Brown tumours are rare, non-neoplastic, osteolytic bone lesions that arise in the setting of prolonged hyperparathyroidism. The lesions represent a manifestation of longstanding abnormal bone metabolism driven by persistently high parathyroid hormone (PTH) levels, often requiring both medical and surgical management. Brown tumours can be solitary or multiple, found in any part of the skeleton and the appearance can mimic skeletal metastasis. We present the rare case of multifocal brown tumours secondary to tertiary hyperparathyroidism and discuss relevant diagnostic and therapeutic considerations.
A 69-year-old female patient with end stage kidney disease secondary to focal sclerosing glomerulonephritis, requiring regular hemodialysis, reported symptoms of lower back and right hip pain. She had postmenopausal osteoporosis and tertiary hyperparathyroidism which required a partial parathyroidectomy 10 years prior. An initial CT scan of the spine revealed widespread skeletal lesions, which were evaluated in favor of metastasis and she was referred to an oncologist. A subsequent whole body PET scan showed bony lytic lesions throughout the spine, pelvis, all ribs, scapulae, skull, femur, distal humeri and distal left ulna. With no primary neoplastic focus, the PET scan findings were highly suggestive of brown tumors secondary to tertiary hyperparathyroidism. This was confirmed with a left sacral bone biopsy. The results of her laboratory tests showed calcium 2.27mmol/L (ref: 2.10-2.60), phosphate 1.27 mmol/L (ref: 0.75-1.50) and parathyroid hormone (PTH) 209.7 (ref: 1.6-7.2). She was reviewed by her endocrinologist and commenced on more aggressive medical treatment for tertiary hyperparathyroidism with increased cinacalcet dosage and commencing bisphosphonates to prevent bone resorption. She was urgently referred to an endocrine surgeon for a complete parathyroidectomy.
We present an unusual case of multifocal brown tumours secondary to tertiary hyperparathyroidism. This case was initially suspected as widespread metastases and highlights the importance of a comprehensive diagnostic approach, particularly in patients with chronic kidney disease.