Inflammatory pseudotumors (IPTs) are benign masses arising from nonspecific inflammatory conditions including surgical invasion. We herein report the rare case of an IPT mimicking port-site metastasis in a 69-year-old patient who underwent retroperitoneal robotic partial nephrectomy for stage T1a renal cell carcinoma. Radiological examination performed six months after the surgery revealed the presence of a mass underneath the abdominal wall which coincided with a port site. The tumor was resected by laparoscopic transperitoneal approach, and histological examination led to the diagnosis of an IPT that consists of xanthogranulomatous inflammation. We also discuss the etiology of IPT formation and features distinguishing IPTs from port-site metastasis.
Inflammatory pseudotumors (IPTs) which are caused by nonspecific inflammatory conditions can develop at nearly every body site [
A 69-year-old Japanese male with diabetes mellitus underwent right-sided retroperitoneal RPN for an incidental renal tumor (Figure
Contrast-enhanced computed tomography shows a right renal tumor (arrow) with a maximum diameter of 27 mm.
Follow-up computed tomography (CT) scan performed six months after the surgery revealed an emerging small mass below the right side of the abdominal wall coinciding with a 12 mm AirSeal™ assistant port site (Figure
Appearance of a mass underneath in right side of the abdominal wall (arrow). (a) Contrast-enhanced computed tomography. (b) [18F]fluorodeoxyglucose- (FDG-) positron emission tomography-computed tomography shows increased FDG uptake with a maximum standardized uptake value of 3.2.
Tumor resection was subsequently performed by laparoscopic transperitoneal approach (Figure
Intraoperative image reveals a mass (circle) observed in the peritoneal cavity.
Histology of the mass at a port site showing aggregation of foamy histiocytes with lipogranulomas, mild infiltration of lymphocytes and plasma cells, and focal fibrosis.
IPTs are benign tumors which mimic malignant neoplasms and comprise cells associated with both acute and chronic inflammation. The pathogenesis and etiology of IPTs are unspecific; therefore, IPTs have been described under various names such as xanthogranuloma, inflammatory myofibroblastic tumor [
Schloffer’s tumor might be considered the diagnosis in the present case based on the potential etiology because it is possible that Vicryl™ suture or Surgicel™ used in RPN might have provoked a foreign body reaction. Asano et al. [
In the present case, the Surgicel™ bolster placed on the renal parenchymal defects was nearly invisible at the IPT site. This image finding shows that the Surgicel™ bolster was normally diminished with time after surgery [
While the exact cause of IPT in the present case remains unknown, we speculate that the following two processes were more likely etiologies. The first one is chronic inflammation by microabscess formation underneath the abdominal wall, which might be partially due to diabetes mellitus. The second is the involvement of FN. Fat fragments produced in RPN might migrate to a port site and subsequently develop FN provoking chronic inflammation. Amblee and Ganesh [
The preoperative differentiation between IPT and PSM of RCC is difficult because of the rarity of both conditions, which were reported in very few case reports [
Song et al. [
The authors declare that they have no conflicts of interest.
We acknowledgement Enago for English language review.