Endocrine Abstracts

Background: Overt parathyroid bone disease is a rare entity. We present a case of primary hyperparathyroidism (PHPT) and osteitis fibrosa cystica with involvement of multiple facial bones and neurocranium. Although the initial differential diagnosis was between acromegaly and bone malignancy, endocrine assessment demonstrated PHPT, with favorable outcome after parathyroidectomy.

Case report: A 59-year-old woman referred to our clinic with painful swelling of frontal and maxillary bones. A computed tomography (CT) of the skull performed before admission raised the suspicion of osteosarcoma which was invalidated by bone biopsy. The patient had no history of fractures and her family history was not significant. Although facial changes indicated acromegaly, biochemical evaluation showed normal IGF1 (169.3 ng/ml) with normal GH nadir (0.06 ng/ml) during OGTT and revealed high corrected serum calcium (12.06 mg/dl, n=8.5–10.2), low serum phosphorus (2.05 mg/dl, n=2.5–4.5) and high PTH level (384.2 pg/ml, n=15–65), demonstrating PHPT; the bone turnover markers were elevated: crosslaps=0.89 ng/ml (n=0.33–0.78), osteocalcin=53.77 ng/ml (n=15–46), P1NP=89.16 ng/ml (n=15–74); alkaline phosphatase was 112 IU/L (n=38–105) and serum 25OHD was 9.61 ng/ml (n=30–100). 24 h urinary calcium was 760 mg/24h (n=70–300) and 24 h urinary phosphorus was 1080 mg/24 h (n=300–1000). Calcitonin, plasma metanephrines and normetanephrines, PRL and Chromogranin A were in normal range. Abdominal ultrasonography revealed unilateral nephrolithiasis and renal function was normal (GFR=107.7 mL/min/1.73 m²). We reevaluated the CT scan of the skull that showed expansive lytic and sclerotic mass lesions at the level of frontal sinuses, ethmoid cells and within the maxillary sinuses, together with ‘salt and pepper’ appearance of the skull. A neck CT-scan and 99 mTc sestamibi scintigraphy of the parathyroid glands showed a parathyroid adenoma. The patient underwent surgery and a right lower parathyroid adenoma was removed. The anatomopathological report described a chief cells parathyroid adenoma weighing 2.46 g. On a six months follow-up, under cholecalciferol treatment (2000 UI/day), DXA showed osteopenia with a T score of −1.6 DS for the lumbar spine and −1.1 DS for the distal radius and the patient had normal values of serum calcium (9.9 mg/dl), phosphorus (3.1 mg/dl) and PTH (57.46 pg/ml).

Conclusion: Even if osteitis fibrosa cystica is rare, when large lytic lesions are associated with hypercalcemia, PTH assay should be mandatory since PHPT must be always considered.