ABSTRACT
Cidofovir is well described as an effective antiviral agent. It is reported to treat viral warts successfully in immunocompetent and immunocompromised individuals. Unfortunately, its use may be limited by the high cost and pain of treatment. We here report the successful treatment of multiple palmoplantar warts in an 8-year old male undergoing chemotherapy for relapsed acute lymphoblastic leukaemia. His most significant lesion was a 3 x 3 x 1.5 cm tumorous lesion on the central plantar forefoot that interfered with weight bearing. It had been resistant to over-the-counter treatments, cryotherapy, silver nitrate cautery, curettage and cautery, cantharadin and topical 5-fluorouracil. He was developing multiple satellite lesions and they had spread to the toes, the other foot and both hands, totalling more than 30 lesions. The first treatment session was during sedation for intrathecal chemotherapy. One millilitre of cidofovir (diluted to 15 mg mL-1) was instilled to the largest lesion (although solution was seen visibly escaping from the surface). The remainder of the vial was compounded to topical cidofovir 1% in Eucerin, which he applied once daily to remaining lesions. His postprocedure recovery was unremarkable, with no analgesia requirements or other complications. By the time of review 4 weeks later, the verruca that had received one session of intralesional treatment had completely resolved. Some of the smaller warts had shrunk in size. Despite reports of pain associated with intralesional cidofovir injections, our patient was keen for a repeated treatment to more lesions without sedation/anaesthetic. He tolerated the treatment of a number of remaining lesions without the need for topical or local anaesthesia. Treatments continued at 4-weekly intervals (to coincide with his chemotherapy regimen) with good response and no side-effects. After three treatment sessions most lesions had resolved with only some smaller lesions remaining. Unfortunately, his next treatments were suspended as he contracted COVID-19. In summary, we report the successful eradication of significant and widespread viral warts in an immunocompromised paediatric patient. Reports in patients under 10 years of age are scarce. We also confirm excellent tolerance of the procedure. Although the high cost of cidofovir may seem prohibitive, given that one vial could generate around 25 mL solution and 0.2-1 mL is needed per lesion, we would argue that it may be more costeffective than multiple sessions of other less/ineffective modalities. Furthermore, its antiviral mechanism of action is particularly beneficial in immunocompromised patients in comparison with other modalities, which require an efficient immune response in order to be successful.