Confluent and Reticulated Papillomatosis

Updated: May 04, 2017
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: William D James, MD  more...
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Gougerot and Carteud originally described confluent and reticulated papillomatosis (CRP) in 1927 under the name papillomatose pigmentée innominée and later renamed it papillomatose pigmentée confluente et réticulée. [1, 2, 3] Confluent and reticulated papillomatosis was subsequently categorized as a new form of cutaneous papillomatosis and diagnostic criteria were established. Wise described the first case in the United States in 1937 and called it confluent and reticular papillomatosis. [4, 5] The existence of confluent and reticulated papillomatosis as a distinct entity was argued for many years because of the clinical and histologic similarities between confluent and reticulated papillomatosis and the different forms of acanthosis nigricans, but the disease is now generally accepted as a distinct entity.

Confluent and reticulated papillomatosis is a rare disease typically affecting young persons. Confluent and reticulated papillomatosis is characterized by grayish blue hyperkeratotic papules, usually located on the trunk. The lesions coalesce to form confluent plaques centrally and a reticular pattern peripherally. Confluent and reticulated papillomatosis may represent an endocrine disturbance, a disorder of keratinization, an abnormal host reaction to fungi or bacteria, a hereditary disorder, or a variant of amyloidosis. The eruption is chronic with exacerbations and remissions. Confluent and reticulated papillomatosis is responsive to treatment but frequently recurs after discontinuation of therapy.



Both electron microscopy studies and immunohistochemical analysis of lesions of confluent and reticulated papillomatosis support the concept of abnormal keratinocyte differentiation and maturation. These findings include an increased transition cell layer and increased lamellar granules in the stratum granulosum, along with increased involucrin, keratin 16, and Ki-67 expression. [6] Increased melanosomes in the stratum corneum probably account for the observed pigmentary changes.

Yeastlike spores were evident in 6 of 10 Lebanese cases, supporting a role for Malassezia furfur in the pathogenesis of confluent and reticulated papillomatosis. [7]




The frequency of confluent and reticulated papillomatosis internationally is unknown. It is considered to be rare.


Older reviews report confluent and reticulated papillomatosis being more common among blacks than other races, with a ratio of 2:1, but more recent surveys, including one survey of 90 cases, show a predominance in whites.


The proportion of women to men affected by confluent and reticulated papillomatosis has been reported to be as high as 2.8:1, but the ratio is probably closer to 1.4:1. The opposite is true in Japan, where confluent and reticulated papillomatosis is more common in men than in women. In one study of 10 Lebanese cases, half were of each sex. [7]


The onset of confluent and reticulated papillomatosis usually occurs shortly after puberty. The mean patient age at onset varies from 18.5-21 years, with a range of 5-63 years. Similarly, the average patient age at onset is 17.1 years in Japan, with a range of 3-30 years. In one study of 10 Lebanese cases, the mean age at diagnosis was 19 years. [7]



Confluent and reticulated papillomatosis is a chronic disease characterized by exacerbations and remissions. Discontinuation of successful therapy usually results in recurrence of the confluent and reticulated papillomatosis.