The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 24 (page 112)

Chapter 24

Adult Hypertrophic Pyloric Stenosis

Although cases of hypertrophy of the pyloric musculature in adults (AHPS) had been reported previously, Morton (l930) first concluded that the condition seemed to constitute a definite clinical entity. He described 3 cases, aged 63, 42 and 39 years, in each of in each of whom radiographic examination had shown a constant, tubelike narrowing of the pyloric ring and immediate prepyloric area, 2.5 to 3.0 cm in length in one of the cases. (Measurements were not given in the other two). At operation the lesion was found to be due to hypertrophy of the pyloric muscularis externa in all instances; there were no associated lesions such as gastric or duodenal ulceration.

Kirklin and Harris (l933) described the radiographic signs of AHPS as elongation and narrowing of the pyloric canal together with evidence of gastric outlet obstruction. While these signs were not pathognomonic, a distinctive sign was a concave indentation of the base of the duodenal bulb, produced by partial invagination of the hypertrophied pyloric muscle into the duodenum. (Comment: It has subsequently been shown that various other conditions, ranging from normal contraction of the pyloric sphincteric cylinder to pyloric carcinoma, may produce similar duodenal indentation, as described in Chapters 13 and 33). In 50 cases of pyloric muscular hypertrophy in adults associated lesions of the upper gastrointestinal tract, such as gastric and duodenal ulceration, were present in 35.

North and Johnson (l950) stated that many cases of secondary pyloric hypertrophy, i.e. cases in whom the hypertrophy was associated with either benign or malignant gastric ulceration, had been reported prior to that time. The associated lesion was often situated away from the pyloric region in the more proximal part of the stomach. In primary AHPS, on the other hand, there were no associated gastric lesions. They were able to collect 59 case reports of verified primary AHPS, and described 5 cases of their own. It was stated that the lesion was not always easily recognizable at operation, a firm mass, or at least a thickening, being usually but not invariably palpable. When the condition was suspected, and when the exterior of the stomach appeared normal, a gastrostomy with examination of the lumen and palpation of the wall was necessary. Although the normal variations in the thickness of the pyloric musculature had not been clearly defined at that time, Truesdale (1915) had previously determined that the normal thickness of the "sphincter" (presumably referring to the pyloric ring) was 5.0 mm on an average, while Horwitz et al. (l929) found the range in thickness to vary from 3.8 to 8.5 mm with an average of 5.8 mm; both made their measurements upon fixed specimens in which the "sphincter" had been sectioned. North and Johnson (l950) found that in most of the recorded cases of primary AHPS in which data were available, the pyloric muscle measurements were considerably above this normal range and the same applied in their cases. The outstanding pathological feature of the lesion was hypertrophy and hyperplasia of the circular muscle layer, which was thickest at the pyloric ring, diminishing gradually over the "antrum" for a distance of 3.0 to 4.0 cm. The longitudinal muscle coat might also show a moderate grade of hypertrophy and the submucosa and mucosa might contain foci of cellular infiltration, consisting of plasma cells, lymphocytes and some neutrophils. Macroscopically the condition caused an unyielding tumor occupying the distal 3.0 to 4.0 cm of the stomach. The macroscopic appearances of infantile hypertrophic pyloric stenosis (IHPS) and primary adult hypertrophic pyloric stenosis (AHPS) were almost identical.

McNaught (l957) described 5 cases of AHPS, in 3 of whom there was no associated lesion, while in 2 an associated gastric ulcer was found at operation. It appears from the description that the ulcer was away from (i.e. proximal to) the area of muscular hypertrophy in both cases. This author found the lesion in AHPS to be comparable to simple hypertrophic pyloric stenosis in infants, and to him it was clear that the lesion was limited to the canalis egestorius or pyloric sphincteric cyclinder, as postulated by Torgersen (1942).

Craver (l957) reported 11 cases of AHPS encountered during a 24 year period. In 5 of these there was no concomitant upper gastrointestinal lesion, in 3 there was associated gastric ulceration, in 2 associated duodenal ulceration and in one associated haemorrhagic gastritis. (Comment: It is not stated clearly what the location of the gastric ulcers was, but it appears if they were proximal to the area of muscular hypertrophy). The gross appearance at operation resembled that found in IHPS, with a firm, unyielding, fusiform or circular tumor mass occupying the distal 3.0 to 4.0 cm of the stomach. The consistency varied from that of soft rubber to cartilage and it was thickest at the pyloro- duodenal junction, thinning out gradually over the "antrum"; distally it stopped abruptly at the pyloric ring. In 8 of the cases measurements showed that the muscular thickness ranged from 12 to 20 mm, with an average of 15.4 mm. This was 2 to 3 times the average thickness (7.1 mm) found in a series of normal controls. Microscopically there was both hypertrophy and hyperplasia of the circular layer, the muscular fibres being increased in size as well as in number. There were no inflammatory changes or oedema.

In a series of 25 cases coming to laparotomy, Desmond and Swynnerton (l957) found associated gastric ulceration in 12, duodenal ulceration in 6, pyloric ulceration in one and mucosal prolapse in 2, while 6 cases had no associated lesion (some cases had more than one associated condition). At operation the lesion presented as a white, regular, glistening muscular mass with a normal serosa and a loose, lax submucosa. (Comment: The finding is similar to the appearance seen during experimental truncal vagal stimulation in canines as described in Chap. 32). It could readily be differentiated from a grey, irregular, infiltrative type of carcinoma.

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