Teenaged girl distressed by persistent rash

The case

A 16-year-old girl presents for evaluation of an asymptomatic brown rash over her central chest and back that developed over the preceding 6 months. She is embarrassed by the appearance.

Etiology

Confluent and reticulated papillomatosis (CARP), also known as Gougerot-Carteaud syndrome, is an uncommon papulosquamous eruption of unknown etiology. It has been hypothesized that CARP may result from a disorder of keratinization,¹ an endocrine imbalance,² or an abnormal immune response to bacteria or fungi.^3,4

Epidemiology

Usually, CARP affects adolescents and young adults.⁵ It is more common in females. It is typically sporadic, although familial cases have been reported.⁶

Clinical presentation

Typically CARP presents as hyperpigmented brown-to-gray hyperkeratotic papules that enlarge and coalesce to form plaques that are confluent centrally and reticulated peripherally. There may be overlying scale, and the eruption may have a velvety appearance.

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Whereas CARP usually involves the central chest and upper back, it may also affect the neck, upper arms, and axillae. It is generally asymptomatic, although it may be mildly pruritic. It may be associated with acanthosis nigricans (AN) and shares histologic features with AN. However, treatment and resolution of CARP does not affect the course of AN.

Diagnosis

Confluent and reticulated papillomatosis is diagnosed clinically. Proposed diagnostic criteria include: 1) presence of scaling brown macules and patches, at least part of which have a reticulated and papillomatous appearance; 2) involvement of the upper trunk and neck; 3) negative fungal staining of scales; 4) no response to antifungal treatment; and 5) excellent response to minocycline.⁵

Suggested modifications to these diagnostic criteria include the addition of flexural areas to the list of sites of involvement, and response to antibiotics in general, rather than minocycline specifically.⁷

Differential diagnosis

The differential diagnosis includes tinea versicolor, AN, Darier disease, and Dowling-Degos syndrome. In contrast to tinea versicolor, potassium hydroxide fungal staining is usually negative in CARP. Acanthosis nigricans typically presents with thicker, more velvety plaques lacking reticulation in intertriginous areas. Darier disease often involves the seborrheic areas of the face as well as the nails, which are usually not affected in CARP. Patients with Dowling-Degos syndrome often have pigmented comedones and pitted acneiform scars on the chin.

Treatment

The treatment of choice for CARP is 2 months of therapy with minocycline or doxycycline, which are effective in most patients.⁵ Other agents that have been reported to have variable efficacy include other topical and systemic antibiotics,^8,9 antifungals directed against Malassezia,¹⁰ topical and systemic retinoids,^11,12 and 70% alcohol swabbing.¹³

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Without treatment, most patients will improve spontaneously over months to years. Treatment is primarily for cosmetic purposes. The condition often has a chronic course marked by exacerbations and remissions, and may recur after stopping treatment.^5,14

Patient outcome

The patient was treated with 100 mg minocycline twice daily for 8 weeks, which led to resolution of the eruption on her chest and back. She remains free of recurrence.

REFERENCES

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2. Hirokawa M, Matsumoto M, Iizuka H. Confluent and reticulated papillomatosis: a case with concurrent acanthosis nigricans associated with obesity and insulin resistance. Dermatology. 1994;188(2):148-151.

3. Natarajan S, Milne D, Jones AL, Goodfellow M, Perry J, Koerner RJ. Dietzia strain X: a newly described Actinomycete isolated from confluent and reticulated papillomatosis. Br J Dermatol. 2005;153(4):825-827.

4. Yesudian P, Kamalam S, Razack A. Confluent and reticulated papillomatosis (Gougerot-Carteaud). An abnormal host reaction to Malassezzia furfur. Acta Derm Venereol. 1973;53(5):381-384.

5. 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.

6. Inalöz HS, Patel GK, Knight AG. Familial confluent and reticulated papillomatosis. Arch Dermatol. 2002;138(2):276-277.

7. Jo S, Park HS, Cho S, Yoon HS. Updated diagnosis criteria for confluent and reticulated papillomatosis: a case report. Ann Dermatol. 2014;26(3):409-410.

8. Jang HS, Oh CK, Cha JH, Cho SH, Kwon KS. Six cases of confluent and reticulated papillomatosis alleviated by various antibiotics. J Am Acad Dermatol. 2001;44(4):652-655.

9. Gönül M, Cakmak SK, Soylu S, Kiliç A, Gül U, Ergül G. Successful treatment of confluent and reticulated papillomatosis with topical mupirocin. J Eur Acad Dermatol Venereol. 2008;22(9):1140-1142.

10. Nordby CA, Mitchell AJ. Confluent and reticulated papillomatosis responsive to selenium sulfide. Int J Dermatol. 1986;25(3):194-199.

11. Schwartzberg JB, Schwartzberg HA. Response of confluent and reticulate papillomatosis of Gougerot and Carteaud to topical tretinoin. Cutis. 2000;66(4):291-293.

12. Lee MP, Stiller MJ, McClain SA, Shupack JL, Cohen DE. 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.

13. Berk DR. Confluent and reticulated papillomatosis response to 70% alcohol swabbing. Arch Dermatol. 2011;147(2):247-248.

14. Montemarano AD, Hengge M, Sau P, Welch M. Confluent and reticulated papillomatosis: response to minocycline. J Am Acad Dermatol. 1996;34(2 pt 1):253-256.