Pityriasis Rosea


Source

Location

Population

No. of patients

Incidence

Male:female ratio

Age range

Peak age

Seasonal variation

Jacyk [6]

Nigeria

All

138

2.42/100 Dermatologic patients

1.0:1.12

18 months to 55 years

15–24 years

No variation

Messenger et al. [15]

England

All

126

Not reported

1.0:1.8

Not reported

Not reported

Higher incidence in winter months

Chuang et al. [7]

Rochester, MN

All

939

172.2/100,000 Person-years

1.0:1.76

10 months to 78 years

10–35 years

Significantly higher in colder months

Ahmed [16]

Sudan

All

81

1.09/100 Dermatologic patients

1.0:1.53

Not reported

6–30 years

Peaked in cold and dry season

Olumide [17]

Lagos

All

152

4.80/100 Dermatologic patients

1.0:1.20

91 % between 5 and 35 years

10–14 years

Peaked during early part of rainy season (March to July)

Cheong and Wong [8]

Singapore

All

214

Not reported

1.85:1.0

1–61 years

20–24 years

Higher incidence in March, April, and November

Harman et al. [4]

Eastern Anatolia

All

399

0.75/100 Dermatologic patients

1.0:1.21

87 % between 10 and 39 years

20–29 years

Peaked during spring, autumn, and winter

Nanda et al. [18]

Kuwait

Children aged 12 and below

117

1.17/100 Aged 12 and below

1.0:1.38

Not reported

Not reported

Not reported

Tay and Goh [5]

Singapore

All

368

0.65/100 Dermatologic patients

1.19:1

9 months to 82 years

20–29 years

No variation

Chuh et al. [9]

Hong Kong

All

41

Not reported

1.0:1.05

5–54 years

Mean age 25.9 years

Slightly higher incidence in colder months and months with less rainfall

But noted to be insignificant

Kyriakis et al. [10]

Athens

All

479

0.95/100 Dermatologic patients

1.0:1.4

35 days to 96 years

First peak male 6–10 years

Second peak male 36–40 years

First peak female 21–25 years

Second peak female 31–35 years

Not reported

Sharma and Srivastava [11]

India

All

200

0.25/100 Dermatologic patients

2.0:1.0

1.5–65 years

13–36 years

Higher incidence from September to December

Gunduz et al. [19]

Turkey

Pediatric

51

Not documented

1.1:1.0

Not reported

6–11 years

Mean age 8 years

Peaked in winter

Ayanlowo et al. [12]

Lagos

All

427

3.7/100 Dermatologic patients

1.0:1.55

Not reported

10–29 years

Peaked in rainy season





Pathophysiology


As the condition is typically a self-limiting disorder, with seasonal clustering, predominance during cold or winter months [7, 9, 11, 1517, 19], and few recurrences, it is thought to be due to an infection, usually precipitated by an upper respiratory tract infection, with long-lasting immunity [4, 8, 15]. Many infective agents have been implicated, e.g., Influenza A, H1N1 [20, 21], cytomegalovirus [22], Epstein–Barr virus [23], parvovirus B19 [24] and Mycoplasma pneumoniae [25]. However, prospective studies have failed to show a significant change in serological titers in acute and convalescent stages for mycoplasma, cytomegalovirus, Epstein–Barr virus and parvovirus B19 [26, 27]. There are reports of the association of human herpesvirus-7 (HHV-7) with polymerase chain reaction (PCR) analysis and less so human herpesvirus-6 (HHV-6) with pityriasis rosea [2831]. But they remain controversial [3234].


Clinical Presentation






  • A herald patch may be present


  • Distribution of rash is typically over Langer’s cleavage lines over the trunk


  • Atypical presentations over the scalp, face, limbs, palms, and soles can be found

A herald patch, which is a single isolated lesion, can be found classically on the trunk but can also occur on the upper arm, neck, or thighs. The herald patch is seen in 17–94 % of cases [5, 26]. This oval patch varying from about 1 to 10 cm with collarette scaling can be mistaken for tinea corporis or eczema. Approximately 5 % of patients may feel a mild prodrome of headache, fever, malaise, or arthralgias [35]. Within a few days after the herald patch, there is a subsequent secondary eruption over the trunk and proximal extremities of lesions in a T-shirt and shorts distribution with peripheral collarette scaling (Figs. 33.1 and 33.2) which has been reported to be enhanced by epiluminescence dermatoscopy [36].

A310620_1_En_33_Fig1_HTML.jpg


Fig. 33.1
Papules and plaques over the trunk with peripheral collerette scaling in a ‘fir tree’ pattern


A310620_1_En_33_Fig2_HTML.jpg


Fig. 33.2
Papules and plaques over the trunk with peripheral collerette scaling

The orientation of these lesions on the posterior trunk is referred to as a “fir tree” or “Christmas tree” pattern [37]. “Langer’s cleavage lines” is now proposed to be the most appropriate term with the V-shaped pattern on the upper chest and back, circumferential pattern around the shoulders and hips, and transverse pattern on the lower anterior trunk and lower back (Fig. 33.3) [38]. Atypical forms of pityriasis rosea include an inverse pattern where the face and extremities are affected more than the trunk [39]. African patients have been reported to have a more extensive rash with more frequent involvement of the face and scalp [6]. It has been reported to present in the scalp in children [40] and when presenting on the soles can mimic secondary syphilis [41]. Other atypical forms of presentation include a vesicular eruption [42], erythema multiforme-like rash [43], urticarial [44], and purpuric variants [44, 45].

A310620_1_En_33_Fig3_HTML.jpg


Fig. 33.3
Papules and plaques in a circumferential pattern along Langer’s cleavage lines


Treatment






  • Symptomatic treatment includes antihistamines and topical corticosteroids


  • Phototherapy or natural sunlight exposure may help ease pruritus and hasten resolution of rash in some patients, but there is an increased risk of post-inflammatory hyperpigmentation especially in darker skin types


  • Erythromycin or acyclovir can be tried to hasten resolution of the rash and decrease pruritus

As the condition is self-limiting in about 6–8 weeks, treatment may not be necessary (Table 33.2). However, pruritus can be bothersome and oral antihistamines and topical corticosteroids may be helpful. These provide symptomatic relief but do not help in the clearance of the rash [46]. Systemic steroids have not been shown to be effective [46, 47]. Exposure to UV-B therapy starting at 80 % of the minimum erythrogenic dose may relieve pruritus in as little as 24 h but may increase the incidence of post-inflammatory hyperpigmentation [4850]. Alternatively, low-dose (10–30 J/cm2) UV-A1 phototherapy given 2–3 times a week until resolution may be tried [51]. Early administration of erythromycin 1 g taken orally in four divided doses for adults or 25–40 mg/kg divided four times daily in children for 2 weeks in a double-blind placebo controlled trial led to early resolution of symptoms [52]. However, subsequent studies did not find erythromycin or azithromycin useful [53, 54]. There is some evidence that oral acyclovir 1 g five times a day for 7 days at the onset in adults has been shown to shorten the duration of the disease [55, 56]. Subsequently, lower dosages of acyclovir 400 mg five times a day for 1 week was shown to be equally effective [57]. Recent studies have shown that despite its effectiveness in herpes simplex virus infection, acyclovir was not as effective as ganciclovir and forcarnet against HHV-6 and 7 [58]. This is because acyclovir is thymidine kinase-dependent whereas HHV-7 lacks the thymidine kinase gene [59]. There are yet to be published data on the effectiveness of ganciclovir and forscarnet in pityriasis rosea.
Nov 2, 2016 | Posted by in PEDIATRICS | Comments Off on Pityriasis Rosea
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