Acrodermatitis continua of Hallopeau and geographic tongue are variants of pustular psoriasis

To the Editor: A recent article by Barron¹ reported the successful use of secukinumab to treat acrodermatitis continua of Hallopeau (ACH) and oral psoriasis. The author described a patient with pustulation of the distal fingertips and an erosive mucositis predominantly affecting the tongue, also involving the hard and soft palate and gingiva, which she distinguishes from geographic tongue (GT).

On review of the images, however, the patient had smooth bright red depapillation of the dorsum of the tongue with a slightly raised white serpiginous border consistent with the classical description of geographic tongue.² She also had involvement of the buccal mucosa and gingiva, which can also, although less commonly, be found in severe cases of GT.³ The association between pustular psoriasis and GT is well established.⁴ Recently, the molecular mechanisms underlying geographic tongue have been elucidated.⁵ Liang and colleagues⁵ identified mutations in the IL36RN gene, (encoding the interleukin-36 receptor antagonist), in patients with familial GT not associated with pustular psoriasis, in sporadic cases of GT, and in patients with GT associated with generalized pustular psoriasis, and proposed that GT be considered a localized manifestation of pustular psoriasis or a clinical phenotype of deficiency of IL36Ra (DITRA). Additionally, patients with GT lacking mutations in IL36RN were found to have impaired IL36Ra expression in tongue tissue. A proportion of patients with ACH, a localized form of pustular psoriasis, carry mutations in the IL36RN gene.⁶ I believe that the patient described by Barron has clinical manifestations of DITRA and suggest screening her for an IL36RN gene mutation.