Internal piles are best divided, according to Allingham,1 into the three following varieties:

1. Capillary Piles

These present small, florid, raspberry-looking tumors or rather vascular areas upon the mucous membrane, having a granular spongy surface and bleeding on the slightest touch; they are often situated rather high in the bowel; in structure they consist almost entirely of hypertrophic capillary vessels and spongy connective tissue. They resemble arterial naevi very closely, indeed, in their microscopical structure, except that they are covered externally by a very much thinner membrane and consequently are readily made to bleed.

2. Arterial Piles

These appear as tumors varying in size, sessile or somewhat pedunculated, attaining sometimes very considerable dimensions, glistening or slightly villous on their surface, slippery to the touch, hard and vascular with an artery often as large as the radial entering their upper part. When they are villous on their surface, they bleed very freely and for some reason or other have formed and grown very rapidly. On dissecting one of these tumors one will find that it consists of numerous arteries and veins frequently anastomosing, tortuous, and sometimes dilated into pouches, and of a stroma of cell growth and connective tissue, the latter most abundant.

1 William Allingham and Herbert W. Allingham: "The Diagnosis and Treatment of Diseases of the Rectum. " London, 1896, p. 113.

3. Venous Piles

In these the venous system predominates. The tumors are often very large and are sometimes the size of a hen's egg. They are bluish or livid in color. The surface may be smooth and shiny or pseudocutaneous.

External and internal piles often present themselves as nodules situated closely to each other and sometimes coalescing; thus larger tumors arise. In these hemorrhoidal varices important structural changes frequently take place. While at first soft, they may grow quite hard by the formation of blood clots or by a process of calcification. Inflammatory processes in the neighboring tissue have a tendency to increase their size and to make them more firm.

Internal piles are often pushed downward during the act of defecation. In this manner the mucous membrane of the base of the tumor is subjected to greater traction, and thus ultimately a pedicle is formed. Such nodules provided with more or less long pedicles and situated near the internal sphincter very frequently slip out from the anus at each defecation. When, however, they are not especially large, they spontaneously return into the rectum after defecation is finished. If they are of considerable size, it sometimes happens that they become incarcerated by the external sphincter, and if not carefully replaced, inflammation may develop and give rise to intense pains. Occasionally they may even become gangrenous and ultimately drop off. In some instances hemorrhoids undergo retrograde changes, become smaller, and even disappear entirely. Flaps of skin hanging near the anus and presenting a brownish color are often the remnants of previous piles. External piles sometimes give rise to the formation of warts and their surface assumes an uneven and wrinkled appearance. Internal hemorrhoids are often complicated by inflammatory processes of the neighboring tissues. Such processes give rise to the formation of ulcers, proctitis, and periproctitis.

In the latter instance an abscess may be formed, which may open either externally or internally, sometimes both ways. Thus a complete rectal fistula originates.

In internal hemorrhoids the mucous membrane of the rectum almost always exhibits the signs of a chronic catarrh. Its surface is swollen, succulent, and often covered with a thick layer of mucus. Occasionally there may be some pus. The proctitis accompanying piles may be either the cause or the sequel of the latter; sometimes, however, both may be due to some other factor.