PSUN42 New-Onset Rheumatoid Arthritis After Surgical Treatment of Cushing Syndrome

BACKGROUND: Cushing syndrome (CS) is a rare endocrinopathy resulting from prolonged exposure to endogenous or exogenous glucocorticoids. CS can be subclinical or can present with an array of overt signs and symptoms. The goal of treatment in CS is to reestablish normal cortisol levels in the body by eliminating the source of excess cortisol. Autoimmune diseases are often treated successfully with exogenous glucocorticoids. There are several case reports/series in the literature describing patients who developed autoimmune diseases, or experienced recrudescence of otherwise quiescent autoimmune processes, after the withdrawal of glucocorticoids. Such diseases include rheumatoid arthritis, Graves disease, Hashimoto's thyroiditis, systemic lupus erythematosus, psoriasis, and myasthenia gravis. Below we share a case of rheumatoid arthritis that presented after unilateral adrenalectomy for CS. CLINICAL CASE: A 55 year old female with a history of Graves disease status post radioactive iodine ablation many years ago with post-ablative hypothyroidism was found to have a left adrenal mass on CT in 2016. An MRI in February 2021 showed interval growth from 3.8×2.9×3.6cm to 5.1×3.5×4.8cm. ACTH was suppressed to <1.5 pg/mL (7.2-63.3 pg/mL), 24 hour urine free cortisol was elevated to 256 ug/24hr (10-34 ug/24hr), midnight salivary cortisol was elevated to 219 ng/dL then 430 ng/dL on repeat (n<100 ng/dL), and AM cortisol was 13.7 ug/dL (6.0-18.4 ug/dL) after 1mg overnight dexamethasone administration. This biochemical testing was supportive of the diagnosis of ACTH-independent adrenal CS. Our patient underwent successful left adrenalectomy in March 2021 and was started on hydrocortisone postoperatively given long-standing suppression of her hypothalamic-pituitary-adrenal axis. Within three months, she developed muscle aches and pain in bilateral hands, ankles and feet with stiffness and swelling. These symptoms worsened with glucocorticoid taper. She was found to have a rheumatoid factor of 32 IU/mL (0-13 IU/mL) and was diagnosed with rheumatoid arthritis, for which she was started on hydroxychloroquine and briefly switched from hydrocortisone to prednisone. She has since been tapered off steroids with resolution of adrenal insufficiency. Her rheumatoid arthritis symptoms remain adequately controlled on hydroxychloroquine. CONCLUSIONS: While it is known that withdrawal of exogenous chronic steroids can result in exacerbation of pre-existing autoimmune disease, the emergence of new autoimmune disease upon withdrawal of endogenous steroid production after treatment of pituitary ACTH-dependent or adrenal ACTH-independent CS is extremely rare. Of special interest, our patient described above had a history of Graves disease years before her CS diagnosis was made, suggesting an underlying proclivity towards autoimmunity. Further study may reveal the need for higher vigilance in postoperative monitoring in patients with preexisting autoimmune conditions. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.