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thyroid gland is rarely affected by tuberculosis , even in countries where tuberculosis is common .
children constitute very small proportion of these cases and according to terzidis et al . and razmpa et al .
we present a case of 11-year - old female child of thyroid tuberculosis who presented with a solitary thyroid nodule for 2 months and was diagnosed on cytological examination .
the present case is about an 11 years female child presented with a history of swelling in the thyroid region for preceding 2 months . on physical examination ,
thyroid gland was enlarged measuring 4.0  2.5 cm , firm in consistency and moving with deglutition .
computed tomography ( ct ) scan neck showed large bilateral lobes of thyroid right measuring 21  13 mm and left 16  18 mm showing heterogeneous tissue density with evidence of necrosis , bilateral cervical lymphadenopathy .
x - ray chest revealed non - homogenous opacity in the lower zone of lung on the right side .
enlargement of hilar and mediastinal lymph nodes , right side minimal pleural effusion and pleural thickening were found on ct scan of the thoracic cavity .
ultrasound of the abdomen revealed enlarged lymph nodes in periportal , portal , peripancreatic para - aortic regions .
hemoglobin was 10% g and erythrocyte sedimentation rate was 40 mm in 1 h. peripheral smear of blood revealed microcytic hypochromic anemia .
t3 , t4 and thyroid stimulating hormone were within the normal limits and anti - thyroid peroxidase antibody was negative .
on fine - needle aspiration from the thyroid swelling , thick cheesy fluid was aspirated .
the fluid was centrifuged and smears of the sediment showed caseating necrosis , few epithelioid cell granulomas and occasional benign follicular epithelial cells [ figures 1 and 2 ] .
based on caseating necrosis , epithelioid cell granulomas and demonstration of afb , diagnosis of thyroid tuberculosis was made . with treatment with antitubercular drugs ,
benign follicular cells and background of caseating necrosis ( giemsa stain , 400 ) epithelioid cell granuloma with caseating necrotic background ( giemsa stain , 400 )
the estimation of prevalence of this condition is difficult . however , reported prevalence rate varied from 0.1% to 1% .
rarity of tuberculosis in thyroid has been attributed to bactericidal property of colloid , high vascularity and excess of iodine , enhanced activity of phagocytes in hyperthyroidism and possible antitubercular roles of thyroid hormone .
involvement of thyroid by tuberculosis can occur by hemetogenous and lymphatic routes or by direct extension from cervical lymphadenitis .
earlier the criteria described for diagnosis of thyroid tuberculosis were finding of afb within thyroid , a necrotic or abscessed gland and presence of tuberculous focus outside the thyroid .
since it is not always possible to demonstrate afb , recently it is stated that multiple coalesced and caseating epithelioid cell granulomas along with giant cells are considered to be diagnostic of thyroid tuberculosis . in our case ,
the diagnosis of tuberculosis of thyroid was confirmed by demonstration of tubercular bacili in the specimen .
other extra thyroid lesions were also found in the present case which is similar to findings noted in many previous reports . although pathological assessment of these extra thyroid tissues was not done in the present case to avoid invasive investigations
, however , regression of these lesions with anti - tubercular drugs lends evidence to the possible tuberculous etiology in these lesions as well .
one of the peculiarities of our case is that involvement of large number abdominal lymph nodes ( periportal , portal , peripancreatic para - aortic regions ) besides cervical , mediastinal lymph nodes and pulmonary lesion . to the best of our knowledge ,
no case of thyroid tuberculosis was reported in the past wherein such widespread extra thyroid involvement was observed .
usually the tubercular involvement of lymph nodes in such patients was limited to one or two lymph node regions with or without pulmonary tuberculosis .
khan et al . in their study have reported four cases of thyroid tuberculosis , among them one case had cervical and axillary lymphadenopathy , another case had tuberculosis of cervical lymph nodes and third one had pulmonary tuberculosis and remaining one case did not reveal any involvement of extra thyroid tissue . likewise in the case reported by oklah and al - kaisi concomitant pulmonary tuberculosis and tubercular mediastinal lymphadenitis was found and mondal and patra in a study of 18 cases of thyroid tuberculosis found three cases had associated tubercular cervical lymphadenitis and four cases had pulmonary tuberculosis .
other atypicality is the younger age of our case , only very few cases were reported in this age group in the past , the most of previously reported patients were adults with the median age around 40s and .
there are case reports that suggest the possibility of primary thyroid tuberculosis in which there is no known focus of tuberculosis outside thyroid and such condition is even more uncommon .
like in current case , thyroid function test is generally found to be normal in these patients , but cases of thyrotoxicosis and hypothyroidism have also been reported .
being a rare entity , tuberculosis as the cause of thyroid swelling is unlikely to be suspected clinically .
however , like in the present case , fine - needle aspiration has also been found to be diagnostic in cases of thyroid tuberculosis thus preventing the unnecessary surgery .
differential diagnosis of granulomatous inflammation in thyroid includes subacute thyroiditis , goitrous autoimmune thyroiditis , tuberculosis and sarcoidosis .
it may be concluded that in cases of thyroid swellings tubercular thyroiditis should be considered as one of the differential diagnosis .
thyroid tuberculosis is a rare disease even in countries where tuberculosis is endemic . 
 clinically tuberculosis is not often suspected in cases of thyroid nodule or swelling . 
 we report a case of 11 years female child who presented with a thyroid swelling . 
 fine - needle aspiration cytology revealed caseating epithelioid granulomas and acid fast bacilli . 
 patient improved with antitubercular drugs . 
 tuberculosis may be considered as differential diagnosis of thyroid swelling .