This patient was given a diagnosis of confluent and reticulated papillomatosis (CRP) based on the clinical presentation.
CRP is characterized by centrally confluent and peripherally reticulated scaly brown plaques and papules that are cosmetically disfiguring.1 CRP is usually asymptomatic and primarily impacts young adults—especially teenagers.2,3 It affects both males and females and commonly occurs on the trunk.1-3 CRP is believed to be a disorder of keratinization. Malassezia furfur may induce CRP’s hyperproliferative epidermal changes, but systemic treatment that eliminates this organism does not clear CRP.3
A CRP diagnosis is made based on clinical presentation. The eruption usually begins as verrucous papules in the inframammary or epigastric region that enlarge to 4 to 5 mm in diameter and coalesce to form a confluent plaque with a peripheral reticulated pattern. CRP can extend over the back, chest, and abdomen to the neck, shoulders, and gluteal cleft. CRP does not affect the oral mucosa, and rarely involves flexural areas, which differentiates it from the similar looking acanthosis nigricans.2 Although most cases are asymptomatic, mild pruritus may occur.1,2
A skin biopsy is rarely necessary for making a CRP diagnosis, but histopathologic findings include papillomatosis, hyperkeratosis, variable acanthosis, follicular plugging, and sparse dermal inflammation.1,3
Systemic antibiotics, most commonly minocycline 100 mg bid for 30 days or doxycycline 100 mg bid for 30 days, are safe and effective for CRP.1,4 Sometimes treatment is extended for as long as 6 months. Although CRP usually responds to minocycline or doxycycline, it is believed that this is the result of these drugs’ anti-inflammatory—rather than antibiotic—properties.1,2,4 Azithromycin is an effective alternative therapy.2,4 There is a high rate of recurrence of CRP in patients after systemic antibiotics are discontinued.2 Uniform responses to treatment and retreatment of flares have solidified the belief that antibiotics are an effective suppressive (if not curative) therapy despite a lack of randomized controlled trials.4
This patient was treated with minocycline 100 mg bid. After 1 month, the rash had improved by 70%. At 3 months, it was completely clear, and treatment was discontinued.
This case was adapted from: Sessums MT, Ward KMH, Brodell R. Cutaneous eruption on chest and back. J Fam Pract. 2014;63:467-468.