Amyloid goiter presented as a subacute thyroiditis-like symptom in a patient with hypersensitivity vasculitis

We present a 25-year-old woman with amyloid goiter due to hypersensitivity vasculitis, who developed transient thyrotoxicosis resembling subacute thyroiditis. She received prednisolone (20 mg/ day) for three years for hypersensitivity vasculitis, and was diagnosed as having secondary amyloidosis by biopsies of the stomach, rectum and kidneys. She noticed neck swelling with severe right neck tenderness, palpitation, hyperhidrosis and weight loss. An elastic firm diffuse goiter was palpable, and the upper pole of the right lobe was extremely tender. Her serum free T4 and T3 levels were high, and the serum TSH was suppressed to subnormal. She was positive for serum C-reactive protein. Anti-thyroidal autoantibodies were all negative. Her thyrotoxicosis subsided spontaneously within one week. Serum titers of antibodies to various viruses were unchanged during the clinical course for two weeks, but she was positive for HLA B35. Examination of a needle-biopsy specimen of the thyroid gland showed extensive amyloid deposition and no evidence of subacute thyroiditis. We considered her transient thyrotoxicosis to be associated with amyloid goiter. The clinical course of this case was similar to the subacute thyroiditis-like syndrome, first described by Ikenoue et al. When patients with primary or secondary amyloidosis have symptoms and signs of subacute thyroiditis, but develop an unusual course, amyloid goiter should be considered.