British Journal of Radiology (2004) 77, 248-249
© 2004 British Institute of Radiology
doi: 10.1259/bjr/65763747
Appearance of a Type B duplex appendix on barium enema
P Peddu, MRCS
and
P S Sidhu, MRCP, FRCR
Department of Radiology, Kings College Hospital, Denmark Hill, London SE5 9RS, UK
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Abstract
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Anomalies of the appendix are rare and are usually found in the adult population as an incidental finding during the course of surgery. We describe the appearances of a Type B duplicated appendix demonstrated on a barium enema for the first time. A review of the literature is presented with a discussion of different forms of duplicated appendices and the clinical significance of this finding.
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Introduction
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Anomalies of the appendix are rare and are usually found in the adult population as an incidental finding during the course of surgery. We describe the appearances of a duplicated appendix demonstrated on barium enema.
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Case report
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A 72-year-old man was referred to the radiology department for investigation for the cause of rectal bleeding. A barium enema was performed which revealed diverticulosis and no other mucosal abnormality to account for the rectal bleeding. Incidentally, two appendices were seen to arise from the posteromedial aspect of the caecum, in close relation to the ileocaecal valve (Figure 1
). The caecum was normal and correctly located in the right iliac fossa. A review of the clinical notes and previous investigations revealed no clinical history of note.
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Figure 1. (a) Supine overcouch view of the barium enema examination, demonstrating two appendices (arrows) and diverticulosis of ascending colon. (b) Magnified focused view of the caecum, demonstrating two appendices (arrows) arising in close relation to the ileocaecal valve.
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Discussion
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Variation in the size and position of the appendix is a common finding but duplication is rare. Examination of 50 000 histological appendix specimens revealed just two instances of congenital duplication [1]. Further cases have since been reported [2–10] with the true incidence of duplicated appendix estimated at 0.0004% [11].
A classification of duplication of the appendix, based on reported cases, was devised and divides these duplications into three types [12]:
i) Type A consists of various degrees of partial duplication on a normally localized appendix with a single caecum.
ii) Type B consists of a single caecum with two completely separate appendices, divided into two further subgroups, Type B1 where two appendices are located symmetrically on either side of the ileocaecal valve, resembling the normal arrangement in birds and termed "bird-like type" and Type B2 which has a normally located appendix arising from the caecum at the usual site and a second separate rudimentary appendix located along the line of one of the taenia and as such termed "taenia-coli type".
iii) Type C consists of a duplicated caecum each with an appendix.
The present case resembles the Type B1 ("bird-like type"). A Type C duplicated appendix has previously been demonstrated on barium enema, but the present case is the first description on a barium enema of a Type B1 duplicated appendix [13]. Some authors have since described further types of complex multiplicity of the appendix; for example "horseshoe appendix" [14] and "triple appendix" [7], but described at surgery and not on a barium enema examination. When anomalies of the appendix are detected in childhood they are nearly always associated with severe intestinal, genitourinary or bony malformations, seen most often in conjunction with Type B1 and C duplications [3, 7, 10].
Duplication of appendix must be distinguished from solitary diverticulum of the caecum, a difficult differentiation best made by histological examination. A diverticulum of the caecum is normally sited on the inner aspect of ileocaecal angle, and the wall of the diverticulum does not demonstrate lymphoid tissue microscopically [12]. A further abnormality that should be considered in the differential diagnosis is diverticulosis of the appendix, seen in 0.004–2.1% of specimens [15].
Although duplication anomalies of the appendix are uncommon they have clinical and medicolegal significance. Maizels [16] reported a case in which a child had appendectomies performed twice in a 5 month period and Bluett [8] described a case of duplication of appendix mimicking adenocarcinoma of the colon; greater awareness of the condition amongst surgeons is important [17].
In conclusion, duplication of the appendix is an uncommon anomaly, to the best of our knowledge has only once been described on a barium enema examination (Type C) but is of practical importance in surgical practice.
Received for publication October 7, 2002.
Accepted for publication June 11, 2003.
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References
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Abstract
Introduction
