Denosumab-Induced Alopecia Areata with Lichenoid Eruption

The document discusses a case of a 71-year-old woman who developed alopecia areata (AA) and lichen planus (LP) after receiving denosumab, a biologic agent used for osteoporosis. The patient experienced rapidly progressive, patchy, nonscarring hair loss and skin lesions two months after receiving a 60-mg subcutaneous dose of denosumab. The patient's second dose of denosumab was held due to severe symptoms related to LP. After discontinuing denosumab and starting on topical 0.05% augmented betamethasone twice daily for AA and LP, the patient showed resolution of lichenoid papules and hair regrowth, with complete recovery in June 2020. The authors hypothesize a link between the induction of LP and AA and the use of denosumab, based on previous reports describing lichenoid eruptions, and instances of alopecia within weeks of starting denosumab. They suggest that the RANKL-RANK axis, which denosumab targets, may play a role in regulating immunity and thus contribute to these conditions.