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Diagnostic Challenges in Right Iliac Fossa Mass Caused by a Fish Bone

Ahmad Ibrahim Yahaya,1 Ismail Burud,2 Jasiah Zakariaa1

1 Department of General Surgery, Hospital Tuanku Ja’afar, Jalan Rasah, 70300 Seremban, Negeri Sembilan, Malaysia

2 Department of Surgery, International Medical University, Clinical Campus, 70300 Seremban, Negeri Sembilan, Malaysia

Correspondence to: Dr. Ahmad Ibrahim Yahaya, Email:

Received: 07 December 2019; Revised: 01 June 2020; Accepted: 05 June 2020; Available online: 22 June 2020



Right iliac fossa (RIF) mass is a common condition seen by surgeons. Despite advances in diagnostic modalities, it remains a diagnostic and therapeutic challenge, hence many authors describe RIF mass as temple of surprises. We report a challenging case of a 35-year-old man who presented with a tender RIF mass. Abdominal ultrasonography (USG) and computed tomography (CT) scan abdomen were done and he was treated non-surgically. His symptoms recurred after one month and a CT scan abdomen was repeated which revealed a suspicious foreign body within the appendicular mass. Laparotomy was performed which showed a macerated appendix with a 4-cm long fish bone within. The role of diagnostic tools in managing RIF mass and the treatment modality of appendicular mass are discussed. In managing RIF mass, a surgeon must be aware of the various differential diagnoses, but common diagnosis should always be entertained. Multi-modal diagnostic tools must be considered, including serial imaging in different planes.


Keywords: Appendicitis, Right iliac fossa mass, Fish bone

Ann Afr Surg. 2021; 18(1):59–62


Conflicts of Interest: None

Funding: None

© 2021 Author. This work is licensed under the Creative Commons Attribution 4.0 International License.


Right iliac fossa (RIF) mass is a common condition seen by surgeons and involves diagnostic challenges in making correct preoperative diagnosis. Though appendicular mass is one of the most common diagnosis, ileo-cecal tuberculosis (TB), cecal carcinoma, non-Hodgkin’s lymphoma, iliopsoas abscess, Chron’s disease, urologic and gynecologic masses are other rare causes (1,2). Despite advances in diagnostic tools, RIF remains a diagnostic and therapeutic challenge, hence many authors describe it as a temple of surprises. This report presents a challenging case of a RIF mass which turned out to be an appendicular mass caused by a fish bone.

Case report

A 35-year-old man, known case of hypertension and bronchial asthma, presented with one-month history of non-radiating RIF pain, associated with two days of vomiting. He did not have fever, and denied any foreign body ingestion, abdominal trauma, or constitutional symptoms. He was generally well and was not septic or anemic. Per abdomen examination revealed tenderness and guarding at the RIF with a palpable mass measuring 4 cm × 4 cm. Biochemical markers showed leukocytosis (13,280/mm3), capsular-polysaccharide reactive protein (CRP) of 128 mg/L, and erythrocyte sedimentation rate (ESR) of 95 mm/hour.

Abdominal ultrasonography (USG) was suggestive of appendicular abscess. Computed tomography (CT) scan abdomen/pelvis showed a RIF mass which had no clear fat plane with adjacent transversus abdominis muscle, cecal pole and terminal ileum. The appendix was not visualized, and there was no foreign body noted (Figure 1). He was treated non-surgically with antibiotic for appendicular mass and responded well to treatment. He was discharged with a colonoscopy appointment in a month.

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The colonoscopy showed non-distensible cecum secondary to external compression with a polypoidal growth at the appendiceal opening. Histopathology examination (HPE) of the mass showed inflamed stromal tissue with mucin lake, but no malignant cells. In view of the suspicion of neoplasm, we arranged an early clinic appointment after the colonoscopy to discuss further intervention with patient; however, he defaulted on the follow up.

One month after the colonoscopy, he presented again with the same abdominal pain. This time, the RIF mass was clinically larger, measuring 7 cm × 7 cm. He was also investigated for tuberculosis. Mantoux test, acid fast bacilli sputum culture and smear, and TB polymerase chain reaction assay were sent, and confirmed negative for TB.

A CT abdomen/pelvis was repeated, which revealed a larger right iliac mass compared with the first CT scan. A suspicious foreign body within the appendicular mass was visible in the repeat CT scan (Figure 2), which was presumed to be not visible in the previous CT scan. The initial CT scan was reviewed again by the surgeons and radiologists in a multi-departmental conference and different planes (coronal and sagittal) were revised meticulously. To our surprise, the sagittal plane of the initial CT scan did reveal a suspicious thin, elongated foreign body within the appendicular mass (Figure 3), which was not clearly visualized in axial and coronal planes.

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Click to view figure 3

A diagnostic laparoscopy was done. Intraoperatively, the terminal ileum, cecum and omentum were densely adherent to the lateral abdominal wall. There was difficulty in identifying the appendix laparoscopically due to dense adhesion. Laparotomy was done and on mobilizing the caecum posteriorly, there was a small cavity with pus collection, containing a 4-cm long foreign body which appeared to be like a fish bone within macerated appendix (Figures 4-6). Right hemicolectomy and ileo-colic anastomosis were done. Postoperative recovery was uneventful, and the HPE confirmed the tissue as perforated appendicitis.