Discussion
CRP is a rare skin condition first described in 19272. It is asymptomatic in most of the times but can be pruriginous1. In 2006, Davis et al proposed five criteria for the diagnosis of the disease3, which were all displayed by our patient. CRP has been attributed for so long to the infection with Malassezia furfur1. However, as observed in our case, studies have been inconsistent with the detection of yeast in affected patients3. The currently admitted theory is that CRP is related to a bacteria: Dietzia spp (anaerobic  gram-positive coccus, order of actinomycete). Noninfectious causes of CRP have been suggested but seem less likely including endocrine disorders especially insulin resistance explained by the pro-mitotic and anti-apoptotic effects of hyperinsulinemia, reaction to UV light and a variant of cutaneous amyloidosis1,4. Our patient was not obese and did not have diabetes, the eruption was located on a covered area and histology did not show amyloid deposits upon Congo red coloration.
Oral minocycline 50-100mg twice daily is the first line treatment3. Recent reports of the efficiency of macrolides may make these antibiotics the privileged treatment for CRP, as they are safer than minocycline5. These medications are effective because they are antibacterial but most importantly anti-inflammatory3. Systemic retinoids were previously used because of their keratoregulatory effect but have now given way to safer treatments like minocycline and azithromycin5–7. Lately, Ozdemir et al reported the effectiveness of oral contraceptives that contain progesterone in the treatment of CRP in a patient with polycystic ovarian syndrome8. More recently, Krishnamoorthy et al described a case of CRP that started to resolve immediately after bariatric surgery9. These observations strengthen the hypothesis of the hormonal factor in the genesis of CRP.