primary hyperparathyroidism is a disorder in which excess parathyroid hormone ( pth ) is secreted from one or more of the parathyroid glands . the inappropriately increased secretion of pth usually affects calcium and phosphate levels , and bone metabolism , resulting in hypercalcemia and hypophosphatemia . however , clinical manifestations of primary hyperparathyroidism are variable in terms of etiology and serum pth levels . approximately 70% to 80% of patients with primary hyperparathyroidism are asymptomatic ; these patients are often identified following screening of calcium levels during other investigations . the remaining 20% to 30% of patients often present with recurrent nephrolithiasis , osteoporosis , proximal muscle weakness , and psychiatric symptoms . a brown tumor is a focal , benign bony lesion caused by localized , rapid osteoclastic turnover of bone , resulting from direct effects of pth . brown tumors are one of the most pathognomonic signs of primary hyperparathyroidism ; however , they are rarely seen in clinical practice . brown tumors have been reported occur in 1.5% to 4.5% of patients with primary or secondary hyperparathyroidism . there have been reports of brown tumors associated with primary hyperparathyroidism , but most of them present a focal brown tumor usually localized to the jaw and maxilla . here , we report a case of extensive brown tumors and multiple fractures caused by a parathyroid adenoma in a 20-year - old woman . a 20-year - old mongolian woman was referred to our endocrinology department for further evaluation of recurrent fractures and bone tumors . she had been experiencing bone pain and recurrent bone fractures of the limb over 2 years following minor trauma . three months previously , she had undergone surgery of the left humerus in a mongolian tertiary care center . she was also evaluated for a tumorous lesion associated with the fracture site ( fig . the biopsy report of the tumorous lesion identified that it was composed of multiple giant cells and some fibroblasts suggestive of a brown tumor or giant - cell tumor . however , there had not been any further evaluations of the tumor or the fractures . at the first visit to our clinic , she complained of pain and tenderness of her left lower leg and left knee joint . plain digital radiographs of the affected bones ( both tibia and fibula , metatarsal bones , left proximal ulna and humerus , left distal ulnar and third metacarpal bone ) revealed multiple bony osteolytic expansile lesions with cortical thinning , diffuse osteoporosis , and subperiosteal bone resorption compatible with brown tumors ( fig . 2 ) . additionally , a radiograph of her skull showed a granular " salt and pepper " appearance , typical finding of primary hyperparathyroidism ( fig . 3 ) . initial laboratory tests indicated elevated serum calcium levels of 10.3 mg / dl ( normal range , 8.8 to 10.0 ) , ionized calcium levels of 6.01 mg / dl ( normal range , 4.4 to 4.9 ) , and low phosphorus levels of 1.3 mg / dl ( normal range , 2.5 to 4.5 ) . serum alkaline phosphatase levels were elevated at 2,032 iu / l ( normal range , 30 to 120 ) , and serum intact pth levels were markedly increased to 978.4 pg / ml ( normal range , 8 to 76 ) . twenty - four - hour urinary calcium was also elevated at 555.4 mg / day ( normal range , 100 to 300 ) . further laboratory tests including serum pth - related peptide , albumin , and creatinine were within normal limits . a parathyroid imaging work - up with neck ultrasonography and a parathyroid scan ( technetium-99 m sestamibi ) revealed an approximately 2 cm mass in the inferior aspect of the left thyroid gland , suggestive of a solitary parathyroid adenoma ( figs . 4 , 5 ) . dual - energy x - ray absorptiometry identified osteoporosis ; the z - score for the left femur neck was -5.5 ( 0.21 g / cm as bone mineral density [ bmd ] ) , and for the spine was -3.6 ( 0.59 g / cm as bmd ) . further tests for multiple endocrine neoplasm type 1 , including pituitary hormones , revealed no additional abnormal findings . following management of bone pain and fracture sites , a left - side parathyroidectomy was performed . a 2.62.12.1 cm , multi - lobulated , grayish - brown , soft mass was excised . 6 ) ; the lesion was distinguishable from the rim of compressed normal gland that contains abundant stromal fat . within the adenoma , tumor cells were arranged in cords and solid sheets , and mainly composed of chief cells , which have centrally placed hyperchromatic nuclei and pale eosinophilic cytoplasm . two days postoperatively , the patient experienced transient hypocalcemia ( 7.3 mg / dl ) , but recovered with calcium carbonate supplementation . four days postoperately , serum intact pth level was decreased to 17.3 pg / ml . three days afterwards , she was discharged free of symptoms , and returned to mongolia . primary hyperparathyroidism is a disorder in which excess pth is secreted from one or more of the parathyroid glands . the prevalent routine serum chemistry screening of calcium brought early detection of primary hyperparathyroidism , which led to a decrease in classical form with renal stones or bone manifestations . the incidence of primary hyperparathyroidism is reported as approximately 22 per 100,000 persons per year . primary hyperparathyroidism is more common in woman than man , and peak incidence occurs in the 6th to 7th decade of life . . a brown tumor is a bone lesion that results from bony resorption by excess osteoclastic activity , and replacement by fibrous tissue and giant cells . most of the reports presented a solitary lesion , generally localized to the facial bones , and more frequently associated with secondary hyperparathyroidism than primary hyperparathyroidism . our case is unique in several aspects ; the patient presented with multiple , extensive brown tumors , mainly involving bones of the limbs , and related fractures . several reports have presented cases of multiple brown tumors associated with primary hyperparathyroidism . however , in those reports , the tumors usually affected the maxilla , pelvis , and ribs , other than long bones . there have been also similar reports with multiple brown tumors involved in bones of limbs in korea , the young woman in our case experienced recurrent fractures , which has not been observed in other cases , implying a clinically overt form of brown tumors . another notable finding from our case is that the patient was a 20-year - old woman . considering that the first occurrence of fracture was approximately 2 years prior to diagnosis , we assume that hyperparathyroidism was present for a considerable length of time before that first fracture . we only identified one other case of an adolescent female with multiple brown tumors in turkey . because the presentation of our case was atypically severe , and developed in a young woman , we could have considered another possible diagnosis , including giant - cell tumor , or metastatic bone lesions . the main differential diagnosis was giant - cell tumor , which is a highly vascular lesion usually found in the metaphysis or epiphysis of a limb bone , in the pelvis , or in the spine . a large case series of 195 patients showed that the peak incidence of giant - cell tumor was in the third decade of life , and usually involved the distal part of major tubular bones in the extremities , a description which resembles our case . the radiological appearance and histology of giant - cell tumors may closely mimic those of brown tumors ; therefore , the clinical manifestation and laboratory tests play an important role in the differential diagnosis . in this case , a biochemical assay and subsequent parathyroid imaging definitively confirmed a diagnosis of primary hyperparathyroidism ; therefore , we could follow the standard treatment protocol without confusion . the patient had to return to mongolia following treatment ; therefore , we could not perform our usual clinical follow - up after the parathyroidectomy . most of the previous reports showed slow regression of bone lesions and improvement of bmd following the operations . in summary , we have presented a case of a young woman with multiple brown tumors and related fractures associated with primary hyperparathyroidism . although very rare , this case showed that multiple , and clinically severe , brown tumors can even occur in young patients .
a brown tumor is a benign fibrotic , erosive bony lesion caused by localized , rapid osteoclastic turnover , resulting from hyperparathyroidism . 
 although brown tumors are one of the most pathognomonic signs of primary hyperparathyroidism , they are rarely seen in clinical practice . in this report , we present a case of 20-year - old woman with recurrent fractures and bone pain . 
 plain digital radiographs of the affected bones revealed multiple erosive bone tumors , which were finally diagnosed as brown tumors associated with primary hyperparathyroidism due to a parathyroid adenoma . 
 this case shows that multiple , and clinically severe form of brown tumors can even occur in young patients .