica: interscapular is most common location; likely due to neuropathy secondary to entrapped
spinal nerves as they emerge through the muscle fascia of the back (Fig. 35-2).
Brachioradial pruritus: localized pruritus of outer surface of upper arm, elbow and forearm superimposed on
chronic sun damage (golfer’s itch).

Question 4

Define pruritus related to xerosis/ rf/ tx

Answer 4

• Itching in areas of dry, scaly skin
• Severe xerosis may precipitate eczematous dermatitis
• Risk factors include advanced age, frequent bathing, ambient high temperatures and low humidity
• Use of mild cleansers, routine use of moisturizers
• Avoidance of excessive and aggressive skin washing
• Non-sedating antihistamines

Question 5

Name Primary dermatologic conditions associated with pruritus

Answer 5

• Eczematous dermatitis (atopic dermatitis, contact dermatitis,…)
• Urticaria
• Papulosquamous disorders (psoriasis, lichen planus,…)
• Infections and infestations (dermatophyte infections, scabies, pediculosis…)
• Scars

Question 6

Describe what to do in the following case:
* 66 year-old male
* Chronic renal failure-10 years
* Itching all over the body-2 years

Answer 6

Renal Pruritus
* Common among dialysis patients
* Consider other dermatologic and systemic causes of pruritus
* Optimal dialysis
* Optimal treatment of hyperparathyroidism, hyperphosphatemia,
hypermagnesemia
* Emollients/topical analgesic agents
* nb-UVB
* Gabapentin, pregabalin

Question 7

What should be asked when taking history from a patient with generalized pruritus without primary lesions?

Answer 7

• Duration
• Severity
• Aggravating/alleviating factors (temperature, water contact, chemicals…) * History of thyroid disorders, liver disease, renal disease, HIV, malignancy) * Constitutional symptoms (fever, weight loss, night sweats, weakness,…)
• Medications!
• Travel history
• Psychiatric and substance abuse history
• Pruritus in other household members
• Occupation, hobbies
• Complete physical examination!
• Lymph node examination!
• Initial lab tests: * CBC
• Serum bilirubin, transaminases, ALP * TSH
• BUN, creatinine
• Additional tests are based upon the patient history and suspicion for an underlying disorder