DOI: 10.7241/ourd.20122.33                                                                 article in PDF
Our Dermatol Online. 2012; 3(2): 141-142
Date of submission: 20.03.2012 / acceptance: 21.03.2012
Conflicts of interest: None


Antonio Chuh1, Vijay Zawar2

1School of Public Health, The Chinese University of Hong Kong
2Godavari Foundation Medical College, India
Corresponding author: Prof. Antonio Chuh
                                 Prof. Vijay Zawar
How to cite an article: Chuh A, Zawar V. Case reports and studies on pityriasis rosea – from number of patients to meta-analyses and diagnostic criteria. Our Dermatol Online 2012; 3(2): 141-142.

Sir, We read with admiration the case report by Brzezinski and Sinjab on pityriasis rosea (PR) in a 12-month-old infant [1]. Despite more than a century of research, the underlying viral aetiologies, immunopathogenesis, diagnostic methods, specific diagnostic investigations, and optimal evidence-based management of PR are not yet within reach. There exist many case reports which, like the present report, are outstanding in supplementing individual clinical data to original studies on PR. However, original studies in PR [2-4] were typically performed on a relatively small number of patients, say below 100 patients. Owing to these small numbers, the powers of individual studies are low. Theoretically, these studies can be meta-analysed to achieve high statistical powers and high clinical significance. However, a Cochrane review [5] has pointed out that such meta-analyses cannot be validly performed as the diagnosis of PR is clinical and various investigators adopt different inclusion and exclusion criteria in their studies. The high heterogeneity between study populations limits not only meta-analyses but also systematic reviews. We have previously reported a study on 1379 patients with PR [6]. However, we admit that as our data was from three geographical locations with differing diagnostic criteria, the heterogeneity of these patients was high. Based on our previous experience on validating a diagnostic criteria for another paraviral exanthem, namely Gianotti-Crosti syndrome [7, 8], we have proposed a diagnostic criteria for typical and atypical PR [9, 10] (Tab. I). Despite this case report [1] not being a formal research study, we believe that the application of a diagnostic criteria is useful. If it is stated in many future case reports that the exanthems of the patients (be they being infants, children or an adults) fulfil or do not fulfil the diagnostic criteria, the data of case reports adopting the same diagnostic criteria will be of low heterogeneity, and therefore can be meta-analysed and systematically reviewed with regard to aetiology, immunopathogenesis, and management strategies. For this infant in concern [1], we believe that the rash fulfils all the three essential clinical features (discrete annular lesions, scaling, peripheral collarette scaling with central clearance on at least two lesions), all three optional clinical features (relative truncal distribution, orientation along skin cleavage lines, herald patch), and none of the exclusional clinical features. This case thus fulfils the set of diagnostic criteria as a whole [9, 10]. We advocate future authors PR to try and apply this criteria for case reports and original studies on PR. We are working on validation studies for the diagnostic criteria of PR. We would welcome comments, suggestions and expressions of interest in validation studies by prospective authors working on this disease.
A patient is diagnosed as having pityriasis rosea if:
1. On at least one occasion or clinical encounter, he / she has all the essential clinical features and at least one of the optional clinical features, and
2. On all occasions or clinical encounters related to the rash, he / she does not have any of the
exclusional clinical features.
The essential clinical features are:
1. Discrete circular or oval lesions,
2. Scaling on most lesions, and
3. Peripheral collarette scaling with central clearance on at least two lesions.
The optional clinical features are:
1. Truncal and proximal limb distribution, with less than 10% of lesions distal to mid-upper-arm and
2. Orientation of most lesions along skin cleavage lines, and
3. A herald patch (not necessarily the largest) appearing at least two days before eruption of other lesions, from history of the patient or from clinical observation.
The exclusional clinical features are:
1. Multiple small vesicles at the centre of two or more lesions,
2. Two or more lesions on palmar or plantar skin surfaces, and
3. Clinical or serological evidence of secondary syphilis.
Table I. Proposed diagnostic criteria for pityriasis rosea [9, 10]
1. Brzezinski P, Sinjab AT: Pityriasis Rosea in 12-months-old infant. Our Dermatol Online 2012; 3: 119-122.
2. Lallas A, Kyrgidis A, Tzellos TG, Apalla Z, Karakyriou E, Karatolias A, et al: Accuracy of dermoscopic criteria for the diagnosis of psoriasis, dermatitis, lichen planus and pityriasis rosea. Br J Dermatol 2012; doi: 10.1111/j.1365- 2133.2012.10868.x. [Epub ahead of print]
3. Ehsani A, Esmaily N, Noormohammadpour P, Toosi S, Hosseinpour A, Hosseini M, et al: The comparison between the efficacy of high dose acyclovir and erythromycin on the period and signs of pitiriasis rosea. Indian J Dermatol 2010; 55: 246- 248.
4. Lim SH, Kim SM, Oh BH, Ko JH, Lee YW, Choe YB, et al: Low-dose Ultraviolet A1 Phototherapy for Treating Pityriasis Rosea. Ann Dermatol 2009; 21: 230-236.
5. Chuh A, Dofitas B, Comisel G, Reveiz L, Sharma V, Chu V: Interventions for pityriasis rosea. Cochrane Database Syst Rev 2007; 2: CD005068.
6. Chuh A, Molinari N, Sciallis G, Harman M, Akdeniz S, Nanda A: Temporal case clustering in pityriasis rosea – a regression analysis on 1379 patients in Minnesota, Kuwait and Diyarbakýr, Turkey. Arch Dermatol 2005; 141: 767-771.
7. Chuh AAT: Diagnostic criteria for Gianotti-Crosti syndrome – a prospective case control study for validity assessment. Cutis 2001; 68: 207-213.
8. Chuh A, Lee A, Zawar V: The diagnostic criteria of Gianotti- Crosti syndrome – are they applicable to children in India? Pediatr Dermatol 2004; 21: 542-547.
9. Chuh AAT: Diagnostic criteria for pityriasis rosea – a prospective case control study for assessment of validity. J Eur Acad Dermatol Venereol 2003; 17: 101-103.
10. Chuh AAT, Zawar V: Pityriasis rosea. In: Harper’s Textbook of Pediatric Dermatology (third edition). Edited by Irvine AD, Hoeger PH, and Yan AC. Wiley-Blackwell, Oxford, a John Wiley & Sons Ltd Publication, 2011 (ISBN: 978-1-4051-7695- 8). Chapter 84: 84.1-84.5.

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