▶Confluent and reticulated papillomatosis (CARP) (also known as Gougerot-Carteaud syndrome) is an uncommon disorder of unknown cause.
■In the past it has been linked to insulin resistance, disordered keratinization, UV light, and an abnormal host response to the yeast Malassezia furfur.
■More recently, some have suggested that CARP may be the result of follicular infection with a type of corynebacterium. This association is intriguing because the organism implicated appears to be sensitive to tetracyclines and erythromycin.
▶CARP typically has its onset during puberty, and girls are affected more often than boys.
▶Most often, CARP occurs sporadically, but familial cases have been reported.
▶CARP presents as hyperpigmented patches and thin papules and plaques, most often involving the intermammary region, epigastrium, and upper back. The face, neck, and shoulders occasionally are involved.
▶Papules coalesce becoming confluent centrally and reticulated peripherally (Figures 124.1 and 124.2).
▶The eruption usually is asymptomatic, but mild pruritus may be present.
Look-alikes
Several eruptions are concentrated on the trunk and may mimic CARP. In none would the lesions typically have a rough surface or peripheral reticulation.
Disorder | Differentiating Features |
•Velvety thickening of the skin often located at the nape or sides of the neck and in the axillae. •Considered a marker for insulin resistance. | |
Tinea versicolor (hyperpigmented form) | •Lesions are hyperpigmented scaling macules that often coalesce into patches. •Reticulated appearance absent. |
•Typical lesions are oval thin plaques with long axes oriented parallel to lines of skin stress. •Initial larger lesion (“herald patch”) presents before the secondary smaller lesions. •Reticulated appearance absent. | |
Pityriasis lichenoides chronica | •Rash more generalized (not limited to the trunk). •Involvement of the buttocks is common. •Surface scaling with thin crusts common. •Reticulated appearance absent. |
▶The diagnosis is made clinically based on the typical appearance and distribution of the rash.
▶Treating CARP may be challenging because no treatment is universally effective and the eruption may recur following withdrawal of treatment.
▶Treatment with minocycline (or doxycycline) orally for 1 to 2 months is considered the most effective option. Some clinicians recommend adding a topical emollient containing α-hydroxy acids (most commonly lactic acid or ammonium lactate) to the treatment regimen.
▶Other treatments that have variable efficacy include topical selenium sulfide, topical or oral antifungal agents, and topical keratolytics alone.
▶The prognosis generally is good, although no treatment is universally effective and recurrences are possible.