Extracervical fibrosclerosis causing obstruction of a ventriculo-peritoneal shunt in a patient with hydrocephalus and invasive fibrous thyroiditis (Riedel's struma).

The association of invasive fibrous thyroiditis (IFT) with foci of extracervical fibrosclerosis is well recognized. Affected sites include the retroperitoneum, the mediastinum, the biliary tract, and the orbit. The development of subcutaneous fibrosclerosis, however, is extremely rare. We report a patient with known invasive fibrous thyroiditis and hypoparathyroidism who presented with localized subcutaneous fibrosclerosis of the anterior chest wall resulting in compression of his ventriculoperitoneal shunt. The aetiology of IFT has remained unclear. Several histological and serological features, including the presence of mononuclear cells within the fibrosclerotic process, the occurrence of microscopic vasculitis, and the detection of autoantibodies directed against thyroid-specific antigens in a large proportion of patients with IFT, currently support the notion of autoimmune mechanisms playing a role in the pathogenesis of this rare disease.