gossypiboma ( retained surgical sponge ) describes a mass of cotton or sponge that is left behind in the body cavity during a surgical operation . these foreign bodies can often mimic tumors or abscesses when detected clinically or with radiation . in fact , surgical sponges without opaque markers are the leading cause for the difficulty of a correct diagnosis . here , we present a case in which a foreign body , gauze without radiopaque markers , was left behind during a procedure that involved the removal of an intrapelvic tumor . after a computed tomography ( ct ) scan had revealed information leading to an inaccurate diagnosis , an accurate diagnosis of gossypiboma was successfully made using endoscopic ultrasound - fine - needle aspiration ( eus - fna ) . a 60-year - old female patient was referred with an unexpected detection of an intrapelvic tumor during a routine ct scan . the patient 's medical history included a hysterectomy and a left side ovariectomy at the age of 27 . the ct scan revealed a 45 mm tumor in the patient 's pelvis [ figure 1a and b ] , which was diagnosed as a gastrointestinal stromal tumor ( gist ) , a chronic expanding hematoma or leiomyoma . a forward - view eus ( tgf - uc260j , olympus optical co. , tokyo , japan ) identified a low echoic lesion when scanned from the sigmoid colon . fna was performed with a 22-gauge needle ( ezshot2 , olympus optical co. , tokyo , japan ) by using the forward - view eus [ figure 2 ] . examination of the fna specimen revealed a foreign body ( string of gauze ) displaying macrophage cells and necrotic tissue [ figure 3 ; hematoxylin and eosin , original magnification 40 ] . during the surgery , histological examination of the tissue adjacent to the foreign body revealed granuloma formations with fragmented silken threads [ figure 4 ; hematoxylin and eosin , original magnification , 100 and 200 ] . a : sagittal section ( black arrow ) ; b : horizontal section ( black arrow ) . endoscopic ultrasound ( eus)-fine - needle aspiration using forward - view eus a foreign body ( string of gauze ) obtained using the 22-gauge needle , with macrophage cells and necrotic tissue granuloma formations with fragmented silken threads gossypiboma describes a mass of cotton or a sponge that is retained in the body after a surgery . gossypiboma causes foreign body reactions of the surrounding tissue since they are inert and show no specific decomposition . in this case , radiopaque sponges were not used , and there were no adverse symptoms in the 30 years postsurgery . the typical appearance of gossypiboma shows a spongiform pattern with gas bubbles . in typical cases , however , it can be difficult to diagnose the disorder with ct scans in cases without gas bubbles . in the case described in this paper , radiologists using findings from a ct scan , initially and incorrectly diagnosed the lesion as gist with fibrosis . however , the disorder was correctly diagnosed by a team of gastroenterologists using eus - fna . the eus - fna procedure revealed a segment of string in a fixed foreign body in the pelvis . the application of eus using curved linear array ( cla ) endoscopes in the lower gi tract has been limited to the rectum and distal sigmoid colon because of the oblique - viewing optics . there were case reports using oblique - viewing cla echoendoscopes to evaluate lesions proximal to the sigmoid colon , but advancement of the cla echoendoscope beyond the sigmoid required the use of an overtube or a guide wire previously placed with a colonoscope . binmoeller et al . have reported the feasibility and safety of the front - view forward - array echoendoscope for evaluating right colon lesions . thus , we used a front - view forward - array echoendoscope to safely evaluate the intrapelvic tumor and sample the tissue . a correct diagnosis was obtained using this method . in summary , this is the first known case report diagnosing gossypiboma by eus - fna .
gossypiboma is a term used to describe a foreign mass within the body that is composed of a cotton matrix . 
 gossypiboma can cause infection or abscess formation from an early stage , or it can remain clinically silent for many years . 
 gossypiboma can be diagnosed using several methods including abdominal x - ray films , us of the abdomen , contrast - enhanced computed tomography of the abdomen , and during surgery . 
 however , the variable appearance of gossypiboma can lead to diagnostic misinterpretations . here , we report a successful diagnosis of gossypiboma using a novel method , that is , endoscopic ultrasound - fine - needle aspiration .