[Parathyroid carcinoma. Therapeutic strategies derived from 20 years of experience].

BACKGROUND: Carcinoma of the parathyroid is a rare endocrine tumour which can be difficult to diagnose even for expert anatomopathologists.
METHODS: A retrospective study was carried out on all the cases of parathyroid pathology observed between January 1980 and October 2000: parathyroid carcinoma was diagnosed in 17 (3.59%) out of 478 patients treated for hyperparathyroidism. We describe their clinical presentation, treatment and results obtained. The patients included 9 women and 8 men, with a male/female ratio of 1.14 and a mean age at diagnosis of 56.9 years (range 30-83). All the patients, except one, the only non-secreting case, presented hypercalcemia, and 10 patients presented serum calcium levels above 3 mmol/L. The symptoms at onset included: nephrolithiasis in 10 cases, osteoporosis in 4 (3 of which presented uremic syndromes), gastrointestinal symptoms (gastritis) in 1 case, a palpable cervical mass in 1 patient and recurrent nerve palsy in one case suffering from familial IPT. A variety of imaging techniques were used for the preoperative localisation: high-resolution ultrasonography of the neck was carried out in all 17 patients and was positive in 15 cases; scintigraphy (99mTcO4/201Tl or 99mO4/MIBI) was carried out in 16 patients and was positive in 14; CAT was positive in 6 out of 17 patients. Three patients underwent the first operation in another hospital and were referred to our department for resistance or recidive. Initial surgery was restricted to simple parathyroidectomy in 4 cases; parathyroidectomy was extended to the entire gland in 3 patients with uremic syndrome and to the ipsilateral thyroid lobe in 7 cases. Three patients underwent parathyroidectomy extended en bloc to the adjacent structures, and recurrent lymph node dissection was also performed in 2 of these patients. Lymph node involvement was never demonstrated during the first operation. The dimensions of the tumour varied from 1 to 6.7 cm; we found signs of invasion of the neighbouring structures in 3 patients.
RESULTS: Parathyroid carcinoma was correctly diagnosed during the first operation in 14 cases (this diagnosis was suspected in 10 cases following intraoperative frozen session), whereas the first diagnosis was of benign disease in 3 patients. Blood levels of calcium, phosphorus and PTH returned to normal after the first operation in 13 patients. These values diminished, but did not return to normal in 2 cases. Two patients relapsed, respectively 5 and 175 months after the first operation. A total of 10 reoperations were performed in 4 patients with persistent/recurrent symptoms (from a minimum of 1 to a maximum of 4). Recidive presented characteristics of local invasiveness in one case and the persistence was supported by micro-insemination of the pre-thyroid compartment and muscles in another two cases. At reoperation, lymph node metastasis was associated with local recidive only in one case. Two patients underwent radiotherapy after surgery and one received chemotherapy. At the last check-up (October 2000), 14 patients were alive and disease-free (82.25%). Two presented slight persistent hypercalcemia (with values ranging between 2.65 and 2.80 mmol/L), but without any macroscopic localisation of disease (11.76%). Only 1 patient died (5.88%) (one year after the first operation and 7 months after the last one). Death was caused by uncontrollable hypercalcemia supported by widespread metastasis to the bones and lungs. The 5 and 10-year survival rates were calculated as 94.12%.
CONCLUSIONS: In conclusion, high blood levels of calcium and PTH, a palpable mass at the neck, with recurrent nerve paralysis, aspects of local invasiveness should alert the surgeon and guide him towards surgery that includes resection of the parathyroid en bloc with the adjacent structures, although there is no proof that a more extensive surgery is correlated with a more favourable prognosis. Being the majority of recidive functional, monitoring serum calcium and PTH levels offers a useful market which precedes their macroscopic demonstration.