Hoffmann’s Syndrome Mimicking Polymyositis Secondary to Hypothyroidism: A Case Report

Abstract

Background: Hoffmann’s syndrome is a rare and underdiagnosed form of hypothyroid myopathy that can closely mimic autoimmune inflammatory myopathies such as polymyositis, potentially leading to inappropriate immunosuppressive therapy. Case Presentation: A 39-year-old female with inadequately controlled hypothyroidism presented with progressive proximal muscle weakness for one year, worsening after a febrile illness. Examination revealed predominant proximal weakness, reduced left hand grip, and left-sided sensory deficits from C2. Laboratory findings included hyperCKemia (CPK 5810 U/L), elevated transaminases, and raised TSH (9.86 mIU/mL). ENMG showed myopathic changes. Initial suspicion of polymyositis led to corticosteroid therapy, but the diagnosis was revised to Hoffmann’s syndrome after negative autoimmune markers, characteristic ENMG findings, and rapid improvement with levothyroxine. Conclusion: This case highlights the importance of evaluating thyroid function in patients with proximal myopathy and hyperCKemia. Early levothyroxine replacement leads to significant recovery and avoids unnecessary immunosuppression. The concomitant periarticular osteopenia expands the clinical spectrum of long-standing hypothyroidism.