Voriconazole-induced arthritis, enthesitis and periostitis

Voriconazole is a fluoride-containing anti-fungal. Prolonged exposure can result in fluoride deposition within the bone extracellular matrix, resulting in periostitis and arthritis. We report a patient who developed widespread bony pain and polyarthralgia while on voriconazole therapy for COVID-19-associated pulmonary aspergillosis. No associated autoimmune rheumatic disease or alternative cause was noted. Blood investigations showed elevated total serum alkaline phosphatase, bone-specific ALP and fluoride levels, with normal serum voriconazole levels. A whole body nuclear bone scan showed multifocal periostitis. A diagnosis of voriconazole-induced periostitis and arthritis was made. Complete resolution of clinical symptoms with normalisation of the serum ALP occurred within four weeks of voriconazole cessation. While voriconazole-induced periostitis/arthritis is a recognised phenomenon in solid organ and haematopoietic stem cell transplant patients on long-term voriconazole, this case highlights the importance of having a high index of suspicion in other settings including CAPA. Clinical presentation can be mistaken for bony metastatic disease or other inflammatory arthritis.