Case clustering in pityriasis rosea: a multicenter epidemiologic study in primary care settings in Hong Kong

OBJECTIVES: To investigate the epidemiology of pityriasis rosea in primary care settings in Hong Kong and to analyze for temporal clustering. DESIGN: Retrospective epidemiologic study. SETTING: Six primary care teaching practices affiliated with a university.Patients Forty-one patients with pityriasis rosea, 564 patients with atopic dermatitis (negative control condition), and 35 patients with scabies (positive control condition). METHODS: We retrieved all records of patients with pityriasis rosea, atopic dermatitis, or scabies diagnosed in 3 years. We analyzed temporal clustering by a method based on a regression model. RESULTS: The monthly incidence of pityriasis rosea is negatively but insignificantly correlated with mean air temperature (gamma s = -0.41, P =.19) and mean total rainfall (gamma s = -0.34, P =.27). Three statistically significant clusters with 7, 6, and 7 cases were identified (P =.03), occurring in the second coldest month in the year (February), the second hottest month (July), and a temperate month (April), respectively. For atopic dermatitis (negative control condition), the nonclustering regression model was selected by Akaike information criteria. For scabies (positive control condition), 1 cluster of 20 cases was detected (P =.03). CONCLUSIONS: Significant temporal clustering independent of seasonal variation occurred in our series of patients with pityriasis rosea. This may be indicative of an infectious cause.     

Is human herpesvirus 7 the causative agent of pityriasis rosea? – a critical review

BACKGROUND: Conflicting results on the association of pityriasis rosea and human herpesvirus 7 infection have been reported by different investigators. AIM: To review the level of evidence for such an association. METHODS: Medline was searched with unlimited data entry and 13 reports were retrieved. The data were analyzed for a causative association according to the criteria of Fredericks and Relman, which take into consideration latent infection and the reactivation of viruses characteristic of herpesviruses, and the roles of sequence-based detection methods. RESULTS: None of the criteria was substantiated by the findings of most investigators. Factors leading to the discrepancies of the results were discussed. CONCLUSION: There is currently insufficient evidence that human herpesvirus 7 infection is causally related to pityriasis rosea.     

The Diagnostic Criteria of Gianotti‐Crosti Syndrome: Are They Applicable to Children in India?

In order to evaluate the applicability of the diagnostic criteria to children with Gianotti-Crosti syndrome (GCS) in India we retrieved all clinical records of children with a definite diagnosis of this syndrome seen over 30 months in a private dermatology practice. The controls were children for whom Gianotti-Crosti had been suspected but the final diagnosis was not this syndrome, and children in whom it was not suspected but who were diagnosed with any of the differential diagnoses of the syndrome. We documented the presence or absence of the positive and negative clinical features for all patients and controls. The clinical records of 23 children with GCS and 74 controls were retrieved. The three positive clinical features--1) papules or papulovesicles 1-10 mm in diameter on at least three of the following four sites: cheeks, buttocks, extensor surfaces of the forearms, extensor surfaces of legs; 2) being symmetrical; 3) lasting for at least 10 days--were sensitive and positively correlated with GCS. Both negative clinical features--extensive truncal lesions and scaly lesions--are negatively correlated with this syndrome. All 23 children with GCS and none of the controls fulfilled the set of diagnostic criteria. We concluded that the Gianotti-Crosti diagnostic criteria are applicable to affected children in India.     

Pityriasis rosea: roles of the dermatology nurse

Pityriasis rosea, a self-limited exanthematous disease of unknown etiology, is a fairly common exanthem encountered by dermatology nurses and nurse practitioners. Their special roles in diagnosis, symptomatic relief, care for patients with atypical rash, patient education, and counseling are described.     

Effect on quality of life in patients with pityriasis rosea: Is it associated with rash severity?

BACKGROUND: It is unknown how the quality of life (QOL) is affected in patients with pityriasis rosea (PR), and whether it is related to rash severity. METHODS: We constructed a valid and reliable Cantonese version of the Dermatology Life Quality Index (DLQI). We recruited patients with PR, with atopic dermatitis and with acne vulgaris, and controls of the same sex and comparable age. We applied the DLQI and the Pityriasis Rosea Severity Score (PRSS) to the patients with PR, the DLQI and the SCORing Atopic Dermatitis Index (SCORAD) to the controls with atopic dermatitis, and the DLQI and the Leeds Acne Grading System (LAGS) to the controls with acne vulgaris. RESULTS: Total DLQI scores of the 22 patients with PR (mean: 6.36, SD: 5.79) were significantly lower than those of the 22 controls with atopic dermatitis (mean: 12.00, SD: 5.38) (P = 0.021), but were insignificantly different from those of the 22 controls with acne vulgaris (mean: 6.86, SD: 4.53) (P = 0.57). Correlation between the total DLQI and PRSS scores was weak (gamma(s) = +0.19) and insignificant (P = 0.40). All six DLQI parameters were insignificantly correlated with the PRSS scores. In contrast, the total DLQI scores and most of the DLQI parameters were strongly correlated with the rash severity scores for the control subjects. Significantly more patients with PR have concerns regarding disease etiology and infectivity. CONCLUSIONS: The QOL of the patients with PR was significantly less affected than that for the patients with atopic dermatitis, but was insignificantly different from the patients with acne vulgaris. Unlike atopic dermatitis and acne vulgaris, the effects on the QOL in PR are insignificantly correlated with rash severity. These results bear important implications on clinical management.     

Pityriasis rosea--an update

Recent controversies on the etiology, diagnosis and treatment have led to increased interest in pityriasis rosea (PR). We review these aspects of the disease. PR is universal. The incidence is around 0.68 per 100 dermatological patients, or 172.2 per 100,000 person-years. The prevalence in people aged between 10 and 29 years is 0.6%. The male to female ratio is around 1:1.43. Evidence on seasonal variation is conflicting, but there is no evidence that the incidence is dependent on mean air temperature, mean total rainfall, or mean relative humidity. Spatial-temporal and temporal clustering of cases of PR has been reported. The association of PR with human herpesvirus-7 infection is still controversial. Owing to the extreme high sensitivities of sequence-based detection methods such as polymerase chain reaction, novel criteria should be applied to evaluate the evidence. There is no evidence that PR is associated with other viral or bacterial infections. The role of autoimmunity in PR warrants further investigations. Many patients with PR have one or more atypical features. Application of validated diagnostic criteria may be helpful for atypical cases. The efficacy of macrolides, including erythromycin, in PR is still under evaluation. There is no evidence that antiviral agents are effective. The efficacies of ultraviolet radiotherapy and systemic corticosteroids are not well established. In managing a patient with PR, we should concentrate more on how the eruption is affecting the quality of life, i.e. the illness, rather than the extent and severity of the eruption, i.e. the disease.