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PRIMARY THYROID TUBERCULOSIS
D Balasarkar*, MA Joshi**, J Dhareswar***, RR Satoskar****,N Awsare*****, R Mahey*****, V Kumar*
*Lecturer; **Asso Prof.; ***Senior Resident; ****Prof.; *****Resident; Dept. of Surgery, LTMMC and LTMGH, Sion, Mumbai - 400 022.
Primary thyroid tuberculosis is uncommon. Nowadays since extrapulmonary tuberculous involvement is seen more frequently, the existence of this condition should be recognised when goitres are being treated. A case of tuberculosis involving thyroid gland primarily is presented here. The manifestation of thyroid tuberculosis and its pathological types are discussed.INTRODUCTION
Tuberculosis of thyroid gland is extremely uncommon with very few cases reported in recent years. Symptom free thyroid involvement may occur as a part of generalised miliary spread or, more rarely, diffuse or localised swelling of the gland.[1] In most of the reported cases the patients have been clinically and biochemically euthyroid.[1] Because of unusual and rare presentation, suspicion of the thyroid nodule or swelling as being tuberculous on clinical examination is remote, unless it has destroyed much of the thyroid gland and had formed an abscess in a patient with known pulmonary tuberculosis, [2] or also when FNAC is positive for tuberculosis.[3]
CASE REPORT
A 27 year old female patient presented with slow, progressively increasing swelling over right side of midline of neck. On examination, there was a 3 cm x 2 cm nodule on right side of midline, which moved well with deglutition. Its surface was smooth and it was firm in consistency. The margins of the swelling were not well defined and were merging with the right lobe of thyroid gland. Rest of thyroid gland was normal. No symptoms of complications, or hypo or hyperthyroidism were present. A diagnosis of solitary nodule of right lobe of thyroid gland was made in a euthyroid patient. Investigations revealed a normal haemogram except a raised ESR of 55 mm. T3, T4, TSH levels were normal. X-ray chest was normal. USG of thyroid revealed a cystic swelling measuring 3 cm x 2 cm in the right lobe of the thyroid gland. FNAC of swelling was suggestive of colloid goitre. The patient was subjected to right hemithyroidectomy. She made an uneventful postoperative recovery. Histopathology report was suggestive of tuberculosis of thyroid gland. The patient was started on antituberculous drugs. Follow up over three months after operation was uneventful.
DISCUSSION
In the 19th century, it was authoritatively suggested that tuberculosis never involved the thyroid gland and that there was some antagonistic action between goitre and tuberculosis.[1] So that presence of thyroid swelling was proof that the patient did not have tuberculosis.[1] The relative immunity of the thyroid gland has been confirmed but has not been explained. Primary involvement of the thyroid gland is difficult to explain. The latent focus of infection perhaps is of great importance in the development of such type of extrapulmonary tuberculosis.[1] This is in contrast to the thyroid involvement associated with pulmonary or extrapulmonary tuberculosis, where spread of the disease occurs by haematogenous, or lymphogenous route or directly from larynx or tubercular cervical lymphadenitis and likely to occur when infection is progressive.[4]
Lebert (1862) reported the first case of tuberculous thyroid involvement in a patient with disseminated tuberculosis.[1] Chiari (1878) described 7 cases of microscopic involvement of thyroid in 100 autopsies of patients who had died from disseminated tuberculosis.[1] Sporadic reports followed in which there was miliary spread to the thyroid gland but no abnormality of thyroid was suspected clinically. Bruns in 1893 described the first case of tuberculous thyroiditis diagnosed in a middle aged woman with a rapidly enlarging goitre, who had cervical lymphadenopathy but no evidence of pulmonary tuberculosis.[1] The presenting patient had gradually enlarging goitre, without any cervical lymphadenopathy and pulmonary tuberculosis. The first report of successful drainage of tuberculous thyroid abscess was by Schwartz in 1894.[1] Five cases of thyroid tuberculosis were described by Coller and Huggins (1926) in a series of 1200 of thyroid operated.[5] Rankin and Graham (1932) studied a large series of 20758 partial thyroidectomy specimens from the Mayo Clinic between 1920 and 1931, only 21 cases of thyroid tuberculosis were diagnosed, an incidence of 0.1%.6 A similar incidence was confirmed more recently by Levitt (1952), who found only 2 cases of thyroid tuberculosis among 2114 consecutive thyroid specimen.[1] The rarity of condition in recent years is emphasised by Bolis (1970) who found 2 cases of fibrocaseous thyroid tuberculosis in 74393 consecutive thyroid biopsies in an Italian centre.[1] Only isolated clinical case reports are to be found in recent literature.[1] [2] [7] [8] [9]
Tuberculosis may involve thyroid gland in 2 main forms. The more common of these is miliary spread to thyroid gland as a part of generalised dissemination, but this form has never been shown to give rise to clinical thyroid disease.[6] Occasionally, miliary spread may occur in pre-existing thyroid enlargement.[5] Less commonly focal caseous tuberculosis of thyroid may occur, presenting as a localised swelling mimicking carcinoma,[1],[8] as cold abscess appearing superficially,6 very rarely as an acute abscess,[7],[9] or as a thyroid nodule as seen in presenting case. Fibrosis and adherence to adjacent structure may occasionally give rise to pressure symptoms like dysphagia, dyspnoea[4] or recurrent laryngeal nerve palsy.[1] Microscopically there is destruction of thyroid tissue with caseating tuberculosis granulomata. Thyroid tuberculosis can be distinguished from sarcoidosis[10] and subacute (giant cell) thyroiditis[11] by the presence of caseation and demonstration of acid fast bacilli. Chronic fibrosis of thyroid has been described in association with tuberculosis particularly by European authors although the exact relationship of sclerosing thyroiditis to tuberculosis remains in doubt.[1] Disorders of thyroid function have seldom been described in association with tuberculous thyroiditis. Mosiman (1917) recorded seven cases to be clinically thyrotoxic but no biochemical confirmation was possible.[12]
Seed (1939) described 3 prerequisitic conditions to be present for diagnosis of thyroid tuberculosis, these are: i) demonstration of Acid Fast bacilli within thyroid, ii) a necrotic or abscessed gland and iii) demonstration of tuberculous focus outside. Histological and bacteriological confirmation is adequate to make diagnosis and fulfillment of third criterion is not essential.[1] Diagnosis is most difficult when tuberculosis presents as a thyroid nodule only because such cases are unassociated with overt tuberculosis elsewhere.[7] That is why almost all reported cases of thyroid tuberculosis were based solely on histological findings,[2] as was seen in the reported case. Histological diagnosis is based on the presence of epithelial cell granulomas with peripheral cell lymphocytic cuffing, Langhans giant cells and central caseation necrosis.[2] In the reported case there were no signs and symptoms suggestive of tuberculosis anywhere in the body except raised ESR of 55 mm nor did the lump appear tubercular clinically. Histological demonstration of epithelial cell granulomas with peripheral lymphocytic cuffing, Langhans giant cell and central caseation necrosis proved the diagnosis of thyroid tuberculosis.
Surgery with administration of antituberculous drugs is considered to be the treatment of choice as was done successfully in the case reported.[2]
It is therefore important to note that-
— Tuberculosis should be considered in the differential diagnosis of anterior cervical swellings,
— FNAC can help in confirming the diagnosis,
— Final confirmation is made by histopathological and biochemical examination,
— Patients respond well to surgery with antituberculous drugs.
REFERENCES
1. Barnes P, Weatherstone R. Tuberculosis of the thyroid. Two case reports. Br J Dis Chest 1979; 73 : 187-91.
2. Kukreja HK, Sharma ML. Primary tuberculosis of the thyroid gland. Indian Journal of Surgery 1982; 44 : 190.
3. Mondal A, Patra DK. Efficacy of fine needle aspiration cytology in the diagnosis of tuberculosis of thyroid gland; a study of 18 cases. J Laryngol Otol Jan., 1995; 109 (1) : 36-8.
4. Hazard JB. Thyroiditis : A review. Am J Clin Path 1955; 25 : 189.
5. Coller FA, Huggins CB. Tuberculosis of the thyroid gland. Annals of Surgery 1926; 84 : 408.
6. Rankin FW, Graham AS. Tuberculosis of the thyroid gland. Ann Surg 1932; 96 : 625.
7. Goldfarb H, Schifrin D, Graig FA. Thyroiditis caused by tuberculous abscess of the thyroid gland. American Journal of Medicine 1965; 38 : 825.
8. Crompton GK, Cameron SJ. Tuberculosis of the thyroid gland mimicking carcinoma. Tubercle (London). 1969; 50 : 61.
9. Johnson AG, Phillips ME, Thomas RJS. Acute tuberculosis abscess of the thyroid gland. Br J Surg 1973; 60 : 608.
10. Karlish AJ, Macgregor GA. Sarcoidosis, Thyroiditis and Addison’s disease. Lancet 1970; 2 : 330.
11. Greene JN. Subacute thyroiditis. Am J Med 1971; 51 : 97.
12. Mosiman RE. Tuberculosis of the thyroid. Surg Gynec Obstet 1917; 24 : 680.
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