brown tumors are non - neoplastic lesions caused by complications of hyperparathyroidism ( hpt ) . it arises from areas of intense bone resorption and fibroblastic tissue fills in this cavity . this lesion associated with high parathyroid hormone levels due to hpt result in elevated osteoclastic resorption of bone . a 59-year - old man presented with a 10-month history of progressively increasing swelling in the left maxillary sinus and associated pain . he also had signs and symptoms of chronic renal failure developing following long - standing pyelonephritis with urolithiasis . routine laboratory exams revealed the following : blood urea nitrogen 33 mg / dl , serum creatinine 7.8 mg / dl , serum calcium 11.7 mg / dl ( normal range : 8.6 - 10.2 mg / dl ) , alkaline phosphatase 304 iu / l ( normal range : 40 - 150 iu / l ) , and parathormone 1942 pg / ml ( normal range : 12 - 65 pg / ml ) . due to the high serum calcium level , the patient was diagnosed with tertiary hpt associated with long - standing chronic renal failure . maxillofacial computed tomography ( ct ) scan revealed a 38  46  68 mm , well - defined , lobular , expansile radiolucent mass in the left maxillary sinus extending through the left nasal cavity , floor of the orbit , left infratemporal fossa , and premaxillary soft tissue . the mass was slightly hyperdense with adjacent soft tissue on contrast - enhanced maxillofacial ct scan [ figure 1 ] . the differantial diagnosis of the lesion included benign and malignant tumors of jaw , odontogenic tumors , infectious diseases , metastasis , simple bone cyst , and brown tumor . 59-year - old man presented with a 10-month history of pain and swelling inthe left maxillary sinus diagnosed with brown tumor associated with tertiary parathyroidism . ( october 14 , 2010 ) axial maxillofacial computed tomography scan shows a lesion on the floor of the left maxillary sinus extending through the nasal cavity ( red arrows ) , infratemporal fossa ( blue arrows ) , pterygopalatine fossa ( green arrows ) , and premaxillary region ( yellow arrows ) . the incisional biopsy followed by histopathologic investigation of the excised mass revealed a lesion with regions of discrete bone resorption with osteoclast activity , fibroblasts with areas of hemorrahage , and multinucleated giant cells [ figure 2 ] . finally , together with the medical history , imaging and pathological findings , and laboratory results , our case was diagnosed as tertiary hpt with brown tumor of maxillary sinus . postoperatively , there was distinct improvement as shown in the blood profile with serum phosphate , calcium , and parathormone levels dropping to 5.2 mg / dl , 9.8 mg / dl , and 3 pg / ml , respectively . there have been no signs of enlargement or destruction of adjacent bone tissue during the 27-month follow - up period . ct scan ( in january , 2013 ) 27-months post - treatment showed thickened cortical bone of the tumor walls , decreased tumor size , and increased density of the lesion matrix [ figure 3 ] . 59-year - old man presented with a 10-month history of pain and swelling inthe left maxillary sinus diagnosed with brown tumor associated with tertiary parathyroidism . histopathologic slide shows multiple giant cells ( black arrow ) with spindle - shaped stromal cells , fibrous connective tissue ( red arrow ) proliferation , and areas of hemorrhage ( yellow arrow ) ( h and e ,  40 ) . 59-year - old man presented with a 10-month history of pain and swelling in the left maxillary sinus diagnosed with brown tumor associated with tertiary parathyroidism . ( january 30 , 2013 ) 27-month post - treatment ( a ) axial and ( b ) coronal maxillofacial computed tomography images reveal thickening of bone walls of the lesion with a reduction of the tumor volume ( arrow ) and increase in the density of the lesion . within the group of hpt three subtypes are recognized : primary , secondary , and tertiary . primary hpt occurs due to increased parathyroid hormone ( pth ) secretion caused by abnormality in one or more of the parathyroid glands . secondary hpt occurs due to compensatory hypersecretion of parathormone and this condition may cause a decrease in blood calcium level . in rare cases , longstanding secondary hpt leads to hyperplasia of one or more parathyroid glands , and the system for normal inhibition of pth secretion by calcium is ruined . hpt leads to cortical bone resorption , development of microfracture , and subsequent bleeding in bone tissue . after this stage , multinucleated macrophage migrate to this area and the ingrowth of granulation tissue occurs . this lesion is known as brown tumor . brown tumor is a member of bone - expanding giant cell lesions , these lesions are giant cell reparative granuloma , cherubism , and brown tumor . histologically , brown tumor is composed of numerous multinucleated giant cells , dense fibroblasts and fibrous tissue , oseoid , hemosiderin deposits within macrophages , small microhemorrhages , and area of cystic degeneration of necrosis . the presence of chronic renal failure findings is a guide for the diagnosis of brown tumor in cases with secondary or tertiary hpt . the osseous lesion resulting from hpt is brown tumor and is found in approximately 10% of cases . these lesions can cause destruction to adjacent structures and lead to symptoms related to compression of surrounding organs . usually , this lesion orginates from the pelvis , ribs , clavicles , mandible , and extremities ; however , brown tumors can be detected in any osseous structure , including chondral tissue . in the head and neck region , this lesion is related with a high incidence of fractures if located in weight - bearing bones . symptoms of brown tumors of the sinonasal tract include epistaxis , facial swelling , pain , and bulging of the adjacent tissues . the most useful imaging studies for evaluation of brown tumor are ct and magnetic resonance imaging ( mri ) . on multislice ct , the most common manifestation of brown tumor is expansive and radiolucent bone lesion . ct may also show erosion of adjacent bone tissue . on mri , brown tumor shows expansile behavior with low to iso- signal intensity on the t1- and t2-weighted images . ct is the first - step imaging modality in defining and evaluating effect of maxillofacial brown tumors , while mri is the problem solving imaging modality . the differential diagnosis of an expansive and erosive maxillary sinus mass includes paranasal sinus malignancies , odontogenic tumors , metastatic carcinoma , fibrous dysplasia , giant cell reparative granuloma , aneurismal bone cysts , cherubism , or plasma cell tumor . when a tumor of the maxillary sinus has been diagnosed as a giant cell tumor , hpt should be ruled out to exclude the possibility that it is a brown tumor . surgical resection of brown tumor is usually not necessary , because dimensional regression and increased mineralization may take place once the pth level of blood is corrected . radiological differential diagnosis between a brown tumor and other histological giant cell tumors is not simple . craniofacial fibrous dysplasia generally invades the bones of the face or the skull base , and is observed most commonly in young women . reparative granulomas often arise in the alveolar arch of mandible or maxilla and affect children and young adults , generally females . . a reparative granuloma can be similar histologically and radiologically in appearance with a brown tumor . the presence of hpt and hypercalcemia may be useful to differentiate these granulomas from brown tumors . in the craniofacial region , aneurismal bone cyst is found more frequently in the mandible contains multiple septations and fluid - fluid level within the lesion . cherubism is a rare benign and familial disease of early childhood that is limited to the mandible and the maxilla . paranasal sinus malignancies , odontogenic tumors , metastatic carcinoma , and plasma cell tumor have nonspecific radiological findings and generally occur in adulthood with equal frequency among males and females . normalization of the pth level is essential and can be done with medications or by parathyroidectomy . in patients with a brown tumor in primary hpt calcium carbonate , vitamin d , aluminium hydroxide antacids , lantum carbonate , sevelamer , and calcimimetics can be used for medical treatment . clinical studies on calcimimetics have shown that these drugs ensures the increased calcium receptor sensitivity , causing a rapid decrease in pth levels . parathyroidectomy should be the first choice of treatment in tertiary hpt when the disease is refractory to medical therapy . although rare , the possibility of brown tumor should be kept in mind when assessing well - defined expansile maxillary sinus lesions .
brown tumor is a non - neoplastic bone lesion that develops secondary to hyperparathyroidism and it is very rare in the maxillofacial region . 
 we report the case of a 59-year - old man who presented with pain and a swelling in the left cheek . 
 computed tomography ( ct ) demonstrated an expansile and radioluscent lesion in the left maxillary sinus . 
 incisional biopsy was performed , and the diagnosis was brown tumor . 
 brown tumor must be considered in the differential diagnosis of expansile lesions of maxillary sinus .