Dermatology Made Simple : Skin lesions caused by Drugs

Skin lesions caused by Drugs

Drug Induced Vasculitis

Vasculitis is inflammation of blood vessels that can cause their complete occlusion or lead to leakage of blood components through the vessel wall.

The inflammation can affect any of the vessels in the skin including capillaries, venules, arterioles and lymphatics.

The chief drugs involved in causing vasculitis are as follows:

Thiazide diuretics

Thiouracil

Antibiotics

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Oral anticoagulants ( warfarin and coumarin).

 skin vasculitis

Mechanism of Drug Induced Vasculitis :

Both  cell mediated and humoral immunity are thought to play a role.

The most common encountered skin rash is non blanching purpura on the limbs.

Treatment involves:

Withdrawing the offending drug

Administration of systemic steroids

Erythema Multiforme:

Erythema multiforme (EM) is an acute, self-limited, and sometimes recurring skin condition that is considered to be a type IV hypersensitivity reaction associated with certain infections, medications, and other various triggers

The characterstic rash is called as  target lesions that involve elbows,face and palms.

These lesions have a central vesicle and are erythematous.

There may or may not be some systemic features associated with this rash  

  Erythema multiforme

Precipitating factors include 

Herpes simplex virus (HSV) 

Epstein-Barr virus (EBV)

Histoplasmosis

Mycoplasma

Erythema multiforme represents mild end of spectrum of skin conditons with Steven Johnson”s syndrome the severest.

Following is a list of medications that cause Erythema multiforme:

Barbiturates

Non-steroidal anti-inflammatory drugs

Penicillins

Sulphonamides

Phenothiazines  

Anticonvulsants.

Diagnosis

This is usually clinical but in case of doubt,skin biopsy is diagnostic that show on histology necrotic 

keratinocytes,lymphocytic infiltrate and blister formation

Management:

This is usually achieved by stopping the causative medication and applications of topical steroids

Erythema Multiforme  major may require hospital admission for supportive care

Oral antihistamines and/or topical corticosteroids may help relieve itching.

Following treatments t have been reported to help suppress recurrent Erythema Multiforme:

Antimalarial drugs eg hydroxychloroquine

Dapsone 100-150mg/d

Azathioprine 100-150 mg/d

Miscellaneous Drugs in Resistant cases:

Ciclosporin,

Mycophenolate mofetil

Photochemotherapy (PUVA)

Thalidomide