August 2015 Dermatology Clinic
A 14-year-old Hispanic male presents with a three-month history of a slowly enlarging “rash” on his chest and back. He denies associated pain or pruritus. The patient is overweight but has no known medical problems otherwise and takes no medications. Examination of the rash reveals gray-brown macules that coalesce into a large patch involving the chest, intermammary cleft, shoulders, and midline back. There is a reticular pattern and smaller satellite macules present at the peripheral margins. Aside from a few excoriations over the upper back, the remainder of the examination is unremarkable.
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Confluent and reticulated papillomatosis (CARP) is a distinct dermatologic condition of unknown etiology that affects both males and females of all races.1 It is more commonly seen in individuals with darker skin. The typical age of onset is during puberty or young adulthood.1 While most cases are sporadic, some familial cases have been reported.2
Several theories have been proposed regarding the cause. CARP has been postulated to be a skin manifestation of an underlying endocrinopathy, given its similar clinical appearance to acanthosis nigricans (AN) and its association with obesity, impaired glucose tolerance, diabetes mellitus, thyroid disorders, and pituitary disorders. However, many patients with CARP are otherwise disease-free.1 It has also been suggested to be a disease of keratinization due to its histological features and reports of successful treatment with retinoids.3,4 Cases of CARP that are responsive to topical ketoconazole have also been reported, suggesting that it may be an abnormal host response to environmental fungi, such as Malassezia furfur; however, fungal proliferation has not been demonstrated consistently.1,5,6 Finally, some researchers have hypothesized that CARP is a reaction to bacterial infection, given its responsiveness to various antibacterial agents, especially minocycline and azithromycin, although no single bacterium has been implicated consistently across reports.1,7
Clinically, CARP presents as small macules or papules that initially appear on the upper chest, upper back, or epigastric region and then enlarge to 4 mm to 5 mm in diameter with hyperpigmentation or hyperkeratosis. They eventually coalesce centrally and form a reticulated pattern peripherally. There may be associated pruritus, but the mouth and mucous membranes are never affected, as it remains limited to the chest, neck, shoulders, back, and abdomen.1,6-9
The differential diagnosis for CARP includes AN, pseudo-AN, tinea versicolor, prurigo pigmentosa, lichen planus pigmentosus, pityriasis rubra pilaris, and Darier disease, among other conditions that are more rare.1-9 CARP can be differentiated from these other conditions both clinically and histologically. AN has thicker, velvety plaques involving the intertriginous areas without peripheral reticulation. Similarly to CARP, pseudo-AN is more common in individuals with darker skin, but pseudo-AN disappears with weight loss due to its association with weight gain. Tinea versicolor and CARP may both have an association with M. furfur and a similar distribution pattern, but unlike a tinea versicolor lesion, CARP produces no fine scale when rubbed. Prurigo pigmentosa, in contrast to CARP, contains a variety of inflammatory cells on histology. With regard to any other similar conditions, CARP can be distinguished by the following features: lack of associated findings indicating systemic disease, negative tests for fungus,1,9 papillomatosis and club-shaped epidermal rete ridges on biopsy with minimal inflammatory infiltrates, hyperkeratosis,6,9 and response to treatment with minocycline.1,7-9
Various antibiotics have proven effective in reports of CARP,8 but minocycline and azithromycin have the best track record, with oral minocycline effective in at least 50% of patients. Recurrence of disease has been reported after cessation of antibiotics.1,7-9 Azithromycin, given its better side effect profile and lower pregnancy risk category, may be preferred as initial therapy in some patients.1 Should antibiotic therapy fail, suitable second- and third-line agents include topical ketoconazole,5 topical tretinoin,10,11 topical tazarotene,3 and high-dose oral isotretinoin.4 Oral retinoids should be avoided as initial therapy due to their adverse side effect profile that includes hypertriglyceridemia and teratogenicity.
The patient in this case was prescribed minocycline at 100 mg by mouth twice daily for three months. The condition had completely resolved at his follow-up appointment three months later.
Eman Bahrani, BA, is a medical student and Jennifer Ruth, MD, is a dermatology resident at Baylor College of Medicine in Houston.
- Scheinfeld N. Confluent and reticulated papillomatosis: A review of the literature. Am J Clin Dermatol. 2006;7(5):305-313.
- Açikgöz G, Hüseynov S, Ozmen I, et al. Confluent and reticulated papillomatosis (Gougerot-Carteaud syndrome) in two brothers. Acta Dermatovenerol Croat. 2014;22(1):57-59.
- Bowman PH, Davis LS. Confluent and reticulated papillomatosis: Response to tazarotene. J Am Acad Dermatol. 2003;48(5 Suppl): S80-S81.
- Lee MP, Stiller MJ, McClain SA, et al. Confluent and reticulated papillomatosis: Response to high-dose oral isotretinoin therapy and reassessment of epidemiologic data. J Am Acad Dermatol. 1994;31 (2 Pt 2):327-331.
- Hamaguchi T, Nagase M, Higuchi R, Takiuchi I. A case of confluent and reticulated papillomatosis responsive to ketoconazole cream. Nippon Ishinkin Gakkai Zasshi. 2002;43(2):95-98. Available at www.jstage.jst.go.jp/article/jjmm1990/43/2/43_2_95/_article
- Tamraz H, Raffoul M, Kurban M, et al. Confluent and reticulated papillomatosis: Clinical and histopathological study of 10 cases from Lebanon. J Eur Acad Dermatol Venereol. 2013;27(1):e119-e123.
- Chang SN, Kim SC, Lee SH, Lee WS. Minocycline treatment for confluent and reticulated papillomatosis. Cutis. 1996;57(6):454-457.
- Jang HS, Oh CK, Cha JH, et al. Six cases of confluent and reticulated papillomatosis alleviated by various antibiotics. J Am Acad Dermatol. 2001;44(4):652-655.
- Davis MD, Weenig RH, Camilleri MJ. Confluent and reticulate papillomatosis (Gougerot-Carteaud syndrome): A minocycline-responsive dermatosis without evidence for yeast in pathogenesis. A study of 39 patients and a proposal of diagnostic criteria. Br J Dermatol. 2006;154(2):287-293.
- Noh TW, Kang YS, Lee UH, Park HS. Topical tretinoin treatment for confluent and reticulated papillomatosis. Korean J Dermatol. 2012;50(11):937-944.
- Schwartzberg JB, Schwartzberg HA. Response of confluent and reticulate papillomatosis of Gougerot and Carteaud to topical tretinoin. Cutis. 2000;66(4):291-293.
All electronic documents accessed on August 4, 2015.