Ectopic parathyroid adenoma with severe osteoporosis in premenopausal woman

INTRODUCTION: Primary hyperparathyroidism (PHPT) is defined as unsuppressed secretion of parathyroid hormone leading to a dysregulated bone and mineral metabolism and ultimately causing hypercalcemia. The main reasons for its development are parathyroid adenomas (PAs) with an estimated prevalence of 1–4/1.000 in the general population, predominant in postmenopausal women. Ectopic location of the parathyroid glad occurs in 6–16%.1 The most common location of ectopia is thymus, the next retroesophageal region and thyroid gland. We present a case of ectopic thymic parathyroid adenoma with severe clinical manifestations. CLINICAL CASE: A 43 years old woman patient applied to the clinic with complaint of bone pain, especially at the waist and hip. She had also difficulty in walking. Her laboratory tests were as follows; Ca: 9.65 mg/dl, albumin:45 g/dl, corrected Ca:9.25 mg/dl, phosphorus: 0.55 mmol/l (0.81–1.45), thyroid stimulating hormone (Tsh) 5.8 miu/l,Alp: 369 u/l, Pth: 442 pg/ml, vitamin D: 13 ng/mL, Mg:0.84 mmol/l. In radiologic findings; Hip and knee MRI revealed T1 hypointense, STIR and T2 hyperintense cystic lesion on the iliac wing of the left sacroiliac joint 36×13 mm in size, intraosseous cystic lesion on the right knee cap 16×26×27 mm in size. And cystic lesion was observed in the diaphysis region of the upper 1/3 of the right tibia 8×7×22 mm in size. The patient was found to be osteoporotic on dual energy X-ray absorptiometry (DEXA) scanning (Z score =−6.3 at the lumbar spine; Z score =-6.4 at the femur neck and Z score =-5.8 at the total femur). Neck ultrasound revealed an incidental thyroid nodule but no lesion suggestive of parathyroid adenoma was observed in ultrasonography. Vitamin D replacement therapy was started. After 4 weeks, laboratory tests were as follows; vitamin D:21 ng/ml, Pth:364 pg/ml, Ca: 10.65 mg/dl, albumin: 3.8 g/dl corrected Ca: 10.81, phosphorus: 0.73 mmol/l Alp:392 u/l, renal function tests were in the normal range. And 24-hour urinary calcium was 652 mg/day, fractional excretion of calcium (FeCa): 0.023. 24-hour urinary phosphorus: 29 mmol/day (normal). The patient was started on bisphosphonate therapy. Parathyroid sintigraphy was taken for localization purposes in the patient with hyperparathyroidism. In the early and late imaging of the anterior mediastinum, MIBI collection was detected behind the manubrium sterni with a size of 15×10 mm consistent with a parathyroid adenoma. The patient was consulted with thoracic surgery and the operation was performed. In the post-examination assays, Ca: 8.64 albumin: 3.8 g/dl corrected Ca: 8.75 mg/dl phosphorus: 2.54 mg/dl Pth: 41 pg/ml. Pathology resulted as ectopic thymic parathyroid adenoma. CONCLUSION: Although ectopic parathyroid adenoma is not common in premenopausal women, it should be considered as a cause of severe osteoporosis.