Endocrine Abstracts

Introduction: Parathyroid carcinoma (PC) accounts for <1% of all forms of primary hyperparathyroidism. PC is characterized by very high serum PTH and calcium levels and presents with osteopenia/osteoporosis, nephrolithiasis, asthenia, neuropsychiatric symptoms. Here, we report the unusual presentation of a PC.

Case presentation: A 48-year-old woman was referred to our Center for the sudden appearance of a large painful hematoma in the cervico-mediastinal area. Neck US showed a solid, markedly hypoechoic lesion (40×80×55 mm), extending from the right thyroid lobe to the mediastinum, associated to blood leakage in the right perithyroid area. The thyroid displayed a diffusely hypoechoic structure, without nodules. Lab tests showed: TSH 2.1 mIU/ml, Calcitonin <1 pg/ml, PTH 460 pg/ml, Calcium 14 mg/dl, Calcium ion 2.1 mmol/l, Calciuria 535 mg/24 h, Phosphorus 2.5 mg/dl, Creatinine 0.65 mg/dl, 25-OH vitamin D 10 ng/ml, CEA 2 ng/ml. Femoral-lumbar DXA detected osteopenia and renal US showed a stone within the left kidney. Neck CT demonstrated a huge mass extending from the right thyroid lobe up to the right upper bronchus and displacing the esophagus and the trachea controlaterally.

Treatment: The patient was rehydrated, treated with furosemide, cholecalciferol and bisphosphonate and submitted to right lower parathyroidectomy + right hemithyroidectomy + lymphadenectomy of the right VI cervical level. Histological examination was diagnostic for non-angio-nor neuro-invasive PC associated to lymphocytic thyroiditis; all removed lymph nodes were benign.

Outcome and follow-up: The post-operative course was regular. The patient was discharged with calcitriol and calcium carbonate therapy, then suspended. The search for mutation of the CDC73 gene was negative. The 30-day follow-up included blood tests showing normal PTH and calcium concentrations and subclinical hypothyroidism with TSH elevated at 18 mcIU/ml Neck US did not detect residual neoplasm and 99mTc-MIBI parathyroid scan was negative. Levothyroxine therapy 50 μg/day was undertaken. Eight years after diagnosis, the patient is in good general condition, with no clinical, biochemical or imaging evidence of disease persistence/recurrence.

Conclusions: We have described the unique case of a PC presenting with pain and hematoma in either the anterior neck and the mediastinum, associated with autoimmune thyroiditis. Although parathyroid hemorrhage is a rare event, it should always be suspected when a painful swelling suddenly appears in the neck region in a hypercalcemic patient. Given the high prevalence of HT in the general population, we believe that the association between PC and autoimmune thyroiditis in our patient should be considered casual.