Coexisting parathyroid adenoma, thyroid carcinoma, and tuberculosis of thyroid: a case report

Background: Coexisting parathyroid adenoma, thyroid carcinoma, and tuberculosis of thyroid is a very rare phenomenon. Primary thyroid tuberculosis is itself very rare despite high global prevalence of tuberculosis in developing countries. Majority of thyroid tuberculosis identified in postoperative histopathology or cytopathology. The coexistence of thyroid cancer with tuberculosis or parathyroid adenoma has been reported in the literature but not a single case of the three pathologies coexisting together has been found in the literature published. We are presenting a rare case of a constellation of synchronous parathyroid adenoma, thyroid carcinoma, and thyroid tuberculosis. This case report will provoke researchers to work on understanding the association of hypercalcemia or chronic inflammation leading to development of malignancy or parathyroid adenoma in the presence of hypothyroidism will give future perspective in managing such patients.

Case presentation: A Islam lady aged 45 years old, diagnosed with hypothyroidism, was evaluated for pregnancy loss and rapid weight gain from 13 years back and started on tablets of levothyroxine 25 µg once daily. She was doing well until the past 2 years; there after she noticed insidious onset of a swelling over anterior aspect of right side of the neck and bone pain in back and lower limbs. Patient underwent routine investigations and was found to have raised serum calcium (11.4 mg/dl) and parathyroid hormone (253 pg/ml). Anti-thyroid peroxidase (TPO) and anti-thyroglobulin (Tg) level were normal. Ultrasounds showed multiple nodules in both lobe of thyroid and left inferior parathyroid adenoma. The patient underwent total thyroidectomy with left inferior parathyroidectomy, and final histopathology showed features of subacute granulomatous thyroiditis along with hurthle cell change in right lobe of thyroid. The left lobe additionally showed necrotizing epitheloid cell granulomas, which on Zeihl-Neelson staining revealed presence of acid-fast bacilli. Sections from the isthmus show a focus of papillary thyroid microcarcinoma. The left inferior parathyroid gland sent as a frozen sample was found to be parathyroid adenoma. On 6-month follow-up, the patient was feeling much relief in bone pain and tolerating antitubercular drugs uneventfully.

Conclusion: Coexistence of parathyroid adenoma, nonmedullary thyroid carcinoma, and thyroid tuberculosis is extremely rare. Surgery is curative for hyper parathyroidism and thyroid carcinoma. Thyroid tuberculosis responds well to current antitubercular drugs. Its etiology needs to be explored more; the probable hypothesis is chronic inflammation due to latent tuberculosis might leads to development of thyroid carcinoma and parathyroid adenoma. Further studies need to be done for better understanding of underlying mechanism and better management options for such patients. To the best of our knowledge, similar cases have not been reported.