LAUSR

Dear Editor, Acrodermatitis continua of Hallopeau (ACH) is an uncommon chronic, inflammatory, and relapsing disease manifesting as sterile pustules of the fingers and toes with possible involvement of nail bed. ACH is often refractory to treatment and no standardized guidelines exist for its therapy (Crowley, Maliyar, Rodriguez-Bolanos, O'Toole, & Gooderham, 2019). Several case reports described the efficacy of different biologics in ACH, but to date no evidence is available for adalimumab biosimilar (Passante, Dastoli, Nisticò, Bennardo, & Patruno, 2020). We reported a case of ACH in a young patient, successfully treated with adalimumab biosimilar. A 15-year-old female presented with a 6-month history of a pustular eruption of the toe of the right foot. Physical examination showed erythema, pustules, erosions, and crusting involving the nail and perionychium with severe onychodystrophy (Figure 1a). The patient related that the lesions were associated with severe pain, with consequent loss of function and impairment in daily activities. The patient had no family history of psoriasis and her medical history was unremarkable. Laboratory tests including hepatitis B and C serology, antinuclear antibody (ANA), QuantiFERON tuberculosis test were normal and were within normal ranges except for C-reactive protein (CRP) (0.97 ng/mL, n.v. 0-0.50 mg/dL) and erythrocyte sedimentation rate (25 mm/hr, n.v. <15 mm/hr). Microbiological examination of pustules was negative. X-ray examination revealed no osteolytic changes of the bones and no joint deformities. A 3-mm skin punch biopsy showed psoriasiform hyperplasia, parakeratosis, numerous neutrophils (Munro-like microabscesses), and focal spongiosis with severe reduction of granular layer with increased vascularity within the dermal papillae being observed. Based on clinical, histological, and laboratory data, an ACH diagnosis was performed. Topical agents (0.05% clobetasol propionate), and 8 weeks of oral cyclosporine (2.5 mg/kg/die) lead only to moderate and transitory results. Therefore, treatment with adalimumab biosimilar (a human antitumor necrosis factor[TNF]α) was started (40 mg every 2 weeks) leading to a complete resolution of skin and nail lesions in 3 months (Figure 1b) without any side effects and with a huge improvement of her quality of life. At 9 months follow-up, the patient is still under control and no further lesions appeared (Figure 1c). ACH pathophysiology is not yet totally understood. Commonly ACH has been reported in middle-aged women, after localized trauma, for Koebner's phenomenon, to a single digit with subsequent proximal spread (Di Costanzo, Napolitano, Patruno, Cantelli, & Balato, 2014). Treatment is considered a challenge for the dermatologist because of relapsing trend, resistance to therapies, and lack of therapeutic recommendations. As ACH is a rare occurrence in childhood, in this age group management is even more difficult because many options have drawbacks or are not approved (Alorainy, Alshaya, Al-Rikabi, Ayesh, & Alsaif, 2017).