尿道狹窄の臨床的並に組織学的研究

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Urethral stricture, a serious and peculiar condition, has hitherto been regarded as being a complication of severe gonorrheal infection or resulting from unusual traumas. It has, therefore, been thought that the condition would decrease if gonorrhea were prevented or cured. In the medical literature of Japan and abroad, no systematic studies, aside from statistical observations, have been published. However, the existence of this condition still persists today and the patients suffering from it are as numerous and pitiful as in the past. The author has for many years been investigating this problem under the supervision of Prof. Tabayashi and the results so far obtained, though by no means complete, are here presented. The materials used in this study include 122 cases of urethral stricture, of which 31 patients have been treated by surgical operations. The urethral tissues involving the stricture were removed and the specimens were studied from many angles in serial sections. Hence, the present observations and discussions are based chiefly on the histological changes consequent to the stricture. 1. Etiology. The most frequently cited cause of urethral stricture in the literature is gonorrhea in nearly all cases, together with a few which resulted from trauma or from undue manipulations at the time of operations. Gonorrhea, trauma or tuberculosis as causes of stricture have thus been considered to be the main causes of urethral stricture, but in the author's study a fourth distinct cause has been discovered, which is rather difficult to define but quite characteristic and even specific. Gonorrhea responds to chemotherapy and this fact neutral reduces the incidence as well as complications of stricture. Trauma, on the other hand, shows a tendency to increase because of multiplying occupational hazards associated with development of heavy industry and skyscraper construction, dissemination of high speed vehicles and utilization of stones and procelains in buildings and furnitures. There is a certain number of patients with stricture of non-specific and not cleary definable cause. Tuberculosis constitutes approximately one-third of the causes of stricture, as with trauma and gonorrhea, according to statistical surveys. There is little doubt that some discrepacies are bound to enter into such statistics according to the environmental influences. In any case, the most predominant cause is gonorrhea, followed by trauma, and not a few due to an unknown but rather specific cause. Tuberculosis, though definite in etiological relationship, plays only a minor role. 2. Incidence. The total number of 122 cases here studies represents an incidence of only 1.44 per cent of the 8,432 patients treated in our department, which is probably the lowest figure ever reported in the literature at present. The cause in these cases include gonorrhea 69.67 per cent, trauma 16.39 per cent, unknown cause 9.01 per cent and tuberculosis 4.91 per cent, excluding those due to congenital anomalies, operative complications or urethral stones. 3. Location. The location of stricture is customarily described either by anatomical designation or by measurement of distance from the external urethral orifice, but these methods are complicated and often inaccurate. In the majority of cases the present practice is to determine by urethrography, and, utilizing this method, the author simply distinguishes the locations as anterior urethra, bulbo-membranous urethra and membranous-prostatic urethra. However, the stricture occurring in the portion between the internal orifice and prostate as well as the one situated at the external orifice have been excluded, since the former is difficult to be differentiated from prostatic hypertrophy, while the latter comprises many instances of congenital defect. Consequently the materials here used consist of 27 cases of stricture occuring at the bulbo-membranous portion, and 4 cases situated at the anterior urethra. 4. Histology. All histological observations were made by the use of serial sections, both transverse and longitudinal, of tissues obtained at operations consisting of circular pieces of tissues surrounding the involved area, varying in lengths from 1 to 4.5 cm. In cases in which the stricture occurred in more than one location, the adjacent tissues of about 6 cm in length were obtained. a) Urethra proper. The stricture occurs as centripetal, centrifugal or branched structures in 2-4 streaks resulting from mucosal adhesions, or even as distinct spiral formations. The urethral mucosa thus forms a narrow constriction leading finally to either incomplete or complete atresia. b) Mucosal epithelium. The mucosal epithelium of the urethra proper presents a striking picture of metaplasia or hyperplasia, made up to 10-40 layers. The same is true of the branching tubes and of paraurethral passages. The excretory ducts of Cowper's glands are only moderately involved. There is sometimes papillary or basalioma formation. c) Subepithelium. The subepithelial connective tissue shows compact and sclerotic or even hypertrophic transformation and the resulting picture is often so complex that it is difficult to describe even in a summary. Briefly stated, in the sclerotic portions, there may be clearly visible the admixture of connective tissue fibers in a waved manner, and in the clcatrization portions these fibers present as an appearance of piled wooden boards. Furthermore, in the neighborhood of deep portions showing a transition to the muscle layer, the fine muscle fibers are seen to be embracing the connective tissus fibers, suggesting a relationship with the changes in the muscle fibers of these transition areas. d) Cowper's glands. Most of the specimens examined contain Cowper's glands and their excretory ducts. The epithelium of the proximal urethra exhibits the influence of changes above described, although in a limited extent. Reduction and atrophy of the glandular parenchyma are also noted. The fact that some portions of Cowper's glands are so frequently found in the sclerotic tissues removed by operation indicates the existence of a relationship, either direct or indirect, to urethral stricture. e) Corpus spongiosum. There are many specimens in which structures clearly identifiable as corpus spongiosum can be detected. The majority of these structures may be regarded as representing the results of either compression or atrophy. Although numerical and morphological changes of the cavity spaces are omitted from the discussion because of their complexities, the definite effects of these changes are evident, since the constriction, atresia or hypertrophy of walls is clearly visible. f) Elastic fibers. It is commonly believed that the elastic fibers are reduced in the tissues involved in stricture, but in the present materials these fibers are generally prominent. In clcatrix areas they are seen running as fine fibrils, so that at least in a few specimens they even present pictures of elastosis which may occur either diffusely or circumscribed. No accurate statement can be made, however, on this point until strict comparison with normal tissues is made inasmuch as the urethra is characterized by a definite organ specifity. Further studies on this problem are to be made. g) Cellular infiltrations. In strictures of gonorrheal origin either generellized or localized cellular infiltrations are noted just as in chronic gonorrheal tissues, running a course of 10 or more years. These are not seen in strictures of traumatic or unknown cause. In tuberculous strictures the infiltrations of inflammatory cells characteristic of tuberculosis are usually found. 5. Hypertrophy of vascular walls. The endothelium and the media of arterioles and venules situated in the relatively deep portions of the sclerotic connective tissue frequently show either marked or profound hypertrophy. The degree of such changes vary according to the duration of the disease. The same is true of the venous sinusoids of the spongiosum, and may be solitary or in groups. These vascular wall changes are seen in all four types of stricture regardless of causes, and hence they may be considered to be characteristic of stricture. 6. Pathogenesis. Although the etiology of stricture may be classified into gonorrbeal, traumatic, unidentified (either specific or non-specific) and tuberculous, the histological changes to belong to one category, with the exception of cellular infiltrations peculiar to gonorrhea. These changes consist of metaplasia or hyperplasia of the epithelium, proliferative hypertrophy of the arteriolar and venule walls. When these changes are sought in diseases characterized by the proliferation of collagen fibers and vascular wall hypertrophy, they resemble those seen in so-called rheumatic conditions which are generally interpreted to represent a type of allergic disease. Although very little is found in the literature as to whether the urethra is amenable to allergic changes, it is readily conceivable that this organ in subjected to the influences of antibiotics employed in the treatment of gonorrhea, tuberculosis and trauma, producing conditions favoring the performance of antigen-antibody reactions. Assuming the conditions so created even without knowledge of the patient as being due to an yet unidentified specific or non-specific cause, the histological findings above described, excepting those of cellular infiltrations, may all be regarded as belonging to one and the same category. However, the scientific demonstration of allergy as an etiological factor is extremely difficult and the problem requires some additional studies.
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尿道狹窄の臨床的並に組織学的研究

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