Abdominal Wall Abscess Caused by Small Intestinal Penetration That Was Difficult to Distinguish from a Malignant Tumor: A Case Report

Abstract

Introduction: Fish bone ingestion is common but rarely causes complications such as abdominal wall abscesses, which can mimic malignancies such as sarcomas on imaging. Abscesses require drainage and antibiotics, while sarcomas need wide excision. Therefore, the differentiation between abscesses and sarcomas is important and often requires multidisciplinary involvement.

Case presentation: A 70-year-old woman presented with anorexia and a painful abdominal mass. Laboratory tests showed inflammation but normal tumor marker concentrations. The abdominal wall mass was hard and poorly mobile. Ultrasound showed a heterogeneous, mosaic-like internal structure, and CT and positron emission tomography-CT findings strongly suggested a malignant tumor such as sarcoma. We performed surgery and confirmed the presence of an abdominal wall abscess with small intestinal penetration caused by an ingested fish bone. The small intestine was partially resected, and pathology showed no malignancy. The patient recovered well and was discharged on postoperative day 9. The final diagnosis was an abdominal wall abscess caused by an ingested fish bone that perforated the small intestine.

Conclusions: We present a rare case of an abdominal wall abscess caused by penetration of the small intestine by an ingested fish bone.

Keywords: abdominal wall abscess; fish bone; foreign body ingestion; laparoscopic-assisted surgery.

Fig. 1. Imaging examinations at the initial visit. (A) Ultrasound shows a heterogeneous, mosaic-like internal structure (yellow arrows). (B) Enhanced CT (horizontal) shows an 8-cm low-density tumor in the left side of the abdominal wall (yellow dotted circle). (C) Enhanced CT (sagittal) shows that the tumor is in contact with the small intestine (yellow dotted circle; red arrows indicate the small intestine). (D) Dynamic MRI shows that the tumor has high signal intensity on T2-weighted imaging (yellow dotted circle). (E) Positron emission tomography-CT shows fluorodeoxyglucose uptake corresponding to the solid component of the tumor. The mass was suspected to have spread into the abdominal cavity, a finding suggestive of malignancy (yellow dotted circle).

Fig. 2. Physical findings and ultrasound 1 week after the first hospital visit, and enhanced CT images obtained on the 11th day after drainage. (A) The patient developed redness over the palpable mass. (B) Ultrasound shows increased fluid content in the lesion (yellow arrows). (C) Horizontal image shows that the low-density tumor shrank after abscess drainage (yellow dotted circle). (D) Sagittal image shows a new linear high-density structure (yellow circle).

Fig. 3. Surgical findings. (A) The small intestine and omentum are in a mass, and there are strong adhesions between the mass and the abdominal wall. (B) There is a 2-cm-long fish bone. (C) The abdominal wall abscess involves the small intestine, which has been partially resected. (D) The resected specimen shows the connection between the small intestine and the abscess.