The secondary inflammation is less conspicuous than it is in the diarthrodial substance, but there is a similar proliferation of embry onal cells that insinuate themselves among the fibrous elements of the synovial membrane, and bud out into little adventitious growths that sometimes undergo fatty degeneration.
Outside of the joints the deposits of urates may occur in many different structures of the body, but everywhere the process is the same; it follows the same course and is accompanied by the same sec ondary events. In the neighborhood of the affected joints, especially those of the feet and bands, the periosteum, the ligaments, and other fibrous tissues become incrusted with uric-acid salts, adding to the deformity and bulk of the tophi that form upon the joints themselves. The tendinous sheaths also become similarly involved, especially those of the deep and superficial flexors of the fingers, and of the pe roneal muscles and the tendo Achillis.
The various bursae are very generally invaded. Their cavities are greatly distended, and are occupied with a more or less ropy or semi solid liquid that exhibits every stage of mixture with uric salts. Sometimes their contents are stained with exuded blood, or are semi purulent from infection with pyogenic bacteria.
In their order of invasion the bursm upon the great toe and the metatarsal joints stand first; then follow those about the heel, the olecranon, and the knee. It is not usual to find evidences of disease in the bursce elsewhere.
It is in these inflamed bursa that is started the infective process that sometimes extends to the adjacent articulation, and results in pur ulent inflammation and complete destruction of the infected joint. It is not an uncommon thing in old cases of gout to be able to trace this process through all its stage's, from incipient bursal inflamma tion, through perforation of the articular capsule, to final suppuration mad ulceration of the infiltrated and incrusted tissues.
Another favorite place for a deposit of uric salts is in the sub cutaneous connective tissue. Here they accumulate in patches under the skin, sometimes following the course of a tendon or muscle, usually movable, though more or less thoroughly adherent to the under surface of the skin. In such cases, the meshes of the deep layer, the Malpighian network, become infiltrated with urates which accu mulate in little islets that are separated by fibrous bands.
The nutrition of the skin is necessarily hindered by this incrusta tion, and the integument becomes dry, earthy, and variable in thick ness. Some observers have thought that the process began in the sudoriparous glands, but analogy seems to contradict this view, since the glandular periphery is rich in capillary vessels, and infiltra tions elsewhere affect non-vascular tissues by preference. In ad vanced cases the skin becomes inflamed, ulceration takes place, and there is established an obstinate sore from the surface of which ex udes a mixture of blood and pus and uratic salts. In this way the integument may be extensively undermined, and fistulous passages opening into the joints may be excavated.
Small cutaneous tophi are frequently encountered upon different regions of the body, and they can be often recognized at an early stage of gout, even before the joints have been invaded. They have been carefully studied by Charcot and by Garrod who found them in nearly half his cases. They are usually of the size of a grain of wheat, but they sometimes reach the dimensions of a pea. They are exceedingly persistent, and they may excite the processes of in flammation and ulceration in the surrounding tissue like tophaceous concretions elsewhere. Their favorite seat is iu the external ear, along the helix, or in the fissure that separates the helix from the anti-helix—less frequently in the anti-helix or upon the inner surface of the concha.
Somewhat similar concretions are to be found in the skin upon the palmar surfaces of the fingers. Ulceration followed by formation of indelible scars is a common event.
Other cutaneous deposits are occasionally discovered in the eyelids, in the alp of the nose, and upon the cheeks, in the skin that covers the ulnae border of the forearm, and the internal aspect of the tibia. Sometimes concretions of various size are found in the integument, or in the subcutaneous areolar tissue of the glans penis or of the cavern ous portion of the organ. Occasionally they exist in the deep tissues of the cavernous substance itself.
It is worthy of note that wherever these abarticular tophi are found, they are always related to the connective fibrous elements of the affected structure. Everywhere the parenchymatous, muscular, and glandular tissues escape, while the fibrous elements attract to themselves the infiltrating orates.