Pityriasis rosea ( PR ) is an acute , benign , self limiting papulosquamous exanthem of an unknown etiology
First described by Gilbert in 1860 Pityriasis means rose colured scale Also known as pityriasis circinata , roseola annulata and herpes tonsurans maculosus Happens worldwide with no genetic or racial predisposition Most common in people aged 10-35 yrs Seen rarely in children < 10 Slight female preponderance Community based incidence is reported to be 172.2 per 100 ,000 persons year Prevalence for young people aged between 10-29 yrs is reported to be 0.6 % other studies quote that the approximate incidence of PR is 0.5 % to 2 % Seen in all seasons but some studies suggest an increase in spring and fall.
Cause -The cause is not clear and is widely debated Various agents . causes have been postulated for e.g - infective agents as viruses , bacteria , spirochetes - non infective etiologies as atopy and autoimmunity - Infectious cause is widely implicated and it is said that the following points support an infectious cause - outbreak in clusters ie infectious agent is circulating in the community - recurrence of infection outside the acute phase is rare ie long lasting immunity - many patients report a prodromal illness before the herald patch appears - some patients show an increase in B lymphocytes , a decrease in T lymphocytes and elevated ESR Both bacteria and viruses have been blamed for e.g - URTI preceding PR suggests a role of Streptococcus - light and electron microscopy findings suggest infection with human herpesvirus 6 and 7 ( HHV 6/7 ) Drugs have been implicated. BMJ paper report that - no herald patch is seen in drug induced cases - individual lesions tend to be violet red in colour - pruritus is more severe - eosinophilia may be present Common medications implicated include metronidazole terbinafine ACE inhibitors ( captopril ) clonidine atenolo barbiturates allopurinol isotretinoin hydrochlorothiazide nortriptyline clozapine biologics omeprazole lamotrigine
Presentation -begins with a ( most cases ) erythematous plaque called the herald patch or mother patch asymptomatic thin oval scaly patch often seen on the trunk followed by the neck or proximal extremity usually well demarcated 2-4 cm in dia & slightly raised can be salmon coloured or hyperpigmented collarette scaling is common. the eruption may be preceded by a prodrome of sore throat , lymphadenopathy , GI disturbance , fever and arthralgia as symptoms are minor the patient may not report them about 40% to 90 % of cases will begin with a herald patch more than one herald patch may be seen.
Secondary eruption -more generalised eruption follows the herald patch usually between 2-14 days but the range between the primary and secondary eruptions can vary from 2-84 days numerous smaller lesions -follow Langers line - configuration of a Christmas tree , inverted Christmas tree , fur tree- when the lesions appear on the back - when they appear elsewhere on the body they follow the cleavage lines b/l diffuse and symmetrical with the long axis running parallel to skin tension lines lesions may appear in crops and occur as macules and papules and are pink-red ( salmon coloured ) or fawn coloured circular or oval , raised and have the same collarette of scale as the herald patch they most commonly involve the thorax , back , abdomen and adjoining areas of the neck and extremities lesions are not vesicular and do not tend to occur on palmar or plantar skin surfaces.
African patients have been reported to suffer with a more extensive rash which involves frequently the face and scalp the rash is not erythematous post-inflammatory hypopigmentation can be a matter of cosmetic concern and is seen more frequently
the rash typically lasts for 5 weeks and resolves by 8 weeks in more than 80 % of cases.
What else can it be ? Not all patients will present with typical morphology and distribution and you should consider the fact that about 20 % of the patients may present with atypical PR in which the morphology , distribution , size , number severity and the disease course is unusual
Atypical PR -Rash morphology may be atypical as vesicular m purpuric or haemorrhagic and urticarial PR gigantea of Darier is PR with enormous plaques PR inversus involves the face , axillae and groins with relative sparing of the trunk BMJ reports that more common atypical variants include unilateral , purpuric , erythema multiforme – like and urticaria type.
Differentials -if palms and soles are affected and the patient is sexually active – consider the possibility of secondary syphilis Dermatophytosis Guttate psoriasis ( often confused with PR ) - multiple small , round or oval 2mm to 1 cm pink or red scaly papules - trunk and proximal limbs Nummular ( discoid ) eczema - very itchy - coin shaped plaques which may be vesicular or crusted - on limbs and lesser extent on trunk Pityriasis lichenoid chronic Cutaneous T-cell lymphoma Erythema chronic migrans Tinea corporis Viral exanthem Subacute cutaneous lupus erythematosus.
Drug induced -absence of single herald patch lesions are marked inflammatory -tend to be bright violet red severe itching which may not respond to antihistamines if testing is available -eosinophilia ( blood & skin infiltrate )
Diagnosis -Diagnosis is established with thorough history and physical examination. It may not always be easy to diagnose PR as at the onset of symptoms diagnosis may not be clear no tests available which can confirm the condition in primary care presentation can be non -specific wide differential diagnosis several diagnostic criteria have been proposed for typical and atypical PR but their reliability and applicability in all ethnic groups is uncertain ( BMJ )
Further testing-Dermatoscopy may help differentiate PR from other conditions Skin biopsy may help if diagnostic uncertainty persists Atypical presentation – histopathology may be helpful Blood tests may help if autoimmune conditions as SLE is being considered in the differentials
Treatment -self limiting condition -reassurance and symptomatic Rx will suffice in most cases you may offer patients - emollients - antihistamines - topical steroids ( mildly/ moderately potent steroid cream/oint up to 4 weeks ) - severe itch not responsive to above consider oral steroids Phototherapy ( use is controversial ) Macrolides – use is experimental Acyclovir – not yet advocated for use Drug induced – consider stopping the drug
Pregnancy -refer/ discuss urgently with secondary care as some reports mention that PR may be associated with premature birth.
Morbidity -Pigmentation changes in dark skinned individuals can be distressing – scarring does not happen
Daniel L et al in AFP article suggest that persistence of rash / pruritus beyond 3 months is highly unlikely in PR- review the diagnosis/cause and seek help.
PATIENT INFORMATION LINKS
British Association of Dermatologists on PR 3 page leaflet https://www.bad.org.uk/shared/get-file.ashx?id=225&itemtype=document
Dermnetz with photos https://dermnetnz.org/topics/pityriasis-rosea/
National Organization of Rare Diseases on PR https://rarediseases.org/rare-diseases/pityriasis-rosea/
Lot of images compiled by the Primary Care Dermatology Society page on PR ( for HCP’s ) http://www.pcds.org.uk/clinical-guidance/pityriasis-rosea
- Urbina, Francisco et al. “Clinical variants of pityriasis rosea.” World journal of clinical cases vol. 5,6 (2017): 203-211. doi:10.12998/wjcc.v5.i6.203
- Litchman G, Nair PA, Le JK. Pityriasis Rosea. [Updated 2020 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448091/
- Pityriasis rosea: An update on etiopathogenesis and management of difficult aspects
Mahajan Khushbu, Relhan Vineet, Relhan Aditi Kochhar, Garg Vijay Kumar
Year : 2016 | Volume: 61 | Issue Number: 4 | Page: 375-384
- Panda,M.Patro,N.Jena,M.Dash,M.Mishra,S.(2014).Pityriasis Rosea Like Drug Rash – A Need to Identify the Disease in Childhood, 8(8), YD01-YD02.
- Pityriasis rosea
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- Pityriasis rosea – An update
Chuh Antonio, Lee Albert, Zawar Vijay, Sciallis Gabriel, Kempf Werner
Year : 2005 | Volume: 71 | Issue Number: 5 | Page: 311-315
- Pityriasis Rosea CKS NHS Pityriasis rosea | Topics A to Z | CKS | NICE
- Chuh, A., Zawar, V., Sciallis, G. and Kempf, W. (2016), A position statement on the management of patients with pityriasis rosea. J Eur Acad Dermatol Venereol, 30: 1670-1681. https://doi.org/10.1111/jdv.13826
- BMJ Best Practice Pityriasis rosea ( summary ) Pityriasis rosea – Symptoms, diagnosis and treatment | BMJ Best Practice
- Mayfield J, Solomon M, Plamoottil C I, et al. (August 19, 2020) Childhood Pityriasis Rosea With Multiple Herald Patches. Cureus 12(8): e9876. doi:10.7759/cureus.9876