A 60 year old woman had a history of fatigue and nephrolithiasis. Her serum calcium and parathyroid hormone levels were 11.45mg/dL (8.6-10.2) and 464,7pg/mL (15-65) respectively. Her tubular phosphate reabsorption rate was 56% while her chloride/phosphate ratio was 69,9. Her neck USG was normal. A parathyroid scintigraphy revealed a mass extending from lower pole of the left thyroid lobe to the mediastinal region with tracer retention. CT scan of neck and thorax verified the mass below the aortic arch, which was nodular, isodense with the thyroid gland and measured approximately 26x27 mm and detected another hypodense nodule within this bigger nodular mass measuring 13x11mm.