FS09.8 Drug‐induced Baboon syndrome: SDRIFE at strife with systemic contact dermatitis?

Abstract

The term baboon syndrome was introduced 20 years ago. It was proposed for a particular eruption mimicking the red gluteal area of the baboon after systemic exposure either to the contact allergens nickel and mercury or to oral ampicillin. Previously this phenomen was e.g. termed flexural exanthema to mercury. Since then similar incidences have been reported after systemic exposure to betalactam antibiotics and other drugs, sometimes under different terms. Clinically sharp demarcation of a V‐shaped erythema is present in inguinal/genital and gluteal/perianal areas. Additionally papules, vesicles and hemorrhagic lesion may be found. In most patients presence of exanthema in other anatomical flexural regions (axilla, elbow, knee, ventral neck) has been identified. However, involvement of the plantar/palmar regions, face and mucosal sites has not been documented. Typically blood tests are normal and systemic symptoms are absent. Histological results vary but a predominance of superficial perivascular infiltrate with mononuclear cells has been reported. Occasional positive patch tests or stimulation of lymphocytes in the LTT may be suggestive for a type IV allergic reaction. Since the drug‐related baboon syndrome shows clinically and histologically different findings to systemic contact dermatitis and acute generalized exanthematous pustulosis (AGEP), it should be seen as a separate entity. The mainstay for the diagnosis of systemic contact dermatitis requires contact sensitization and elicitation by a contact allergen. In contrast in the baboon syndrome and AGEP history for sensitization is often negative, although sometimes positive patch and LTT results can be found. AGEP, on the other hand, requires a distinct score including systemic signs and leucocytosis. In all three symptoms typically occur within 1 to 2 days. The term baboon syndrome does not reflect the whole range of symptoms and signs. And, although it is easily remembered, the comparison to an animal may be insulting. Therefore, we suggest that drug‐induced baboon syndrome should be separated from the contact allergen‐induced form, and should be recognized as a separate entity within the spectrum of drug eruptions. For this reason we propose the acronym SDRIFE (symmetrical drug related intertriginous flexural exanthema). This refers to the distinctive clinical pattern of this drug eruption without implicating any pathomechanism, which has not been clearly elucidated. The following criteria are proposed: 1) Exposure to a systemically administered drug, 2) Sharply demarcated erythema of the gluteal/perianal area and/or V‐shaped erythema of the inguinal/perigenital area, 3) Involvement of at least one other intertriginous/flexural fold, 4) Bilaterally or symmetrically affected areas, and 5) Absence of systemic symptoms and signs.