DISCUSSION
This is a fairly typical case of confluent and reticulated papillomatosis (CRP), also known as Gougerot-Carteaud syndrome. CRP is rare, mainly affecting young adults with darker skin after puberty. It can manifest in both genders. Originally believed to be a variant of acanthosis nigricans, CRP is now considered a distinct diagnostic entity.
At first glance, the appearance of CRP mimics that of TV. But the rough feel, reticular look, and dark color of CRP (which results from an increase in melanosomes) are totally missing in TV. Histologic studies of CRP show abnormal keratinocyte differentiation and maturation, a picture markedly at odds with that of TV.
TV, a result of the commensal yeast organism Malassezia furfur (M furfur) metabolizing normal sebum and leaving behind azelaic acid, causes color changes in the skin. But M furfur is not involved in CRP, and therefore the condition does not respond to oral or topical antiyeast medications.
The most effective treatment for CRP is minocycline (100 mg bid for 10 d). Long-term treatment includes weight loss and reduction of ambient heat.
TAKE-HOME LEARNING POINTS
- Confluent and reticulated papillomatosis (CRP) affects the trunk and extremities of obese patients with darker skin.
- In contrast with tinea versicolor (TV), CRP has a rough texture and reticulated look, especially on the periphery of the involved areas.
- Biopsy can help distinguish CRP from its lookalikes; it shows abnormal keratinocyte differentiation and maturation, as well as increased melanosomes.
- Oral minocycline is the best treatment, along with weight loss and reduction of ambient heat.