Endocrine Abstracts

Introduction: Brown tumors are rare, destructive, osteolytic bone lesions, occurring in advanced stages of hyperparathyroidism, due to increased osteoclastic activity.

Case report: A 25-year-old woman presented with recent, intractable pain on the right shoulder and with hypercalcemia (Ca, 3.93 mmol/l) related to severe primary hyperparathyroidism (PTH, 494 pg/ml). Multiple osteolytic lesions, detected on the upper extremity of the right humerus, distal right radius, sternal end of the right clavicle, right acromion and bilateral sacroiliac joints were depicted having intense uptake on Tc-99m tetrafosmin scan. Tc-99m-HDP whole body bone scan coupled with low dose CT, realized 24 h later, revealed decreased uptake in the humeral head tumor, associated with large areas of osteolysis lined by thinned and expanded cortical borders, while all other osteolytic bone lesions still presented increased uptake. Both CT and MRI identified the localization of these benign tumors, while the pathology assessment of the humerus tumor confirmed the diagnosis. Left superior parathyroid adenoma was detected by parathyroid scintigraphy and surgically removed, with consequent improvement in bone pain and calcification of the lytic lesions. However, the large humeral brown tumor was still responsible for functional impotence two months after parathyroidectomy, thus necessitating orthopedic assessment for arthroplasty.

Conclusion: Large brown tumors exhibiting intense Tc-99m-tetrafosmin uptake while lacking Tc-99m-HDP uptake are active tumors with an important lytic component, necessitating complex investigations and follow-up. Our case emphasizes the necessity of a multimodality imagistic approach to optimize the assessment of the severity and the extent of brown tumors, allowing multidisciplinary specific therapeutic options.