however , it is difficult to determine an appropriate resection line using only the laparoscopic approach . for more appropriate resection , laparoscopic and endoscopic cooperative surgery ( lecs ) on the other hand , gastric plexiform angiomyxoid myofibroblastic tumor ( pamt ) has recently emerged as a new entity among gastrointestinal mesenchymal tumors which was first described by takahashi et al .   in 2007 . this is a rare tumor with equal gender distribution and occurs primarily in adults with a wide age range of 783 years [ 3 , 4 ] . however , the bland nuclear features , low proliferative index and absence of necrosis , vascular invasion , recurrence and metastasis in all cases of pamt reported to date justify its characterization as a benign tumor . suggested that vascular invasion and extragastric extension of the tumor were not typically observed in pamt . currently , distal or partial gastrectomy remains the treatment of choice . to our knowledge , a 39-year - old male patient visited our hospital because of epigastric pain . in an upper gastrointestinal endoscopy examination , gastroscopy revealed a 3.5  3.0 cm sessile polypoid mass with a smooth surface in the anterior wall of the gastric antrum with a recessed area . we considered that this tumor was located in the muscle layer ( fig .  1 ) . the ct scan showed a heterogeneous tumor in the gastric antrum , which was drastically enhanced with contrast medium , and consisted of a number of highly stained small nodules around the tumor rim ( fig .  2 ) . radiological imaging suggested differential diagnoses of angioma and solitary fibromyxoma because of the hypervascular nature of the tumor . however , because the tumor did not protrude into the lumen of the stomach , these diagnoses were unlikely . lecs combines laparoscopic gastric resection with endoscopic imaging for tumor location and determining an appropriate resection line . aggregations of small polypoid nodules , red - colored and angiomatous , were characteristically seen on the serous membrane surface , and appeared like a metastatic lymph node nodule ( fig . first , we located the tumor and cut the surrounding mucosa of the lesion by endoscope . we perforated the gastric wall at the distal side of the tumor using needle knife without injuring the pylorus . next , the seromuscular layer was dissected laparoscopically with an ultrasonically activated device tracing the mucosal line cut . a partial gastrectomy by lecs revealed the tumor at the antrum of the greater curvature side of the stomach , and the incision line was closed on suturing by layer - to - layer anastomosis . the tumor was composed of bland spindle cells which were separated by abundant myxomatous stroma and showed plexiform growth in the entire stomach wall ( fig . the tumor cells were negative for cd117 ( c - kit ) , cd34 and s-100 protein , but diffusely positive for smooth muscle actin consistent with predominant myofibroblastic differentiation ( fig . the tumor was especially characterized by multiple nodules protruding outward from within the serosa , and we diagnosed the patient with pamt . the patient received supportive care without any specific medication during hospitalization and had no recurrence or metastasis during follow - up for 9 months after the surgery . pamt is a rare mesenchymal tumor of the stomach , which consists of spindle cells with myofibroblastic characteristics . estimated that the frequency of pamt is less than 1/150 that of gastrointestinal stromal tumor , but only 28 cases of pamt have been reported , including the present case . the prevalence of pamt does not vary by sex ( m : f = 1 : 1 ) and it can develop at any age ( range : 783 years ) . there are few reports describing the ct findings for pamt [ 2 , 7 ] . they reported that ct findings of tumor location in the gastric antrum , a heterogeneous internal enhancement effect , and small nodules with a strong enhancement in the rim could be used for radiologic diagnosis of pamt . in our case , all three ct findings were evident . pamt is considered a benign tumor . however , due to its rarity , the true biological potential of pamt remains unknown . so , complete resection when functional preservation is possible is appropriate . on the other hand , lecs is the best procedure for complete resection while preserving the pylorus because of the gastric antrum of predilection for pamt . to our knowledge , when a myxoid spindle cell lesion is observed in endoscopic biopsy or when there are characteristic ct findings , pamt should be included in the differential diagnosis .
plexiform angiomyxoid myofibroblastic tumor ( pamt ) is a recently described distinctive gastric mesenchymal entity with a peculiar plexiform pattern , bland spindle cells and a myxoid stroma rich in arborizing blood vessels . in this study 
 , we report a new case of this rare gastric tumor resected by laparoscopic and endoscopic cooperative surgery ( lecs ) . 
 a 39-year - old japanese man was admitted with a gastric mass . 
 gastroscopy showed an elevated mass in the anterior wall of the gastric antrum . 
 endoscopic ultrasound examination revealed a focal hypoechoic lesion protruding into the lumen . 
 a partial gastrectomy by lecs was performed , and the patient made an uneventful recovery and remains well 9 months later . 
 the tumor in this case depicted all the typical histopathologic and immunochemical features of gastric pamt ( c - kit negative and smooth muscle actin - positive ) . 
 especially , it was characterized by multiple nodules protruding outward within the serosa . 
 therefore , it is important that the resection line is determined on the serosa to ensure the complete resection of these nodules together .