Baboon syndrome

Overview

Baboon syndrome, medically known as Symmetrical Drug-Related Intertriginous and Flexural Exanthema (SDRIFE), is a rare type of drug eruption characterized by a symmetrical red rash, primarily affecting the buttocks, groin, and flexural areas. The name "baboon syndrome" comes from the reddish appearance of the buttocks that resembles those of a baboon. Unlike other drug reactions, this condition is not accompanied by systemic symptoms such as fever or malaise and typically appears after systemic exposure to a sensitizing agent in someone previously sensitized through contact.

Causes

Baboon syndrome is triggered by systemic exposure to certain medications or substances in individuals who have already been sensitized via skin contact. Common causes include:

• Antibiotics (especially beta-lactams like penicillin and amoxicillin)

• Nonsteroidal anti-inflammatory drugs (NSAIDs)

• Chemotherapy agents

• Contrast media used in imaging procedures

• Metal exposure (e.g., nickel or mercury in dental fillings)

The reaction is considered a type IV hypersensitivity reaction and requires prior sensitization to the triggering agent.

Symptoms

Baboon syndrome presents with a distinct set of skin findings:

• Symmetrical, sharply demarcated erythema on the buttocks, groin, and sometimes axillae and inner thighs

• Lack of systemic symptoms such as fever, joint pain, or general malaise

• Pruritus (itching) may be present but is often mild

• No mucosal involvement, which helps distinguish it from more severe drug reactions like Stevens–Johnson syndrome

The rash usually develops within hours to a few days after exposure to the causative drug.

Diagnosis

Diagnosis is clinical and relies on identifying the characteristic rash and history of drug exposure:

• Detailed drug history to identify recent or prior exposure to potential triggers

• Clinical examination showing symmetrical erythema in intertriginous and flexural areas

• Skin biopsy may be performed in unclear cases, showing non-specific dermatitis features

• Patch testing may help confirm the allergen in patients with recurrent episodes

Other causes of flexural rash, such as contact dermatitis or intertrigo, must be excluded.

Treatment

Management is straightforward and generally involves:

• Immediate withdrawal of the offending drug or substance

• Topical corticosteroids to reduce inflammation and redness

• Oral antihistamines for relief of itching

• Supportive skin care, including emollients and avoiding irritants

In rare, persistent or severe cases, short courses of systemic corticosteroids may be considered.

Prognosis

The prognosis of baboon syndrome is excellent:

• Rash typically resolves within a few days to a week after stopping the triggering agent

• No long-term complications are expected in most patients

• Recurrence is possible with re-exposure to the causative substance

Patients should be educated to avoid the offending agent in the future and inform healthcare providers of the allergy to prevent recurrence.