Brown Tumors Secondary to Tertiary Hyperparathyroidism Masquerading as Lytic or Sclerotic Skeletal Metastases on Preoperative/Postoperative 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: A Case Report

A Rare Manifestation of Secondary Hyperparathyroidism Due to Brown Tumors: A Case Report

Purpose

Brown tumors, also known as cystic fibrosa, are rare, benign, osteolytic, fibrotic lesions of the bones that occur secondary to hyperparathyroidism. They are caused by increased osteoclastic activity leading to an abnormal bone metabolism.

Case Description

Here, we present the case of a 58-year-old male, who presented with painful bony lesions, initially attributed to metastatic disease. After biochemical workout, imaging and biopsy, the nature of the lesions was revealed. We discuss the differential diagnosis and clinical management of the disease.

Conclusion

Patients with brown tumors should be assessed in the differential diagnosis of bony lesions and should always be tested for hyperparathyroidism. An early diagnosis is crucial for the successful treatment of such patients.

The value of integration of bone scan and targeted SPECT/CT in diagnosis of primary hyperparathyroidism with multiple bone brown tumor

Although parathyroid bone disease is rarely seen nowadays, skeletal manifestation can be the first sign of hyperparathyroidism (HPT) in some clinical practice. Nevertheless, the diagnosis of HPT is often overlooked. We describe three cases of multiple brown tumors (BT) in which bone pain and destruction were the first symptoms that masqueraded as a malignancy. However, according to the results of bone scan and targeted single-photon emission computed tomography/computed tomography (SPECT/CT), we considered BTs as the diagnosis in all of three cases. The final diagnoses were confirmed by laboratory tests and post-parathyroidectomy pathology. Parathyroid hormone (PTH) is significantly elevated in primary hyperparathyroidism (PHPT) as we know. However, such elevation is virtually never seen in malignancies. Diffuse or multiple foci of tracer uptakes in the bone scan were always seen in bone metastasis, multiple myeloma, and other bone neoplasm. When patients visited nuclear medicine for first consultation without biochemical results, radiological evidence from planar bone scan and targeted SPECT/CT can help in distinguishing the skeletal diseases. Lytic bone lesions with sclerosis, intra-focal or ectopic ossification and calcification, fluid-fluid level, and distribution of the lesions may be helpful in the differential diagnosis in these reported cases. In conclusion, when patients present with multiple foci of uptake on bone scan, targeted SPECT/CT is acquired for suspicious lesions, which can increase the diagnostic sensitivity and reduce unnecessary interventions and treatment. Moreover, BTs should be always kept in differential diagnosis of multiple lesions without a conclusive primary tumor.