CHRONIC THYROIDITIS AND RIEDEL'S STRUMA: ETIOLOGY AND PATHOGENESIS. THE ROLE OF THE HYPERFUNCTIONING PARENCHYMA OF PRIMARY HYPERPLASTIC GOITER*

Abstract

Exten-sive review of the literature has failed to reveal the etiology of chronic thyroiditis and Riedel''s struma. The material consisted of thyroid tissue from thyroidectomies on patients with hyper-plastic goiter showing varying degrees of chronic thyroiditis. Hyperfunctioning epithelial cells were identified by increased content of mitochondria whereas cellular hypofunction was indicated by diminished numbers of mitochondria in the cytoplasm. Chronic nonspecific thyroiditis is an inflammatory response to etiologic irritative factors residing in the hyper-functioning epithelium of primary hyperplastic goiter. In its incipiency this response is characterized by circumscription, isolation and progressive destruction of numerous irritative foci of hyperfunctioning parenchyma by the lytic action of lymphoid and plasma cells. Irritative qualities of hyperfunctioning follicles exert positive chemotaxia upon the lymphoid and plasma. Gradually new foci of hypertrophic epithelium appear following which the inflammatory cycle is repeated. The bulk of hypertrophic parenchyma is correspondingly reduced. In this manner clinical phases of hypothyroidism are produced. Patients in the earlier phases of chronic thyroiditis all suffered with hyperthyroidism, while in the later phases of hypothyroidism the thyroid parenchyma was largely destroyed. A history of antecedent hyperthyroidism was obtained even in patients in the late phases of chronic thyroiditis. Our findings appear to support the view that Riedel''s struma is the end result of successive phases of chronic non-specific thyroiditis.