Vol 3 | Issue 1 | Jan – July 2017 | page:11-13 | Kumar Premjeet Madhukar, Lakin Vira, Nilay Chakrabarti, Shalaka Indap, Smita Sawant, Janhavi Kapadia
Authors : Kumar Premjeet Madhukar , Lakin Vira , Nilay Chakrabarti , Shalaka Indap , Smita Sawant , Janhavi Kapadia 
 Departments of Surgery and Pathology, K.J. Somaiya Medical College & Hospital, Mumbai, India 400022.
Address of Correspondence
Dr. Lakin Vira,
Departments of Surgery and Pathology,
K. J. Somaiya Medical College & Hospital, Mumbai, 400022.
Riedel’s thyroiditis is a rare fibrosclerotic infiltrative thyroid disorder of unclear etiology in which normal thyroid tissue is replaced by fibrous tissue, often extending outside the thyroid capsule. The diagnosis can be difficult to establish prior to surgical removal of the thyroid and is only possible subsequent histopathological examination of the resected gland. Here we present a rare case of Riedel’s thyroiditis.
Key words: Riedel’s thyroiditis, thyroid inflammation, rare thyroid lesions.
Riedel’s thyroiditis, also called Riedel’s struma is a rare and chronic form of thyroiditis. This fibrosis may extend to adjacent structures of the neck, thereby mimicking a thyroid malignancy. Patients usually present with complaints of dyspnoea, dysphagia and hoarseness of voice. These features are due to the involvement of adjacent structures in the fibrotic process and also due to tracheal compression .
A 45 year old male presented to the out patient department with a swelling over the neck since 5 years accompanied by epidodes of fever. The patient was a known diabetic and hypertensive, controlled with medications. The swelling over the neck had rapidly increased in size in the past 1 month and the episodes of fever had become more frequent. On clinical examination, the swelling moved upwards with deglutition, was 5×4 cms in size and hard in consistency. There were no clinical features to suggest a possible retrosternal goiter and no cervical lymphadenopathy. Routine biochemical investigations were unremarkable, except for raised total leucocyte count (13,500/mm3) with the patient in the euthyroid state. Ultrasonography of the neck revealed a multinodular goiter involving the left side with a normal right lobe and fine needle aspiration cytology was reported as a colloid goitre. Indirect laryngoscopy was normal. Patient was admitted and started on intravenous antibiotics for a week following which he was then taken up for left hemi thyroidectomy after obtaining medical and anaesthesia fitness. Intraoperatively, the gland was fibrous and there were dense adhesions of thyroid to the surrounding structures with loss of tissue planes. The left lobe of thyroid showed a single solitary nodule of size approx 3 x 3 cms while the right lobe of thyroid was unremarkable. Hence, a decision was made to go ahead with left hemithyroidectomy, for which the gland had to be separated with difficulty and extreme caution from the carotid sheath which had become encased due to dense adhesions. Frozen section facilities not being available at that point in time, this appeared to be the best course of action for the patient keeping in mind the possibility of a subsequent total thyroidectomy in case of diagnosis of malignancy on histopathology. Post op recovery of the patient was uneventful. Histopathological reports were suggestive of Riedel’s thyroiditis. Hence no further surgical intervention was carried out.
Riedel’s thyroiditis is named after Bernhard Riedel who first recognized the disease in 1883 and reported it in 1896 . Riedel used the term “Eisenharte Struma” to describe the stony hard consistency of the thyroid gland and its fixity to adjacent structures. Riedel’s thyroiditis is extremely rare with an approximate incidence of 1.06/100,000 . It involves a possible autoimmune inflammation and fibrosis of the thyroid gland and its surrounding tissues, with distant organs being sometimes also involved. This presentation, and the presence of IgG4+ plasma cells and thyroidal autoantibodies in some patients suffering from Riedel’s thyroiditis led some authors to consider Riedel’s thyroiditis as part of multifocal fibrosclerosis, linking it to the IgG4– sclerosing disease group . Riedel’s thyroiditis is a rare disease that most commonly occurs in females in their fifties and usually presents as a diffuse goitre without clinical evidence of thyroid nodules. On palpation, the thyroid demonstrates firm or stony consistency (“iron-hard thyroiditis”) . Symptoms of regional compression may progressively appear. However, the clinical course of this disease is mostly variable and may include cases with no thyroid-related symptoms, as we have noted in our patient. Before surgery, Riedel’s thyroiditis is often difficult to differentiate from aggressive types of thyroid cancers i.e., undifferentiated thyroid carcinoma; however, a long-term follow-up shows no disease-specific mortality . A number of hypotheses have been proposed regarding etiology and pathogenesis of Riedel’s thyroiditis. The disease may be associated with subacute and chronic thyroiditis; thus some authors proposed the an “intrathyroidal hypothesis”. According to that hypothesis, the entity may represent the late stage of a chronic inflammatory disorder that has progressed to fibrotic stage . On the contrary, the “pharmacological hypothesis” suggests that some particular medications may trigger the development of Riedel’s thyroiditis. Although it has not been proved, a genetic susceptibility and subsequent development of the condition was also hypothesized. However, the “systemic autoimmune hypothesis” seems to have the most support now, and which believes Riedel’s thyroiditis to be a manifestation of disordered fibroplastic proliferation because of a hypersensivity reaction with subsequent release of stimulating growth factors . Ultrasonographic evaluation of a suspected case of Riedel’s thyroiditis shows a hypo-echoic and hypo-vascular mass with extension into adjacent soft tissues. However, this appearance is nonspecific and can be seen in other disease processes that present with diffuse fibrotic involvement, such as Hashimoto’s thyroiditis, lymphoma, and malignancy of the thyroid thus making it difficult to distinguish Riedel’s thyroiditis from other forms of thyroiditis. Although the most important diagnostic tool for thyroid disease is FNAC under ultrasonographic guidance, Riedel’s thyroiditis can rarely be diagnosed accurately by pre- operative cytology . The extent of fibrosis and compression of the trachea and/or esophagus is easily defined by CT, with the thyroid appearing hypo-dense to normal, and invasion of nearby tissues may be observed . Despite the various imaging techniques used, surgeons are often still unable to differentiate Riedel’s thyroiditis from other thyroid pathologies such as neoplasms and its diagnosis remains based on surgical biopsy . The features seen in Riedel’s thyoiditis would include an inflammatory process in the thyroid extending into the surrounding tissues but without giant cells, lymphoid follicles, oncocytes or granulomas , evidence of occlusive phlebitis, and quite clearly, no evidence of malignancy . After diagnosis, the conservative treatment of Riedel’s thyroiditis includes corticosteroids and tamoxifen. Surgery may be performed in order to relieve tracheal or esophageal compression, although extensive surgery is not recommended and complete resection of the thyroid gland is almost always difficult to achieve. In our case, left hemithyroidectomy was possible and hence performed.
The case we present here shows that there is still a lack of knowledge on Riedel’s thyroiditis, especially about its accurate preoperative diagnosis with no specific diagnostic markers that can raise a suspicion about the condition which can then help plan treatment. The differences between the results of the imaging examinations of different cases of Riedel’s thyroiditis, the presence or absence of thyroidal autoantibodies, and its association with another thyroidal disease or fibrotic entity, as well as the different responses to medical treatment as reported in literature raise the question of a possible staging of Riedel’s thyroiditis. This would warrant further research . The fact that we were able to do a left hemithyroidectomy could in fact be due to the an early stage of the disease and could add some weight to the necessity of developing such a staging system. Another extremely important point remains the differential diagnosis of Riedel’s thyroiditis. Because of the its overlap with malignancy, including the possible co-occurrence of these pathologies or the risk of one mimicking the other, efforts must be done in improving preoperative diagnosis of Riedel’s thyroiditis, using either fine-needle aspiration or imaging.
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|How to Cite this Article: Madhukar K P, Vira L, Chakrabarti N, Indap S, Sawant S, Kapadia J. Riedel’s Thyroiditis – A Clinical Enigma. International Journal of Surgical Cases 2017 Jan-July;3(1): 11-13.|