Brown Tumour; Solve The Puzzle and "Go to The Top of The Clasts'!" - A Case Presentation
48 y/o male presented with pain behind the patella of the left knee. X-Ray demonstrated a lytic lesion in the left lateral tibial condyle, potential diagnosis ranging from possibilities including multiple myeloma to metastatic disease. A Bone Scan was requested and showed the presence of multiple bony lesions.
CT was performed and demonstrated the multiple bony lesions as well as two soft tissue lesions; one in right thyroid and one in the left kidney both being possible primary malignancies. CT guided biopsy of left ileum lesion concluded a diagnosis of bony lysis secondary to hyperparathyroidism i.e. Brown Tumour.
Brown tumours or osteoclastomas are benign erosive bony lesions caused by increased osteoclastic activity; their high hemosiderin content gives a distinctive brown colour and hence their name. These lesions arise in 6% of patients with primary or secondary hyperparathyroidism. Typically brown tumours’ appear after a final diagnosis of hyperparathyroidism however, in this case the brown tumour was the first clinical sign.
On further investigation the patients parathyroid hormone levels were 20 times the upper normal limit a thyroid ultrasound confirmed the presence of a parathyroid adenoma. A sestamibi parathyroid scan demonstrated a lesion consistent with the presence of a parathyroid secreting tumour. Surgical removal of the adenoma and subsequent histopathology identified parathyroid carcinoma.
This case demonstrates the importance of piecing together the functional and anatomical information acquired by nuclear medicine, radiography and pathology to solve the puzzle. By working together we can all “go to the top of the clasts’”!