Thyroid storm triggered by perianal abscess: clinical overlap with severe thyrotoxicosis.

Thyroid storm is a rare and potentially fatal endocrine emergency, most commonly precipitated by infections, withdrawal of antithyroid drugs, or acute events in patients with Graves disease. Reports associated with thyroiditis or with unusual infections, such as perianal abscess, are exceptionally uncommon. We describe the case of a 61-year-old previously healthy man admitted with a perianal abscess complicated by atrial fibrillation with rapid ventricular response and thyroid storm. The patient received intensive treatment with propylthiouracil, Lugol solution, propranolol, corticosteroids, antibiotics, and electrical cardioversion, resulting in sustained reversion to sinus rhythm. During follow-up, he developed permanent hypothyroidism, requiring levothyroxine replacement. Beyond the perianal infection as an evident trigger, the progression to definitive hypothyroidism and positive antithyroid peroxidase antibodies also raises the uncommon possibility of hashitoxicosis as the underlying etiology. This case illustrates an atypical presentation of thyroid storm, underscoring the importance of early recognition and multidisciplinary management.