Nowadays, primary hyperparathyroidism usually presents with the only evidence of hypercalcemia (Mazzaglia PJ, Berber E, Kovach A et al. The changing presentation of hyperparathyroidism over 3 decades. Arch Surg 2008;143:260–66 ), while the occurrence of an overt skeletal disease at presentation is a rare condition. We report a case where the disease presented with two bone masses, highly suspicious for malignancy.
A 38-year-old woman presented to the ambulatory of rheumatology, complaining of low back pain radiating to the thighs. Objective examination revealed dolorability of right sacro-iliac joint and limited flexion-extension of the lumbosacral spine. She performed a Magnetic Resonance of the lumbosacral spine, which revealed the presence of two lesions, respectively on the left ilium and on the right supero-anterior margin of the iliac crest, compatible with malignancy (Figure 1). She was then admitted to the hospital for more accurate investigations. Laboratory analysis demonstrated hypercalcemia (calcium 3,79 mmol/L), elevated PTH levels (PTH 1719 ng/L) and renal failure (creatinine 1,72 mg/dL). Bone densitometry performed on the femur neck showed a T-score of -2,8 DS.
Ecography of the neck demonstrated the presence of an hypoechogenic nodule of 2 cm, posterior to the lower right pole of thyroid. A subsequent Tc-99 sestamibi scintigraphy was consistent with hyperplasia/adenoma of the right inferior parathyroid.
Diagnostic path was completed with a CT-guided biopsy of the left iliac mass, whose histologic examination showed a fibrous proliferation with osteoclastic giant cells, a picture compatible with brown tumour. The patient was submitted to lower right parathyroidectomy with intraoperative PTH monitoring (Figure 3). Histology concluded for parathyroid adenoma. One year later, the patient is asymptomatic, the pelvic lesions are decreasing (Figure 1) and calcium and PTH values returned to the normal range.
Primary hyperparathyroidism is the third most common endocrine disorder, with an estimated incidence of 22 per 100.000 person/year. The disease is more commonly observed in post-menopausal woman, but the incidence is similar in patients younger than 50 years of age (Marcocci C, Cetani F. Primary hyperparathyroidism. New Engl J Med 2011;365(25):2389-97 ). Since calcium assays are performed in clinical practice from 1970s, awareness of the disease is grown and patients are diagnosed before they can develop late complications, such as brown tumours. In fact, nowadays only 20% of patients are symptomatic at the diagnosis, with nephrolithiasis as the most common manifestation. The percentage of patients presenting with the evidence of osteoporosis is increasing (Fraser WD. Hyperparathyroidism. Lancet 2009;374:145-158 ), and more attention is now paid to the subtle expressions of hypercalcemia, such as cardiovascular and neurological ones. Brown tumours represent the extreme of this clinical spectrum and constitute a disabling condition that enters into differential diagnosis with other primary or secondary bone tumours. In our case, simple calcium and PTH assays ruled out these hypotheses and the histology result supported our finding. In our case surgical parathyroidectomy, with the consequent normalization of PTH and calcemia, leads to remission of the bone lesions, as shown in Figure 1.
A high-degree hypercalcemia, associated with a PTH level thrice than the normal, should raise suspicion of parathyroid carcinoma (Marcocci C, Cetani F, Rubin MR et al. Parathyroid carcinoma. J Bone Min Res 2008;23:1869-80  ). In our case, however, histology ruled out a malignant neoplasia. However in many cases surgery may not be successful for the possible presence of ectopic parathyroids or diffuse hyperplasia, and other pharmacologic treatments, such as HRT, bisphosphonates and calcimimetics, may be taken into account for the management of hypercalcemia.