This section is from the book "Diseases Of The Intestines", by Max Einhorn. Also available from Amazon: Diseases Of The Intestines A Text-Book For Practitioners And Students Of Medicine.
Here in the acute form the mucosa of the appendix is swollen and reddened, the submucosa is engorged and filled with round cells. The follicles are distinctly swollen. The appendix appears swollen and more rigid, and its lumen is filled with thick yellowish contents, mostly mucus; sometimes the latter may be mixed with fecal matter. Occasionally there are fecal concretions. Often ecchymoses of the mucosa occur, leading sometimes to superficial defects (erosions). All these lesions may entirely disappear after the acute attack is over, and thus a perfect cure may be established. This, however, is possible only if there is no occlusion of the lumen of the appendix and the inflammatory products can be emptied into the caecum.
In the large majority of cases of catarrhal appendicitis the cure is not a perfect one and chronic appendicitis is the result. In this stage the mucosa of the appendix presents a slate-gray appearance. It is filled with accumulations of round cells; at the same time proliferation of connective tissue and occasionally blood pigment are found. The submucosa and muscularis may show no changes whatever, although as a rule they are hypertrophied. The latter condition is probably due to stricture of the lumen of the appendix and consecutive muscular (compensatory) hypertrophy. The chronic form of appendicitis, owing to suppurative processes of the mucous membrane, occasionally leads to a total destruction of the mucosa, and an obliteration of the lumen of the appendix. This condition is very similar to obliteration of the lumen due to the involution processes which have been mentioned above. The appendix then forms a solid membranous band of uniform thickness or with a few small protrusions. As a rule it is found embedded in peritonitic adhesions.
1 Riedel: " Ueber die Fruhoperation bei Appendicitis purulenta seu gangraenosa." Berl. klin. Wochenschr., 1899, Nos. 33 and 34.
Sometimes primary slight lesions of the appendix lead to complications, especially if a stricture is present. Thus an accumulation of secretion within the occluded appendicular cavity may take place and give rise to the formation of a cyst. Such cysts occur, varying in size from a cherry to a fist. Guttmann 1 observed a cyst of the appendix fourteen centimetres (five and a half inches) long and twenty-one centimetres (eight and a quarter inches) wide. The contents of such a cyst are either of a watery mucous character or gelatinous.
If ulceration takes place in the occluded appendicular cavity, it may give rise to the formation of a small abscess (py-appendix or empyema processus vermiformis). In these cases the purulent process may penetrate the wall of the appendix and lead to perforation. A timely operation in many instances prevents such an outcome.