Scaly Papules on the Trunk and Vesicles on the Palms and Soles in Two Young Adults.

Learning Points

Pityriasis rosea (PR) is a common papulosquamous eruption that classically consists of an initial salmon pink patch followed by a scaly pink papular eruption on the trunk and extremities aligned along the natural lines of cleavage.

Atypical morphologic variants of PR, including vesicular, inverse, urticarial, and purpuric subtypes, can occur in up to 20% of all cases and complicate clinical diagnosis.

In vesicular PR the vesicular eruption is generally localized to the palms and soles and occurs in conjunction with classic papulosquamous lesions on the trunk.

Morphologically the differential diagnosis of vesicular PR includes varicella, dyshidrotic eczema, and palmoplantar pustulosis.

Consider skin biopsy and diagnostic studies in cases of vesicular PR and other atypical morphological variants to rule out papulosquamous dermatoses with similar morphological features, including syphilis and dermatophytosis.

History, Examination, and Investigative Findings

A 28-year-old Asian female and 33-year-old Asian male independently presented in the same week for evaluation of a diffuse, erythematous, scaly, and mildly pruritic eruption. Two weeks prior, both recalled a focal rash on the trunk that progressively spread throughout the trunk, palms, and soles. Both were healthy without systemic symptoms or recent illness. Physical examination revealed tense vesicles overlying pink patches on the palms [Figure 1] and soles accompanied by oval, pink papules and plaques with a collarette of scale on the back [Figure 2], flanks, abdomen, and inner thighs. A punch biopsy from the trunk of each patient showed similar changes: epidermal spongiosis and mild acanthosis with mounds of parakeratosis alternating with orthokeratosis [Figure 3], and mild dermal edema with variable mononuclear cell infiltrate. Fungal and treponemal stains were negative. KOH scraping and rapid plasma reagin tests were also negative.

Figure 1

Tense vesicles overlying pink patches on the palm

Figure 2

Pink papules and plaques with collarettes of scale on the back

Figure 3

Cutaneous punch biopsy showing acanthosis, spongiosis, and mounds of parakeratosis alternating with orthokeratosis (H and E, original magnification ×40)

What's the Diagnosis?

Pityriasis Rosea (vesicular subtype)

Discussion

Both patients were treated with high potency topical corticosteroids. The eruption resolved completely in both cases.

Pityriasis rosea (PR) is a common papulosquamous dermatosis named for its characteristic skin lesions exhibiting a fine flaky scale (pityriasis) and pink-red hue (rosea). With an incidence estimated to be between 0.5 and 2%, it most often affects adolescents and young adults but can frequently present in young children and the elderly.[1]

While various exanthema resembling PR were first described in the eighteenth century by a variety of other names, including roseola annulate and erythema annulatum, PR was first officially characterized in 1860 by the French dermatologist Camille Melchoir Gibert.

PR most commonly (though not always) initially presents as a several centimeter, well-defined, round, and salmon pink patch (”herald patch”) on the neck or trunk. While initially without secondary change, the lesion quickly becomes scaly with central clearing (”collarette of scale”). Within days to weeks, morphologically similar but smaller lesions appear on the trunk and proximal extremities aligned parallel to the natural lines of cleavage (”Christmas tree distribution”). The exanthem is self-limited and typically resolves within two months without major sequelae. While PR is a clinical diagnosis, skin biopsy and additional diagnostic studies can aid greatly to rule out other papulosquamous dermatoses with similar morphological features, including secondary syphilis, which is preceded by a chancre and accompanied by positive treponemal serology, and tinea corporis, which has no preceding lesion but stains positive with KOH preparation.

Treatment is mainly symptomatic with topical corticosteroids showing good efficacy for pruritus. For severe eruptions acyclovir may shorten the duration and reduce the severity of the exanthem. Other reported treatments include erythromycin, phototherapy with narrow band UVB, and systemic corticosteroids. While controversial, studies have suggested a viral etiology for PR based on clustering of cases with seasonal variation, a viral prodrome that can precede the onset of rash, the presence of HHV-6 and HHV-7 viral DNA in individuals with PR, and an efficacious effect of acyclovir.

Atypical morphologic variants of PR occur in up to 20% of cases, further complicating clinical diagnosis.[2] Aside from classic macular PR, atypical variants include inverse, papular, urticarial, purpuric, and vesicular, an uncommon subtype seen here in our two patients. There are few reports of vesicular PR in the literature.[345] The vesicular eruption tends to be localized to the palms, soles, and forearms and can occur as individual lesions or clustered rosettes, usually in conjunction with classic papulosquamous lesions. Morphologically, the differential diagnosis includes: varicella (”dew drops on a rose petal”), which usually occurs in children or the immunosuppressed and is accompanied by systemic symptoms; dyshidrotic eczema (”tapioca pudding”), which is limited to the palms or soles and is accompanied by significant pruritus; and palmoplantar pustulosis, a variant of pustular psoriasis characterized by acral, neutrophil-rich pustules. Though both of our patients were young adults of Asian descent, there are no epidemiologic factors clearly associated with vesicular PR. Despite an overall prolonged disease course compared to typical PR, vesicular PR is self-limited without any long-term complications.

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Conflicts of interest

There are no conflicts of interest.