Marked Improvement of Palmoplantar Pustulosis After the Reintroduction of Apremilast Following Initiation of Dental Infection Control and Periodontal Therapy.

Palmoplantar pustulosis (PPP) is a chronic inflammatory disorder characterized by recurrent sterile pustules, erythema, scaling, and hyperkeratosis on the palms and soles. Oral infectious foci and periodontal inflammation have been implicated as aggravating factors, particularly in Japanese patients. We report the case of a 60-year-old woman with longstanding PPP and a previous course of apremilast that she had discontinued because of perceived insufficient benefit. At presentation, the Palmoplantar Pustulosis Area and Severity Index (PPPASI) score was 37.8. Dental evaluation identified multiple periapical lesions, an endodontic-periodontal lesion, and generalized periodontitis, Stage III, Grade C. During initial periodontal therapy, including oral hygiene instruction and supragingival scaling, the periodontal inflamed surface area decreased from 1,894.5 to 558.8 mm², and the PPPASI score decreased to 20.5 approximately six months after the initiation of dental treatment, corresponding to a 45.8% improvement that did not meet the PPPASI-50 threshold. At that time, apremilast had not yet been reintroduced, and definitive endodontic treatment had not been completed; root canal treatment of tooth 47 was initiated at approximately month six and completed at month eight. Because residual PPP persisted and subsequent improvement slowed, apremilast was reintroduced approximately two months after the month six assessment at 30 mg/day. Two days later, transient acute urticaria occurred, and apremilast was temporarily interrupted. The eruption resolved by the following day without additional treatment or systemic hypersensitivity features. Because of the patient's previous history of urticaria and the absence of recurrence after rechallenge, the episode was considered unlikely to represent apremilast hypersensitivity. Apremilast was restarted at 30 mg/day, and approximately 2.5 months after the reintroduction, the PPPASI score had decreased to 6.1, corresponding to an 83.9% improvement from baseline and achievement of PPPASI-75. This single case provides a hypothesis-generating observation that reduction in periodontal inflammatory burden was temporally associated with partial improvement before apremilast reintroduction, after which further marked improvement was observed. Evaluation and management of oral infectious foci and periodontal inflammation may therefore be considered an adjunctive strategy in selected patients with PPP who have a suboptimal response to systemic therapy, particularly when clinically or radiographically evident oral disease is present.