Atypical parathyroid adenoma: Severe manifestations in an adolescent girl.

Introduction: Primary hyperparathyroidism (PHPT) is a disease that is usually diagnosed in an asymptomatic state during routine biochemical screening. It generally manifests as a sporadic disease in post-menopausal women. However, in India and developing countries, we continue to see severe skeletal and renal manifestations of the disease.

Case report: Herein, we describe the case of a 16-year-old adolescent girl who presented with severe manifestations of primary hyperparathyroidism. Biochemically, she had severe parathyroid hormone (PTH)-dependent hypercalcaemia with hypophosphataemia and vitamin D deficiency (serum total Ca - 18.5 mg/dl [8.5-10.5 mg/dl], serum PO4 - 1.9 mg/dl [2.5-4.5 mg/dl], serum ALP - 2015 IU/l [80-240 IU/l], serum 25[OH]D - 19.1 ng/ml [30-100 ng/ml] and serum iPTH > 5000 pg/ml [15-65 pg/ml]). Pre-operatively, she required management with saline diuresis, bisphosphonate, and calcitonin. After surgery, the patient had severe hungry bone syndrome (serum Ca - 4.1 mg/dl, serum PO4 - 2.1 mg/dl, serum ALP > 10,000 IU/l) that required treatment with calcium infusions for almost 3 months. Although the clinical and biochemical picture was suggestive of parathyroid carcinoma, histopathology revealed atypical parathyroid adenoma with low proliferative index. Atypical parathyroid adenoma is a term applied to a neoplasm with 'worrisome' features but not fulfilling the 'absolute histopathological criteria of malignancy'.

Conclusions: Atypical parathyroid adenoma, a rare cause of PHPT, may be associated with severe manifestations. Although malignancy was not discerned in the immediate post-operative period, we plan to continue long-term follow-up of the patient to look for any signs of recurrence or development of parathyroid carcinoma.