Partial or Intramural Gastric Diverticulum #
The term partial gastric diverticulum was first used by Samuel (l955) to indicate a projection of the mucosa into, but not through the muscular coats of the stomach. As it does not extend as far as the serosa, external inspection of the stomach at operation will not reveal any abnormality. He described a case, diagnosed by radiography and subsequently confirmed at operation, in whom a partial diverticulum was located on the greater curvature of the pyloric "antrum" approximately 1.0mm orally to the pyloric ring. It was surrounded by a shallow, smooth-walled defect which was considered to be due to oedema. Radiographically it had to be differentiated from a gastric ulcer, a small ulcerated tumor and ectopic pancreatic tissue (in which barium-filled ducts might resemble small diverticula) (Chap. 21). However, these conditions could be excluded because of the smooth outline and narrow neck of the diverticulum, the normal mucosal pattern in its vicinity and the absence of associated spasm.
Flachs et al. (l965) described 2 similar cases. In both the partial diverticulum was situated on the greater curvature close to the pyloric ring. In one of the cases it was mistaken for a gastric ulcer, resulting in partial gastrectomy. The resection specimen showed a mucosal pouch protruding into the submucosa, with the muscular layer intact and the serosa smooth and glistening. It was pointed out that a mucosal pouch could show variable filling with barium during the radiographic examination; the surrounding musculature might contract to such an extent that it could disappear almost completely. In contrast, a gastric ulcer showed little change in appearance.
Rabushka et al. (l968) described the radiographic appearances of a case (confirmed at operation) in which a partial diverticulum, entirely contained within the wall of the stomach, was situated on the greater curvature 4.0 to 5.0 cm proximal to the pylorus. (In another case a diverticulum on the greater curvature of the pars media was also considered to be of the intramural variety, but this was not proved and it could possibly have been a "conventional" diverticulum).
The condition is rare. Treichel et al. (l976) encountered 4 patients (one of whom had 2 intramural diverticula) during the course of 10,000 routine upper gastrointestinal barium investigations. All cases were confirmed by endoscopy and 2 also by operation. The diverticula typically occurred on the greater curvature of the "antrum" within 1.0 to 4.0 cm of the pylorus, measured 4.0 to 10.0 mm in diameter, presented as round or oval pouches with narrow necks, and changed to some extent in size and shape during contraction of the walls. Complete filling of a diverticulum could be achieved by administering a spasmolytic during a double contrast examination. In the case where radiography showed 2 diverticula, endoscopy initially failed to reveal the lesions; however, they were visualized at a second attempt. It was stated that the lesions were easier to detect by radiography than by endoscopy.
Treugut and Olsson (l980) described another case in which the lesion typically presented at radiography as a smooth-walled, lenticular, intramural outpouching on the greater curvature of the "antrum" approximately 3.0 cm proximal to the pylorus. It varied somewhat in size but never exceeded 10.0 mm in diameter. The ostium was surrounded by a circular fold; in other respects the mucosal folds were normal, which differentiated it from a gastric ulcer and an ulcerated tumor. Confirmation was obtained by endoscopy and operation.
Cockrell et al. (l984) encountered reports of 13 cases in the literature and added 3 of their own. To them the striking feature was the unique location of the lesion on the greater curvature of the "distal antrum". There was no explanation for its occurrence in this particular situation and the etiology remained unknown.
Dickinson and Freeman (l986) reviewed the radiographic and endoscopic features of the condition and described 6 cases of their own. All were diagnosed at radiography, 4 being confirmed by endoscopy. It was pointed out that while a partial gastric diverticulum was a rare and clinically insignificant lesion, it was liable to cause diagnostic confusion and might lead to inappropriate treatment (e.g. partial gastrectomy) if not recognized.
We have encountered the following 3 cases of intramural gastric diverticula during the last 13,600 upper gastrointestinal barium investigations.
Case Reports
Case 22.1. M.W., 55 year old female, complained of cramp-like epigastric pains diurnally and occasionally nocturnally after a late evening meal. At times she felt nauseous. Physical examination revealed signs of chronic bronchitis and iron deficiency anaemia. Gastroscopy showed a sliding hiatus hernia without oesophagitis. No evidence of ulceration or other lesion was seen in the stomach and duodenum. A second gastroscopy six years later showed no abnormality in the oesophagus, stomach and duodenum. Repeat gastroscopy the following month was difficult due to lack of patient co-operation. The oesophagus was normal. The pyloric region appeared somewhat hyperaemic and oedematous, the remainder of the stomach being normal. The duodenum could not be visualized. Barium radiographic examination at that time showed a small diverticulum on the greater curvature of the pyloric sphincteric cylinder approximately 2.5 cm proximal to the pyloric ring (Fig. 22.1A). Its neck, which was surrounded by a shallow, smooth-walled indentation of the barium in the lumen, was 0.7 mm in diameter. During contraction of the cylinder it was seen to be situated midway between the right and left pyloric loops (Fig. 22.1B) in the situation where the pyloric pseudo-diverticulum occurs normally (Chap. 13). At times, during near maximal contraction of the cylinder, it disappeared, only to reappear during the next cycle of filling.
A | B |
| Fig. 22.1. A Case M.W. Small intramural diverticulum (arrow) on greater curvature of pyloric sphincteric cylinder 2.5 cm proximal to pyloric ring. B Case M.W. Partial contraction of sphincteric cylinder. Intramural diverticulum (arrow) situated on rim of physiological pseudodiverticulum (PD), midway between right and left pyloric loops | |
Because of the features enumerated in the discussion it was diagnosed as an intramural or partial gastric diverticulum. It was certainly not an ulcer as witnessed by repeated gastroscopies. The fact that it was not seen at gastroscopy does not come as a surprise as Treichel et al. (l976) had found that the lesion was easier to detect by radiography than by endoscopy. Cockrell et al. (l984) stated that an intramural diverticulum may be difficult to detect endoscopically if its ostium is hidden by a fold or if it occurs in an area which is contracting.
Case 22.2. G.V., 32 year old female, complained of a vague feeling of fullness and
occasional pain in the epigastrium. Physical examination revealed some epigastric
tenderness. After a month's treatment with antacids the symptoms disappeared.
Radiographic examination at that time showed a small diverticular-like structure on the
greater curvature of the pyloric sphincteric cylinder approximately 3.0 cm proximal to the
pyloric ring, i.e. midway between the right and left pyloric loops, in the position where
the pyloric pseudo-diverticulum usually occurs (Fig. 22.2
Case 22.3. J.V., l9 year old female, complained of "acidity", of several months'
duration. Gastroscopy showed mucosal erosions in the lower oesophagus, probably due
to reflux oesophagitis. The gastric fornix and corpus were normal; on the greater
curvature of the "antrum" a "pseudodiverticulum" was seen. Radiographic examination
14 months later, for the same complaint, showed an intramural diverticulum on the
greater curvature within 2.0 cm of the pylorus. Cyclical contractions of the pyloric
sphincteric cylinder were normal; during contraction of the right and left pyloric loops, a
normal, physiological pseudodiverticulum was seen with an intramural diverticulum on
its greater curvature aspect (Fig. 22.3).
According to Cockrell et al. (l984) the striking feature of the lesion was its unique
location on the greater curvature of the "distal antrum". No ready explanation could be
found for its occurrence in this particular situation and the etiology remained unknown.
We believe the explanation probably lies in the anatomical build of the pyloric
sphincteric cylinder as described previously (Chap. 3). In all 3 our cases the intramural
diverticulum occurred on the greater curvature between the right and left pyloric loops, a
fact which became clear during contraction of the loops. In this region the musculature
of the cylinder is at its thinnest; it is surmized that the intramural diverticulum consists of
a projection of mucosa and submucosa into the relatively sparse muscle fibres. It is best
visible when the region is distended, becoming compressed or smaller during contraction
of the muscular rings and intervening musculature. According to the descriptions of
Samuel (l955), Flachs et al. (l965), Treugut and Olsson (l980) and Cockrell et al. (l984)
their cases will also fall into this category, and so will some of the cases described by
Rabushka et al. (l968), Treichel et al. (l976) and Dickinson and Freeman (l986).
An intramural gastric diverticulum should not be confused with the pseudo-diverticulum
of the pylorus, which is a fleeting, physiological outpouching of all layers of the wall
occurring normally during contraction of the sphincteric cylinder (Chap.13). An
intramural gastric diverticulum may be seen on the greater curvature aspect of the
physiological pseudodiverticulum during a stage of contraction of the sphincteric
cylinder.
Whether it is a congenital or acquired lesion, is not known.
A 
B 
Fig. 22.2. A
Case G.V. Intramural diverticulum (arrow) on greater curvature
of sphincteric cylinder 3.0 cm proximal to pyloric ring.
B Case G.V. Contraction of sphincteric cylinder. Intramural
diverticulum (arrow) between right and left pyloric loops now smaller
Fig. 22.3.
Case J.V. Normal contraction of pyloric muscle torus (MT) and right (RPL)
and left (LPL) pyloric loops. Intramural diverticulum (arrow) on rim of physiological
pseudodiverticulum (PD)
Discussion
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References
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