Local recurrence as a first sign of parathyroid malignancy! Need to redefine the criteria for diagnosis of parathyroid carcinoma
A 40-year-old lady presented 3 years back with recurrent fractures. There was history of pancreatitis and renal stones in the past. She was bed-ridden due to the fractures, muscle weakness, and severe fatigue. Biochemical evaluation revealed serum calcium 13.3 mg% (Range 8.4-10.5 mg%), serum phosphorus 1.8 mg% (2.5-4.2 mg%), S iPTH 1891 pg/ml (20-60 pg/ml), S alkaline phosphatase 4320 IU/L. USG neck revealed 2.38 × 1.6 5 × 1.58 cm well-defined hypoechoeic lesion in the region of the left inferior parathyroid gland, which was also clinically palpable. At surgery, grayish-white, firm, left inferior parathyroid tumor was identified. The gross intra-operative features led to a suspicion of parathyroid carcinoma, even though there was no local invasion or regional lymphadenopathy. Hence, left hemi thyroidectomy was also performed along with the tumor excision. Other 3 parathyroids were inspected and found to be normal in size, shape, and position. Intra-operative PTH demonstrated >80% drop in the iPTH after excision. The histopathology report was adenoma [Figure and ]. Immunohistochemistry for malignancy (Rb protein) was not performed. She was under follow-up every 6 months. Patient was having normal serum calcium and iPTH for 3 years after surgery; however, she later developed hypercalcemia. At the second admission, her serum calcium was 15.8 mg%, S iPTH 822 pg/ml. Ultrasound neck and MIBI scans revealed the local recurrence [Figure and ]. No distant uptake of MIBI was noticed, ruling out a distant metastasis. X-ray of the chest and USG abdomen also did not reveal any distant metastasis. Re-exploration revealed recurrence at the previous surgery site and hence, a wide local excision with the adjoining strap muscles was performed. The histopathology confirmed parathyroid carcinoma []. At a follow-up of 3 months, patient has normal calcium and iPTH levels.