Pityriasis Rosea Like Drug Rash – A Need to Identify the Disease in Childhood

Pityriasis rosea is a common dermatosis named by Gibert in 1860. It is an acute self limiting papulosquamous disease, probably infective in origin affecting healthy adolescents and young adults. It is characterized by distinctive skin eruptions and minimal constitutional symptoms. Drug induced pityriasis rosea tend to occur in older generation and resolution seen only after withdrawal of the offending drug. We report a case of 12-year-old boy with erythematous papules distributed over trunk and proximal arms after nimesulide therapy consistent with a clinical diagnosis of atypical pityriasis rosea. The relation of drug and development of pityriasis rosea is confirmed by dechallenge test of the suspected drug.

A 12-year-old boy was referred to the outpatient department of dermatology with complaints of itchy rash over body with fever since 10 days. Clinical examination revealed multiple, discrete skin coloured to erythematous papules distributed mainly over trunk and bilateral proximal arms with grouping on few areas. These papules were distributed along the lines of cleavage on the back [Table/Fig-1]. There was sparing of face, scalp, flexures, palms, soles, lower extremities and all mucous membranes. Other local and systemic examinations were within normal limits. Routine blood investigations revealed mild eosinophilia. There was no history of any preceding upper or lower respiratory tract infection, vaccination, unprotected sexual exposure or photosensitivity.

[Table/Fig-1]:

Discrete skin coloured to erythematous papules with grouping on few areas along the lines of cleavage

He was started on oral nimesulide for fever by the local physician, two days following which he developed the itchy rash, initially on the trunk and gradually extending to the upper extremities. He had also received oral chloroquine for fever, but it was started after development of the rash. Suspecting nimesulide to be the causative factor for the atypical rash, it was discontinued and he was started on paracetamol for fever and antihistamine. Seven days later his father reported complete resolution of the rash and fever.

Pityriasis rosea is a common, acute, self limiting exanthem of uncertain etiology affecting mainly children and young adults. The cause is not known but a host of infectious agents have been incriminated. Many studies have focussed on HHV-6 and HHV-7 as causative agents for pityriasis rosea [1–3]. A similar rash to this condition is attributed to several drugs and it recovers on withdrawal of the offending drug. The common drugs implicated include, ACE inhibitors, hydrochlorothiazide, captopril, barbiturates, gold, metronidazole, allopurinol, nimesulide, etc [4]. Frequency of drug induced pityriasis rosea is probably under reported. Clinically the idiopathic form is characterized by an initial herald patch (mother patch), followed by diffuse crops of pinkish papules and plaques with typical collaret of scales, appearing on trunk and proximal extremities along the Langhan’s lines of cleavage, giving the classical “Christmas tree pattern” appearance. The disease normally resolves spontaneously within 4-8 weeks, but in drug induced form the typical herald patch may be absent and the resolution of lesions occur only after withdrawal of the drug.

As skin is a common target for drug reactions and many skin disorders can be imitated, induced or aggravated by various drugs, the dermatologist’s role in identifying drug reactions is crucial. Pityriasis rosea is one such skin disorder which can be imitated by many drugs.

Diagnosing pityriasis rosea is nearly always through history and physical examination alone. Histopathological study is required only in atypical cases. The clinical manifestations of drug induced pityriasis rosea are very similar to that of the idiopathic one. The following differences from the idiopathic form of the disease were noted in a study [4]:

a) The absence of an evocative, single “herald” patch.

b) The marked inflammatory colour of the lesions, tending to bright violet-red.

c) The severity of itching, and lack of response to antihistamines.

d) The presence of increased eosinophils in the blood and in the skin infiltrate.

The clinical suspicion of a drug etiology is confirmed by the recovery of the lesions after withdrawal of the drug.

Atzori L et al., [4] in a study found 2% of the adverse cutaneous reactions presenting as features of idiopathic pityriasis rosea. Pityriasis rosea like drug rash was seen more commonly in old as compared to the idiopathic disease which is common in young population.

The common differential diagnosis of pityriasis rosea includes tinea corporis, secondary syphilis, guttate psoriasis, parapsoriasis, truncal pityriasis lichenoides, nummular dermatitis etc.

Although drug induced pityriasis rosea is common in old age group, our case was a paediatric patient. Since idiopathic pityriasis rosea is common in this age, a high degree of clinical awareness is needed to suspect a drug aetiology in this case.

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