Clinical image:
A 56 years old female patient with a 5-year history of plaque psoriasis treated with topical corticostreoids and phototherapy was admitted to the Department of Dermatology for a generalized rush which appeared after she reduced the dose of an oral treatment based on 60 mg of prednisone. Dermatological examination revealed well-demarcated, large, annular erythematous and squamous lesions (Figure1), with peripheral micro- pustules. The polycyclic plaques was paler centrally surrounded by raised ring, confluent numerous pustules with trailing scale (Figure 2). The patient had no systemic symptoms or fever. Laboratory tests revealed a biological inflammatory syndrome with a normal calcemia and a sterile pustule at the bacterial sampling. Several diagnostics have been suggested: acute generalized exanthematous pustulosis, annular pustular psoriasis and subcorneal pustular dermatosis.
Histopathological examination revealed a subcorneal spongiform pustule, acanthosis with hyperkeratosis and parakeratosis. In the dermis, there was a mononuclear cells and neutrophils infiltrate (Figure3).
The diagnosis of generelized annular pustular psoriasis (Millian Katchoura type) was retained because of the personal history of psoriasis, the evocative clinical aspect, and the histological findings. The patient was treated with acitretin 10 mg/ kg/ day with a total regression of lesions.
Annular pustular psoriasis, described by Milian and Katchoura in 1933, is a rare form of pustular psoriasis. The pustular psoriasis may be induced or worsen by a number of factors primarily drugs such as lithium, beta blockers, terbinafine, biotherapy, hydroxychloroquine and a rapid taper of oral corticosteroids (1, 2). In order to avoid serious complications such as the occurrence of pustular forms of psoriasis, systemic corticosteroids should be prescribed with great caution to the patients.
Legends:
Figure1: Annular erythematous and squamous lesions
Figure2: Poly-cyclic pustular and papular lesions with trailing scale
Figure 3: subcorneal spongiform pustule, a mononuclear and neutrophils cell infiltrate the dermis (Hematoxylin and eosin x200)
Reference :
Westphal DC, Schettini APM, Souza PP, Castiel J, Chirano CA, Santos M. Generalized pustular psoriasis induced by systemic steroid dose reduction. An Bras Dermatol. 2016;91(5):664-6.
Du-Thanh A, Girard C, Pageaux GP, Guillot B, Dereure O. Sorafenib-induced annular pustular psoriasis (Milian-Katchoura type). EJD, vol. 23, n◦ 6, November-December 2013