Diagnosis: Confluent and reticulated papillomatosis
Confluent and reticulated papillomatosis (CARP), first described by Gougerot and Carteaud in 1927, typically presents as small hyperpigmented papules on the central back or chest. These small papules rapidly grow to become larger verrucous papules or coalesce into verrucous plaques. The plaques then merge to form a reticular pattern. CARP commonly occurs during puberty. It has a preponderance for women and blacks, being 2.5 times more common in women and twice as common in blacks.
The pathogenesis of CARP is unknown. Among the theories proposed are endocrine imbalance, a disorder of keratinization, and an atypical response to Pityrosporum orbiculare.1 However, none of these has been proven, and the majority of patients have no other abnormalities.
The histopathologic picture—hyperkeratosis, acanthosis, and papillomatosis—is not specific for CARP and, in the absence of any history, can be confused with that of epidermal nevus or acanthosis nigricans. Clinically, however, the three are distinctly different: the epidermal nevus being a solitary lesion and acanthosis nigricans being a more confluent hyperpigmentation. In some cases of CARP, a mild superficial perivascular lymphocytic infiltrate is seen.
The treatment of CARP can be very disappointing, even for the seasoned dermatologist. A multitude of treatments have proven unsuccessful. Even when CARP does respond, it often recurs after treatment is discontinued. Oral minocycline is frequently reported to be effective. One report of oral minocycline monotherapy demonstrated resolution without recurrences in 50% of patients and disease-free intervals as long as 18 months in others.2 Additional treatment options include topical salicylic acid, hydroquinone, oral and topical antifungals, 5-fluorouracil, isotretinoin, acitretin, and various other oral antibiotics.1
When counseling a patient who has CARP, be sure to discuss the difficulties encountered in management and the possibility of recurrence after treatment. Raising these issues up front will increase the likelihood of realistic expectations on the part of the patient.
A course of minocycline yielded a partial response that pleased my patient.
Dr. Harting is assistant professor of dermatology at the University of Michigan Medical School in Ann Arbor.
1. Pierson DM, Bandel C, Ehrig T, Cockrell CJ. Benign epidermal tumors and proliferations. In: Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. London, U.K.: Mosby; 2003: chap 110.
2. Chang SN, Kim SC, Lee SH, Lee WS. Minocycline treatment for confluent and reticulated papillomatosis. Cutis. 1996;57:454-457.