Supplementary Material for: Acanthosis Nigricans in a patient with urothelial carcinoma treated with PD-L1 inhibitor Avelumab, and secondary adrenal insufficiency

Acanthosis Nigricans (AN) describes a hyperkeratotic and hyperpigmented skin changes and its pathophysiology is linked to activation of epidermal growth factor receptors. Current literature shows AN is most commonly diagnosed at time of the underlying pathology, which may occur in benign or malignant conditions. This case presentation demonstrates occurrence of AN following diagnosis of urothelial carcinoma and ongoing treatment with PD-L1 inhibitor immunotherapy. Subsequent investigations ruled out a secondary malignancy or disease progression, however metabolic screening identified secondary glucocorticoid-induced adrenal insufficiency. AN was persistent in this patient despite adequate treatment, which highlights its co-occurrence in both benign and paraneoplastic conditions.