Generalized annular pustular psoriasis (Milian-Katchoura type) induced by systemic steroids.

The aim of my clinical image is to recall this rare and benign form of pustular psoriasis and to insist on the role of the triggers of pustular psoriasis, mainly the drugs.

CLINICAL IMAGE

Pustular psoriasis is a rare, acute form of psoriasis. It can be triggered by pregnancy, infection, hypocalcemia, and medications. We describe a case of annular pustular psoriasis Milian‐Katchoura type, a rare variant of pustular psoriasis, that occurred secondary to reducing the dose of oral corticosteroids.

A 56‐year‐old female patient with a 5‐year history of plaque psoriasis treated with topical corticosteroids and phototherapy was admitted to the Department of Dermatology for a generalized rash 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 (Figure 1), with peripheral micropustules. The polycyclic plaques were paler centrally surrounded by a 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.

FIGURE 1

Annular erythematous and squamous lesions

FIGURE 2

Polycyclic pustular and papular lesions with trailing scale

Histopathological examination revealed a subcorneal spongiform pustule, acanthosis with hyperkeratosis, and parakeratosis. In the dermis, there was a mononuclear and neutrophilic infiltrate (Figure 3).

FIGURE 3

Subcorneal spongiform pustule, with a mononuclear and neutrophilic infiltrate in the dermis (hematoxylin and eosin ×200)

The diagnosis of generalized annular pustular psoriasis (Milian‐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/day with total regression of lesions.

Annular pustular psoriasis, described by Milian and Katchoura in 1933, is a rare form of pustular psoriasis. Pustular psoriasis may be induced or worsened by some factors primary drugs such as lithium, beta‐blockers, terbinafine, biotherapy, hydroxychloroquine, and a rapid withdraw of oral corticosteroids. , Although the pathomechanisms remain unknown, immunogenetic and molecular analysis demonstrated the existence of a mutation altering the synthesis and function of a natural IL‐36 antagonist (DITRA) leading to neutrophil chemotaxis and pustule formation. To avoid serious complications such as the occurrence of pustular forms of psoriasis, systemic corticosteroids should be prescribed with great caution to the patients.

CONFLICT OF INTEREST

None declared.

AUTHOR CONTRIBUTIONS

MEJ: is a corresponding author of the manuscript. AND: wrote the manuscript. AM and FZC: involved in photograph taking. AB: contributed to histological examination.SC: supervised the manuscript.

ETHICAL APPROVAL

Consent was obtained from the patient for publication and use of the images.