A case of a horseshoe appendix
© The Author(s). 2016
Received: 13 July 2016
Accepted: 9 November 2016
Published: 23 November 2016
Anomalies of the appendix are extremely rare, and a horseshoe appendix is even rarer. A literature search has revealed only five reported cases. In this report, we present a case of a horseshoe appendix.
A 78-year-old man was referred for further examination following a positive fecal occult blood test. A mass in his ascending colon was detected on colonoscopy, while computed tomography showed that it was connected to the appendix. Tumor invasion derived from the ascending colon or appendix was suspected. We diagnosed ascending colon cancer prior to laparoscopic ileocecal resection. Macroscopic findings showed that the appendix connected to the back side of the mass, while microscopic findings showed that the mucosa and submucosa were continuous from the appendiceal orifice in the cecum to the other orifice in the ascending colon, where a type 1 tumor was observed on the orifice. We eventually diagnosed the patient with tubulovillous adenoma and a horseshoe appendix.
A horseshoe appendix communicates with the colon at both ends and is supplied by a single fan-shaped mesentery. Cases are classified by the disposal of the mesentery and the location of the orifice. Anatomical anomalies should be considered despite the rarity of horseshoe appendices.
Anomalies of the appendix are extremely rare. There have been several reports on the absence or duplication of the appendix. However, a literature search revealed only five reported cases of a horseshoe-shaped appendix [1–5]. In this report, we present a case of a horseshoe appendix that was incidentally found during resection of an adenoma in the ascending colon.
Anomalies of the appendix are extremely rare. In a study by Collins, from among 50,000 appendix specimens, there were four cases of agenesis and two of duplication . Duplications of the appendix were classified by Cave in 1936  and modified by Wallbridge in 1963  and Biermann in 1993 . However, there were some cases that could not be classified using this classification (e.g., triplets of the appendix, horseshoe appendix).
Cases of a horseshoe appendix
Detection of a horseshoe appendix
Mesko TW et al.
Sigmoidectomy + appendectomy
DasGupta R et al.
Suturing perforation + appendectomy
Calotă F et al.
Cem ORUÇ et al.
Ch Gyan Singh
Adenoma in ascending colon
Laparoscopic ileocecal resection
The classification of appendiceal anomalies
1. Agenesis: absence of appendix
2. Duplex appendix
A: partial duplication with both appendices sharing a common base like “Y-shaped” on a single cecum
B: complete duplication of the appendix on a single cecum
•B1 avian type: two appendices symmetrically placed on either side of the ileocecal valve
•B2 tenia-coli cecum type: one appendix arising from the usual site of the cecum and the other arising from the cecum along the tenia
•B3 tenia-coli hepatic flexure type: one appendix arising from the usual site of the cecum and the other arising from the hepatic flexure of the colon along the tenia.
•B4 tenia-coli splenic flexure type: one appendix arising from the usual site of the cecum and the other arising from the splenic flexure of the colon along the tenia.
C: duplication of the cecum, each having its own appendix
3. Triplex appendix: complete triplication of appendix on the cecum
• Shape anomalies
Disposal of the mesentery
• Sagittal disposal: the both bases of the appendix along the tenia in sagittal direction
• Frontal disposal: the bases of the appendix not on the tenia
Location of the orifice
• Cecum-ascending colon
In this classification, anomalies of the appendix are classified by number (e.g., agenesis, duplication, and triplet) and shape (e.g., horseshoe), while anomalies of the horseshoe appendix are further classified by the disposal of the mesentery and the location of the orifice.
Although most surgeons will not experience anomalies of the appendix, including the horseshoe appendix, anatomical anomalies of appendix should nevertheless be considered, despite their rarity.
All authors participated in the management of the patient in this case report. KT performed literature review and drafted the manuscript. JI supervised the case and also supervised the writing of the manuscript. YS is a chairperson of our department and supervised the entire process. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.
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