A Rare Manifestation of Hypothyroid Myopathy: Hoffmann's Syndrome

Abstract

Hypothyroid myopathy is observed frequently and the resolution of the clinical manifestations of myopathy following thyroid hormone replacement is well known. However, a specific subtype of hypothyroid myopathy, Hoffmann's syndrome, characterized by increased muscular mass (pseudohypertrophy), proximal muscle weakness, muscle stiffness and cramps, is rarely reported. Herein, we describe a 34-year-old male who presented with proximal muscle weakness and non-pitting edema of the lower extremities. He initially visited the neurology department where he was suspected of having polymyositis. Additional laboratory evaluation revealed profound autoimmune hypothyroidism and elevated muscle enzymes including creatine kinase. The patient was started on levothyroxine treatment and, subsequently, clinical symptoms and biochemical parameters resolved with the treatment. The present case highlights that hypothyroidism should be considered in the differential diagnosis of musculoskeletal symptoms even in the absence of overt manifestations of hypothyroidism. To our knowledge, this is the first case reported in Korea.

Keywords: Creatine kinase; Hypothyroidism; Muscular diseases.

Fig. 1. (A) Puffy face and preorbital swelling. (B) Edematous hands and lower legs. (C) Non-pitting edema of the lower extremities and hypertrophy of the calf muscles, with skin changes (dry coarse skin and hyperpigmentation). These photos were taken after obtaining prior consent from the patient.

Fig. 2. (A, B) Neck ultrasonography showed atrophied thyroid gland with no definite nodular lesions.

Fig. 3. Electromyography showed mild spontaneous activity and short amplitude with polyphasic myopathic motor unit potential.

Fig. 4. Magnetic resonance imaging of the lower extremities shows symmetric multifocal patchy muscle enhancements with diffuse muscle swelling in both lower legs (superficial posterior compartment). Hypertrophy of the gastrocnemius; affected muscles show hyperintensity on T2-weighted images (arrows).