Tuberculosis of the thyroid gland is an uncommon disease and primary involvement of thyroid is even more rare. It is a rare disease even in countries in which tuberculosis is endemic. The diagnosis is often difficult as the clinical presentation has no distinct characteristics. Clinical course of the disease may resemble toxic goiter or acute thyroiditis or may follow a subacute or chronic growth pattern without specific symptomatology. Histologically presence of necrotizing epithelioid cell granulomas along with langhans type giant cells are the hallmark of thyroid tuberculosis. Demonstration of acid fast bacilli by ZN staining confirms the diagnosis, but this stain is frequently negative in tissue sections.

Thyroid gland is rarely affected by tuberculosis. It was once considered immune from the disease till Lebert in 1862 reported the involvement of the gland in a patient with disseminated tuberculosis. Tuberculosis of thyroid is rare even in countries with high prevalence of tuberculosis. There have been isolated case reports and few case series of thyroid tuberculosis in the literature. The supposed reasons for the relative immunity of thyroid gland from tuberculosis are the bactericidal attribute of the colloid, extensive vascularity and high iodine content of the gland the primary form of the disease is even rarer. Most of the cases are accompanied by other loci of the disease in the body. Sometimes associated with regional lymph nodes, thyroid tuberculosis can mask a thyroid tumor, which poses diagnostic and therapeutic issues.. Thyroid involvement can be symptom free as seen in generalized miliary spread, diffuse or localized swelling of the gland. It can also present as thyroid abcess in pulmonary tuberculosis patients. We present a case of a 35 years old female who presented with painless solitary thyroid nodule for one year, which on histology was proved to be tuberculosis of thyroid.