J.Jpn. Surg. Soc.. 59(11): 1749-1759, 1959

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STUDIES ON THYROIDITIS

Riedel's struma, subacute nonsuppurative thyroiditis, Hashimoto's struma and acute suppurative thyroiclitis are all regarded as nonspecific inflammation of the thyroid gland. No unanimous theory, however, has ever been established in regard to the pathological differences among these diseases, especially among the first three. In order to investigate the pathogenesis of subacute thyroiditis, Riedel's struma and Hashimoto's struma, the clinical and pathological studies were performed on thirty-five cases which were diagnosed histologically among sixty-eight patients of thyroiditis treated in our clinic from April 1953 to July 1957. The results obtained in the present studies are as follows:
Clinical data.
In most of the patients of subacute thyroiditis, pharyngitis, tonsillitis and other inflammations of uper respiratory tract were observed prior to the onset of the painful enlargement of the thyroid gland. the thyraid gland is frequently involved on one of its lobes and sometimes on both the ones, and symptoms of hyperthyroidism are coincidentally present in this disease. In general, these symptoms of subacute thyroiditis are improved rather rapidly, but sometimes a hard painless goiter, which is similar in many respects to Riedel's struma, remains. Also in cases of Riedel's struma the goiter, which has sometimes slight tenderness, follows frequently slight fever and inflammation of the upper respiratory tract. Thus, when the clinical symptoms of subacute thyroiditis have become chronic, it may be difficult to distinguish subacute thyroiditis from Riedel's struma.
On the other hand, Hashimoto's struma presents some features clinically different from those of subacute thyroiditis and Riedel's struma: Fever, sore throat and other prodromal symptoms are absent in the patients of Hashimoto's struma, the term of complaints of Hashimoto's struma continues longer in general than that of subacute thyroiditis and Riedel's struma, and the thyroid gland in most cases of Hashimoto's struma is enlarged bilaterally and diffusely, and has no inflammatory signs. And sometimes hypothyroidism is apt to be present in patients of Hashimoto's struma who have much long term of complaints. While the intensiv adherence between the thyroid gland and th adjacent t issues is observed at th operation in the cases of subacute thyroiditis and especially of Riedel's struma, the mild adherence is observ cl in the cases of Hashimoto's struma.
Laboratory data.
Red cell sedimentation rate is much elevated in the earlier stage of subacute thyroiditis, but it is gradually reduced to the normal level as in the case of Riedel's struma. In Hashimoto's struma red cell sedimentation rate does not show a constant tendency, sometimes elevated and sometimes reduced.
Serum PBI shows often a high level in the earlier stage of subacute thyroiditis, but in the course of time it comes to show the normal level as in the case of Riedel's struma. In most cases of Hashimoto's struma serum PBI value has a tendency to decrease gradually in the course of time, and in three of the ten cases of Hashimoto's struma the value is proved to be subnormal.
I¹³¹ thyroidal uptake ratio in subacute thyroiditis shows the normal or subnormal value, though serum PBI shows as high level. Either in Riedel's struma or Hashimoto's struma I¹³¹ uptake ratio seems to be almost parallel to serum PBI value.
Thus, subacute thyroiditis presents some special clinical appearances in its earlier stage, but it shows various clinical features closely similar to those of Riedel's struma, when it becomes chronic in the course of time. But Hashimoto's struma shows some clinical features quite different from those of subacute thyroiditis and Riedel's struma.
Microscopic examination.
The earliest lesions of subacute thyroiditis involve thyroid fo llicles : proliferation of epithelial cells, formation of giant cells, and decrease or disappearance of colloid in the follicular lumens are observed. Then immature granulomatous tissue proliferates in the perifollicular area, and follicles are gradually deformed finally replaced by the increased connective tissue. Thus, subacute thyroiditis shows similar histological findings to those of Riedel's struma in the course of time. On the other hand, in Hashimoto's struma such pathological findings as increase of the height, swelling and eosinophilia of epithelial cells, and decrease of intrafollicular colloid are observed at first. And then lymphocytic infiltration and lymph follicle formation in the stroma and proliferation of the interlobular connective tissue become prominent.
Though the histological findings of Hashimoto's struma res mble somewhat those of Riedel's struma, the former is quite different from the latter in appearances of epithelial cells and of proliferation of the connective tissue. Furthermore, in Hashimoto's struma the follicles are surrounded and are pressed by the interlobular connective tissue. When the follicles come to be unable to keep its structure on account of pressur of the interlobular connective tissue, the epithelial cells are isolated from the follicles and assume sometimes such appearances as that of a pseudo-giant cell. Whil the giant ells which have appeared in the earlier stage of subacute thyroiditis, have the colloidphagic activity, the pseudo-giant cells in Hashimoto's struma have not such an activity. That is to say, also in these histological findings Hashimoto's struma is quite different from subacute thyroiditis and Riedel's struma. In acute suppurative thyroiditis such pathological changes as polynuclear cell infiltration, necrosis, and abscess formation involve interlobular tissue and its follicular cells are scarecely damaged. The acute suppurative thyroiditis shows pathohistological findings quite different from those of subacute thyroiditis, Riedel's struma, and Hashimoto's struma.
Sammary
1. It may not be considered that subacute thyroiditis and Riedel's struma are different in entity. When some cases of subacute thyroiditis are prolonged in cure and become gradually chronic, they may transform into Riedel's struma.
2. Hashimoto's struma may be quite different in entity from subacute thyroiditis and Riedel's struma.
3. Acute suppurative thyroiditis is also different from other three types of thyroiditis in entity.
(author's abstract)

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