Endogenous hypercortisolism is a well-known immunosuppressive condition. Such endogenous cortisol secretion could suppress the clinical presentation of an ongoing autoimmune process. Autoimmune diseases in patients have flared after the curative surgical treatment of cortisol-producing adenomas. We report a case with Hashimoto thyroiditis that progressed to localized necrotizing vasculitis of the female genitalia that moderately worsened after the surgical removal of an adrenal adenoma associated with subclinical Cushing disease. The endogenous hypercortisolism from an adrenal adenoma seemed to mask the "systemic" presentation of a concurrent vasculitis, leading to a misdiagnosis of "focal vasculitis."