Multiple osteolytic lesions are usually associated with metastatic involvement of the bone. However metabolic bone diseases should also take their place in differential diagnosis. Here, we describe a primary hyperparathyroidism case with full-blown osteolytic lesions wich was diagnosed at first sight with having metastatic bone involvement. PET CT scan and laboratory results excluded a metastatic bone malignancy. Elevated serum calcium of 13.16 mg/dl, decreased serum phoshorus of 1.4 mg/dl and high intact-PTH level of 1054.7 pg/ml pointed out primary hyperparathyroidism. Sonographic examination revealed two adenomas of 2.9 × 3.3 mmand 3.3 ×2.7 mmin the left superior and right inferior parathyroid glands, respectively. Scintigraphy confirmed the presence of adenoma on the left.
Primary hyperparathyroidism (PHPT) is usually unveiled during the search of hypercalcemia etiology. Parathyroid adenoma is the leading cause of PHPT [
A 55-year-old woman presented with early fatigability and persistant left hip and thigh pain. The X-rays taken at another hospital showed multiple osteolytic lesions in the left pelvic area and on bilateral femoral neck. She was referred to our institution with the diagnosis of metastatic bone malignancy.
The patient’s medical history was significant for bilateral nephrolithiasis and osteoporosis. The pain had a progressive characteristic, disturbing her during sleep. The physical examination did not reveal a significant pathology. Serial plain radiographies showed previosuly noted multiple osteolytic lesions (
bone malignancy was not of concern anymore. Search for a potential diagnosis of a metabolic bone disease revealed a high intact-PTH level of 1054.7 pg/ml. In order to unveil the cause of hyperparathyroidism sonographic examination was performed and it revealed two adenomas of 2.9 × 3.3 mm and 3.3 × 2.7 mm in the left superior and right inferior parathyroid glands, respectively. Scintigraphy confirmed the presence of adenoma on the left. Considering the last evidences, brown tumor caused by parathyroid adenoma was the most probable diagnosis.
During her follow-up at in-patient clinic, hypercalcemia of the patient did not improve with intravenous hydration and furosemide. Awaiting the surgical procedure intravenous zolendronic acid infusion was performed. Calcium levels decreased to 11.3 mg/dl before the operation. After excision of left parathyroid adenoma calcium and PTH levels further decreased until 9.1 mg/dl and 34 pg/ml, respectively.
Finding of multiple osteolytic lesions usually is thought to be hall mark of metastatic involvement. Therefore in case of osteolytic bone involvement a tumor survey should be accomplished. Medical history, physical examination, laboratory tests and imaging techniques are the key screening tools for diagnosis of a primary tumor [3-5].
However, metabolic bone diseases should also be taken into consideration. In our patient, presence of multiple osteolytic foci was consistent with metastasis but when medical history, biochemical and radiological analysis were evaluated all together, diagnosis of a malignity became less likely. History of urolithiasis and osteoporosis in conjunction with the marked hypercalcemia, hypophospatemia and high PTH levels were clues for a metabolic bone diasease. Findings of sonography and scintigraphy had hallmarks of a parathyroid pathology. In the light of these evidence, diagnosis of brown tumor in association with PHPT was more likely.
As a rare and benign cause of osteolytic bone involvement, brown tumor is usually due to PHPT caused by an adenoma. Brown tumor causes increment in osteolytic resorption. Generally it is associated with single bone involvement. Diagnosis is based on clinical, radiologic and biochemical findings. After diagnosis of primary hyperparathyrodism is confirmed by biochemical results, a neck sonography confirms the presence of a parathyroid etiology and parathyroid scintigraphy increases the sensitivity for demonstration of a parathyroid pathology [6-7].
After the diagnosis is confirmed, key treatment of brown tumor is surgical removal of parathyroid adenoma. As PTH levels normalize after parathyroid surgery, brown tumor is expected to improve in size or to completely resolve [8-11]. In addition, orthopedic intervention can be necessary in case of pathologic fracture or extensive cortical involvement.
This report emphasizes the value of accurate diagnosis in cases with osteolytic lesions. The possible diagnoses such as metastatic bone involvement, multiple myeloma and metabolic bone diseases such as hyperparathyroidism due to adenoma have completely different means of treatment including chemotherapy or surgical removal of adenoma. Herein we have reported a case which was, at first glance, very similar to metastatic bone involvement but after a careful examination, it was found to have rather a benign cause. So for avoiding unnecessary interventions brown tumor should be kept in mind for differential diagnosis of osteolytic bone lesions.
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