Dermatologica Sinica

: 2019  |  Volume : 37  |  Issue : 2  |  Page : 106--107

Pityriasis rubra pilaris with acantholysis mimicking pemphigus foliaceus: A diagnostic pitfall

Teng-Li Lin1, Chao-Kuei Juan2, Yi-Ju Chen2, Chi-Shun Yang3, Chien-Shan Chiu1,  
1 Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan
2 Department of Dermatology, Taichung Veterans General Hospital, Taichung; Department of Dermatology, National Yang-Ming University, Taipei, Taiwan
3 Department of Pathology, Taichung Veterans General Hospital, Taichung, Taiwan

Correspondence Address:
Dr. Chien-Shan Chiu
Department of Dermatology, Taichung Veterans General Hospital, No. 1650, Section 4, Taiwan Boulevard, Taichung 40705

How to cite this article:
Lin TL, Juan CK, Chen YJ, Yang CS, Chiu CS. Pityriasis rubra pilaris with acantholysis mimicking pemphigus foliaceus: A diagnostic pitfall.Dermatol Sin 2019;37:106-107

How to cite this URL:
Lin TL, Juan CK, Chen YJ, Yang CS, Chiu CS. Pityriasis rubra pilaris with acantholysis mimicking pemphigus foliaceus: A diagnostic pitfall. Dermatol Sin [serial online] 2019 [cited 2022 Aug 9 ];37:106-107
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Full Text

Dear Editors,

Pityriasis rubra pilaris (PRP) is a rare papulosquamous disorder of unknown etiology. It is clinically characterized by scaly reddish-orange papuloplaques and palmoplantar keratoderma. The typical histological features include follicular plugging, alternating orthokeratosis and parakeratosis, and psoriasiform hyperplasia.[1] Acantholysis is an occasional histological feature that has received recent emphasis and easily misleads clinicians.[2],[3],[4] Herein, we report a rare case of acantholytic PRP that mimicked pemphigus foliaceus (PF).

A 40-year-old male presented with a 1-month history of asymptomatic eruptions on his face and trunk. He denied any personal or family history of skin disease. On examination, multiple erythematous papules and plaques with overlying shallow erosions and collarettes of scales on his forehead, cheeks, and chest were discovered [Figure 1]a, [Figure 1]b, [Figure 1]c. The clinical impression included psoriasis, subacute cutaneous lupus erythematosus, and PF. Histopathology of a biopsy sample revealed detached stratum corneum and foci of subcorneal acantholysis [Figure 1]d and [Figure 1]e. The result of direct immunofluorescence was negative, whereas the result of indirect immunofluorescence (IIF) testing for anti-intercellular substance (ICS) autoantibodies was positive with a titer of 1:80. PF was strongly considered, and prednisolone was administered. However, the eruptions appearing on his face, trunk, and lower extremities progressed over 1 month and presented as numerous erythematous papuloplaques with coalescence. Islands of normal skin were apparent; coarse scales developed as a result of lamellar exfoliation; and diffuse, waxy, erythematous to orange hyperkeratoderma of the palms and soles was also found [Figure 2]a, [Figure 2]b, [Figure 2]c. The clinical presentation suggested PRP. Retrospectively, the initial biopsy was reexamined, focusing on the detached stratum corneum where foci of a checkerboard pattern of alternating orthokeratosis and parakeratosis were found [Figure 2]d and [Figure 2]e. The diagnosis of PRP was established. Prednisolone was discontinued, and he was started on acitretin (50 mg daily). The cutaneous lesions gradually resolved over a 2-year period [Supplementary Figure 1]a and [Supplementary Figure 1]b[SUPPORTING:1]. The follow-up IIF testing was negative after skin recovery.{Figure 1}{Figure 2}

PRP with acantholysis was first described by Kao and Sulica in 1989.[2] Initially, the acantholysis was thought to be an incidental observation or a processing artifact, rather than a specific feature, and subsequent reports documented this finding in cases of PRP.[3],[4] In a more recent case series concerning PRP, Avitan-Hersh and Bergman[4] reported that acantholysis was present in 6.5%–46% of the step sections in 5 of 23 biopsies taken from 4 of 12 patients. None of these biopsies included the initial section, which suggested that acantholysis was a meaningful pathological feature but could only be observed in the minority of PRP biopsies. In the reported cases, the biopsy sites varied and included the face, trunk, and extremities. Lesions could be follicular or nonfollicular and with or without erosive surfaces. Both bland and dyskeratotic acantholysis were addressed, and all levels of the epidermis could be affected.[2],[3],[4] The nonspecific pattern of acantholysis in PRP indicated that the pathogenesis could resemble that of Grover's disease, in which acantholysis was speculated to be induced by proteolytic enzymes in occlusive acrosyringia.[3],[5]

Our patient initially presented with only scaly erythematous papuloplaques that clinically seemed to be PF. Despite the negative direct immunofluorescence result, the histologic features of the subcorneal cleft and acantholysis and the positive ICS IIF test result at the beginning nevertheless misled us to suspect PF. Not until the characteristic appearance of erythematous papuloplaques with islands of spared skin and palmoplantar keratoderma developed did we become aware that it may be a case of PRP with acantholysis rather than PF. The retrospective microscopic findings of alternating orthokeratosis and parakeratosis over the detached stratum corneum, the positive response to acitretin treatment, and IIF test results in which anti-ICS autoantibodies were not detected after skin recovery all supported the diagnosis of PRP. The transient anti-ICS autoantibody staining during the initial disease course was considered to be a false-positive result. We conjectured that, in the present case, PRP with acantholysis may have caused the exposure of epidermal antigens and subsequently induced the production of anti-ICS autoantibodies, as other studies have documented in patients with transient false-positive ICS IIF test results.[6],[7]

In conclusion, acantholysis could be detected in PRP histologically. Awareness of this uncommon feature may help avoid misdiagnosis of PRP as another type of acantholytic dermatoses.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.


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