Acantholytic pityriasis rubra pilaris associated with topical use of imiquimod 5%: case report and literature review

Abstract

Topical use of immune response modifiers, such as imiquimod, has increased in dermatology. Although its topical use is well tolerated, it may be associated with exacerbations of generalized cutaneous inflammatory diseases, possibly through the systemic circulation of pro-inflammatory cytokines. This report describes a case of development of pityriasis rubra pilaris, a rare erythematous-papulosquamous dermatosis, in a woman aged 60 years during treatment with imiquimod 5% cream for actinic keratosis. It evolved with erythrodermic conditions and palmoplantar keratoderma, presenting progressive clinical resolution after the introduction of methotrexate. The authors emphasize the importance of recognizing possible systemic reactions associated with the topical use of imiquimod.

Keywords: Aminoquinolines; Drug eruptions; Keratosis, actinic; Methotrexate; Pityriasis rubra pilaris.

Figure 1

Eruptive erythematous papulosquamous lesions on the trunk and cephalic segment.

Figure 2

Confluence of the lesions and evolution to erythroderma, with areas of healthy skin. Note the palmar involvement with orange keratoderma.

Figure 3

Skin, abdominal region, panoramic view: (A) hyperkeratosis, psoriasiform acanthosis, and moderate superficial perivascular lymphoid infiltrate; (B) detail of the previous image – there is altered hyperparakeratosis; (C) area of acantholytic dyskeratosis and supra-basal intraepidermal cleft; (D) marked congestion (arrow) with transepidermal elimination of red blood cells. Hematoxylin & eosin, original magnification of 100× (A) and 400× (B–D).

Figure 4

Disease resolution after nine months.