A 17-year-old Black woman with obesity presents for evaluation of a rash on her posterior neck, abdomen, and back that appeared several months earlier. The patient first noted the rash on her neck; at the time, the condition was diagnosed as acanthosis nigricans. Laboratory workup revealed no abnormalities. The rash has remained asymptomatic but is of concern because of its unsightly appearance. The patient has a family history of diabetes. Examination reveals hyperpigmented papules and patches of the affected areas accompanied by a fine scale.
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Confluent and reticulated papillomatosis (CARP) of Gougerot and Carteaud is an uncommon skin condition that typically affects the upper body. The disease presents with hyperpigmented, hyperkeratotic macules and papules that coalesce into reticulated patches and plaques.1 Adolescents, young adults, women, and people of African American descent are the populations most affected by CARP.2 The etiology of CARP is unknown; possible causes include hereditary overexpression of keratin, bacterial infection, or metabolic dysfunction.1
The condition is a benign disorder that is usually asymptomatic or mildly pruritic. It is often misdiagnosed as tinea versicolor given the similarity in appearance and presentation on the same body parts, primarily the trunk.1 Both diseases can be associated with fine scale. Confluent and reticulated papillomatosis can present with a velvety appearance leading to misdiagnosis of acanthosis nigricans.3 There is an increased prevalence of CARP in patients with obesity, polycystic ovary syndrome (PCOS), and diabetes mellitus.3 Cases of CARP and acanthosis nigricans occurring simultaneously have also been reported.1
Confluent and reticulated papillomatosis is usually diagnosed clinically. Absence of spores on potassium hydroxide (KOH) preparation rules out tinea versicolor. The first-line treatment for CARP is oral minocycline or another tetracycline.4 Oral antibiotic treatment can be supplemented with topical keratolytic agents such as lactic acid or topical retinoids. Oral retinoids are an alternative treatment option for patients with refractory cases.4
Brittany Spinosa-Weber, PA-C, is a physician assistant at DermDox Dermatology Centers in Bethlehem and Leola, Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. Basu P, Cohen PR. Confluent and reticulated papillomatosis associated with polycystic ovarian syndrome. Cureus. 2019;11(1):3956. doi:10.7759/cureus.3956
2. Xiao TL, Duan GY, Stein SL. Retrospective review of confluent and reticulated papillomatosis in pediatric patients. Pediatr Dermatol. 2021;38(5):1202-1209. doi:10.1111/pde.14806
3. Krishnamoorthy M, Nadler E, Vaidya S. Resolution of confluent and reticulated papillomatosis after bariatric surgery. Clin Obes. 2021;11(1):12427. doi:10.1111/cob.12427
4. Mufti A, Sachdeva M, Maliyar K, et al. Treatment outcomes in confluent and reticulated papillomatosis: a systematic review. J Am Acad Dermatol. 2021;84(3):825-829. doi:10.1016/j.jaad.2020.08.133