follicular carcinoma of thyroid gland is the second most common thyroid cancer after papillary thyroid carcinoma . clinically , differentiated thyroid cancer ( dtc ) commonly presents with a solitary thyroid nodule and/or cervical lymphadenopathy . distant metastasis at initial presentation , especially those involving bone , is seldom seen and associated with poor clinical outcomes . in those cases , the axial skeleton and in particular the spine and the ribs are preferentially involved resulting symptoms such as severe pain and compression fracture [ 1 , 2 ] . a pathological fracture of the upper limb as an initial symptom of a late diagnosis of dtc is therefore extremely rare and has almost never been reported in literature . in this paper , we present a case of a patient with follicular thyroid cancer who presented with pathological fracture of the humerus without preceding illness . a previously fit and well 38-year - old man was presented to the emergency department with immediate extreme pain in the left arm after twisting it at home that day . plain radiographs of the left upper limb showed a fracture of the left proximal humerus associated with a lytic lesion ( fig . 1 ) . 
 figure 1:x - ray showed lytic lesion and pathological fracture of left proximal humerus . plain radiographs of the left . an urgent staging magnetic resonance imaging ( mri ) of the left humerus demonstrated a fairly   well - defined destructive lesion of proximal left humerus , which measured ~6 cm craniocaudally ( fig . both the cortex and the marrow were diffusely infiltrated and there was a small extra - osseous tumour mass anteriorly . computed tomography ( ct ) scan of thorax / abdomen / pelvis with contrast could not identify a clear primary source of malignancy but it showed an enlarged right lobe thyroid gland with retrosternal extension ( fig . 3 ) . 
 figure 2:mri left humerus showed pathological fracture of the neck and proximal shaft humerus , measure 6  2.5  2.8 cm in maximal dimension . an urgent staging magnetic resonance . figure 3:ct chest with contrast showed an enlarged right lobe thyroid gland with retrosternal extension causing compression and deviation of trachea ( arrow ) . mri left humerus showed pathological fracture of the neck and proximal shaft humerus , measure 6  2.5  2.8 cm in maximal dimension . an urgent staging magnetic resonance . ct chest with contrast showed an enlarged right lobe thyroid gland with retrosternal extension causing compression and deviation of trachea ( arrow ) . the thyroid lobe was investigated 6 years before where a multi - nodular goitre ( mng ) with a dominant solitary nodule on the right thyroid lobe was discovered . a fine needle aspiration cytology ( fnac ) specimen of the solitary nodule was reported as a thy2 with features consistent with a simple nodule . the investigations were arranged by the patient 's general medical practitioner who reassured the patient without the input of secondary services . following the finding of the ct scan , the patient was referred to the local ent department , where ultrasound of the neck and core biopsy of the thyroid nodule was conducted . the image confirmed a mng with largest nodule in the right lobe . and the core biopsy showed a follicular pattern with thyroid follicles of varying sizes set in a mixture of fibrous tissue . a ct guided biopsy of the left humerus after the initial presentation confirmed a metastatic thyroid cancer . histologically , the mass from the left proximal humerus demonstrated features consistent with metastatic thyroid carcinoma . a large thyroid lobe was found with no local invasion and four large level vi lymph nodes were excised . the pathologic findings confirmed complete excision of a 70 mm widely invasive follicular carcinoma with evidence of vascular invasion and metastasis of three out of the four central neck nodes . after thyroidectomy , the patient was seen by clinical oncology and radioiodine therapy was administered . the primary tumour is most likely found in breast and prostate followed by the thyroid gland . the bone metastases in dtc is osteolytic in nature and its distribution preferentially involves the weight - bearing skeletons such as vertebrae ( 52.5% ) , femur ( 20.4% ) , pelvis ( 16.0% ) and clavicle ( 13.6% ) . common manifestations of the osseous metastases include pain , fracture and spinal cord compression associated with lesion in the axial skeleton . in this case , we described an extremely rare scenario where pathological fracture of the upper limb was the initial presentation of metastatic dtc . of interest in our case is that the patient presented with a thyroid lump 6 years before which was diagnosed as a dominant nodule with a background of benign mng . in the absence of suspicious sonographic ultrasound features and benign pathocytological although ultrasound - guided fnac is an excellent tool for evaluating patients with solitary thyroid nodules , its utility in patients with mng has been questioned in the past . the british thyroid association ( bta ) recommends fnac should be carried out if ultrasound features are equivocal , indeterminate or suspicious of malignancy . in our case , fnac was performed although the nodule appeared benign and subsequent fnac result supported the findings that the nodule was benign in nature . despite this where fnac were conducted and proven to be benign in patients with non - functional , cervical mng the incidental thyroid cancer discovered at the time of thyroidectomy can be as high as 23% . male gender tends to be associated with an increased likelihood of cancer on final pathology [ 5 , 7 ] . in conclusion , despite the relative rarity of causing pathological fracture in the humerus , thyroid cancer should be considered during assessment of the patient with pathological fractures of unknown primary origin . although the gold standard for investigation thyroid nodule remains ultrasound - guided fnac , a benign fnac especially in male patients with a mng may need a more aggressive management due to the increased risk of an undetected thyroid cancer .
differentiated carcinomas of the thyroid gland usually have a good prognosis with prognosis often discussed in terms of 20 year survival . 
 nevertheless its 10-year - survival rate decreases when accompanied by distant metastasis . 
 follicular thyroid cancer ( ftc ) is the second most common thyroid cancer and usually presents with a solitary thyroid nodule with or without cervical lymphadenopathy . 
 distance metastasis at initial diagnosis is seldom observed with incidence range from 1 to 9% . in cases of bone metastasis , 
 the incidence is only 23% and weight - bearing skeleton is preferentially affected . in our case , we present a patient with ftc that metastasized to the upper limb causing severe pain and pathological fracture at the initial presentation .