ODP121 Recurrent atypical parathyroid adenoma: a case report

BACKGROUND: Atypical parathyroid adenoma is a rare cause of hyperparathyroidism, with an incidence ranging from 0.5 to 4.4%. Its recurrence rate is low, around 3%. We describe a young patient with an atypical parathyroid adenoma that recurred twice at the right neck. CASE PRESENTATION: A 39-year-old woman presented to the ER with low back pain, hyporexia, weight loss, and an oral lesion with purulent discharge. She was diagnosed with nephrolithiasis, severe hypercalcemia (serum calcium concentration: 21,2 mg/dl (Reference range 8,5-10,5) and hyperparathyroidism (serum PTH: 703 pg/mL; reference range 15-45pg/mL). Parathyroid scintigraphy identified an uptake at the site of the lower right parathyroid. A cervical US confirmed the presence of a 3 cm markedly hypoechoic nodule in that location. Fine needle aspiration (FNA) suggested parathyroid adenoma, and PTH washout levels were 1900 pg/ml. Screening for multiple endocrine neoplasia was negative. Biopsy of the mandibular alveolar bone, around the oral lesion, showed giant cell lesion. Lower right parathyroidectomy was performed, and the histopathology showed parathyroid neoplasm with features favoring atypical parathyroid adenoma (lesion measuring 3×2×1.8 cm). Fifteen months after the surgery, the patient presented symptoms of hypercalcemia, with a new elevation of serum PTH levels (738 pg/ml), confirmed with radiotracer uptake at the site of the upper right parathyroid gland. She underwent right parathyroidectomy and hemithyroidectomy. Histopathology revealed an atypical parathyroid adenoma. Immunohistochemistry was positive to galectin 3 in rare cells; Ki 67 positive (2%). After nine months, the patient noticed a subcutaneous nodule in the right anterior cervical region associated with symptomatic hypercalcemia, and a new increase in serum PTH levels (469.5 pg/mL). Parathyroid scintigraphy confirmed radiotracer activity at the nodule described, that was surgically resected. Histopathology was compatible with an atypical parathyroid neoplasm (uncertain malignant potential). The patient remains in regular follow-up, asymptomatic and normocalcemic. CONCLUSION: While 96% of patients with atypical parathyroid adenomas are cured with parathyroidectomy, this case shows a very rare description of two recurrences in a short time of follow-up, with an ectopic location in the last one. It should be noted that atypical paratyroid adenomas are already an uncommon presentation of primary hyperparathyroidism. Genetic investigation is warranted in such cases. Presentation: No date and time listed