Diagnosis: Confluent and reticulated papillomatosis
This patient was given a diagnosis of confluent and reticulated papillomatosis (CRP) based on the clinical presentation.
Although this condition is uncommon,1 we see it at least once a month in our dermatology clinic. CRP is characterized by centrally confluent and peripherally reticulated scaly brown plaques and papules that are cosmetically disfiguring.1
CRP usually is asymptomatic2 and primarily affects young adults—especially teenagers.3 It occurs in both males and females3 and it commonly occurs on the trunk.1,2
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
Differential diagnosis includes acanthosis nigricans
Acanthosis nigricans (AN) shares similar “dirty” brown, confluent textural plaques, as well as nonspecific acanthosis and papillomatosis on histopathologic examination. However, AN affects flexural areas, whereas CRP typically is found on the epigastrium, central chest, and central back.1,2
Tinea versicolor (TV) and CRP are both brown in color, and occur in a similar distribution on the central back and chest.4 However, in contrast to the fine perifollicular scaling seen in TV, CRP is associated with textural, confluent plaques. TV also can be distinguished by its pathognomonic “spaghetti and meatball” pattern of hyphae and spores on potassium hydroxide (KOH) preparation; KOH will be negative in patients with CRP. When a presumed case of TV does not respond to antifungal therapy, CRP should be considered.1