Annular groin eruptions: pityriasis rosea of vidal

A male school teacher, aged 34 years, was referred for moderately pruritic, progressive annular eruptions in the groin, which had lasted two weeks, and were unresponsive to systemic iatroconazole. The eruptions consisted of multiple, large and small oval and round erythematous plaques, bilaterally in the inguino-crural folds (Fig. 1), and coalescent in places (Fig. 2), involving part of the thighs and buttocks (Fig. 3), all having a peripheral rim of collarette scales and central clearing (Fig. 4). There were a few small discrete scaly plaques on the dorsal penis and scrotum and even on the forearms (Fig. 1). Three weeks previously, the patient had had a history of mild malaise, fever, and sore throat, which had lasted for three days, and which was relieved without any medication. Apart from one enlarged inguinal node and mild throat congestion, the rest of the clinical examination was normal. Sudden onset of multiple annular scaly plaques on inguino-crural folds involving part of the thighs, scrotum, and penis Close-up view of the right groin, showing large-sized oval and circinate coalescent plaques with central clearing, and pigmentation with collarette scales and perilesional erythema. Also seen in the surrounding area are the plaques with intense erythema as evolving lesions. Crusting was noted medially Involvement of medial aspects of the buttocks and posterior thighs Close-up of a typical collarette scale, one of the diagnostic features of pityriasis rosea His investigations included KOH microscopy for fungus, complete blood counts, blood sugar levels, Venereal Disease Research Laboratory test, human immunodeficiency virus antibodies, Anti-Streptolysin O titer, which were all normal or negative. Skin biopsy revealed features of acute spongiotic dermatitis, with inflammatory cells in the upper dermis. Complete resolution followed a treatment with roxithromycin, hydroxyzine hydrochloride orally, and mometasone ointment topically, leaving a slight hyperpigmentation. No recurrence was noted. After its first description by Jean Baptiste Emile Vidal in 1882,1,2 which he named pityriasis circiné et marginé, there are not too many published reports on pityriasis rosea of vidal (PRV). The photographs illustrate PRV, which is a rare variant of pityriasis rosea (PR), characterized by the appearance of secondary eruptions in the axillae and/or groin.3,4 Hence, it is also called “limb girdle pityriasis rosea.” PRV has distinct morphological features of multiple, large, oval, or round, coalescent annular eruptions,1,4,5 which appear within a short span of a few days. The individual lesions range from 3–6 cm in diameter and characteristically have central clearing and a rim of collarette scales with surrounding erythema. Respiratory or gastrointestinal prodrome often precedes. Herald plaque may or may not be noted. The number of eruptions may be quite limited.2 The trunk and extremities are usually spared in PRV, which is the feature that differentiates this variant from the classical PR. However, a few small isolated eruptions elsewhere on the body may be seen in certain patients, in our experience. The involvement of penile and scrotal skin is rarely reported in PR, which in our experience is common in PRV. Adults are more frequently affected than children, and it may run a relatively prolonged course, taking as long as 2–5 months for complete healing. After healing there may be some pigmentation, especially in darker-skinned individuals.1,2,4,5 PRV is frequently misdiagnosed as dermatophytosis or annular syphilide at the first instance. Other conditions that it may mimic clinically are flexural psoriasis, drug eruption, contact dermatitis, erythema annulare centrifugum, and parapsoriasis. It may also be confused with PR, having multiple herald plaques, which occurs in about 5% of individuals.3 Therefore, a careful history, appropriate investigations, and good follow-up are a must to reach a diagnosis. The purpose of this article is to make clinicians aware of this distinct variant of PR, which might be misdiagnosed and under-reported.