Hypertrophic Pulmonary Osteo-Arthropathy.—This condition, which was described by Marie in 1890, is secondary to disease in the chest, such as chronic phthisis, empyema, bronchiectasis, or sarcoma of the lung. There is symmetrical enlargement and deformity of the hands and feet; the shafts of the bones are thickened, and the soft tissues of the terminal segments of the digits hypertrophied. The fingers come to resemble drum-sticks, and the thumb the clapper of a bell. The nails are convex, and incurved at their free ends, suggesting a resemblance to the beak of a parrot. There is also enlargement of the lower ends of the bones of the forearm and leg, and effusion into the wrist and ankle-joints. Skiagrams of the hands and feet show a deposit of new bone along the shafts of the phalanges.
Tumours of Bone
New growths which originate in the skeleton are spoken of as primary tumours; those which invade the bones, either by metastasis from other parts of the body or by spread from adjacent tissues, as secondary. A tumour of bone may grow from the cellular elements of the periosteum, the marrow, or the epiphysial cartilage.
Primary tumours are of the connective-tissue type, and are usually solitary, although certain forms, such as the chondroma, may be multiple from the outset.
Periosteal tumours are at first situated on one side of the bone, but as they grow they tend to surround it completely. Innocent periosteal tumours retain the outer fibrous layer as a capsule. Malignant tumours tend to perforate the periosteal capsule and invade the soft parts.
Central or medullary tumours as they increase in size replace the surrounding bone, and simultaneously new bone is formed on the surface; as this is in its turn absorbed, further bone is formed beneath the periosteum, so that in time the bone is increased in girth, and is said to be “expanded” by the growth in its interior.
Primary Tumours—Osteoma.—When the tumour projects from the surface of a bone it is called an exostosis. When growing from bones developed in membrane, such as the flat bones of the skull, it is usually dense like ivory, and the term ivory exostosis is employed. When derived from hyaline cartilage—for example, at the ends of the long bones—it is known as a cartilaginous exostosis. This is invested with a cap of cartilage from which it continues to grow until the skeleton attains maturity.
An exostosis forms a rounded or mushroom-shaped tumour of limited size, which may be either sessile or pedunculated, and its surface is smooth or nodulated ([Figs. 138] and [139]). A cartilaginous exostosis in the vicinity of a joint may be invested with a synovial sac or bursa—the so-called exostosis bursata. The bursa may be derived from the synovial membrane of the adjacent joint with which its cavity sometimes communicates, or it may be of adventitious origin; when it is the seat of bursitis and becomes distended with fluid, it may mask the underlying exostosis, which then requires a radiogram for its demonstration.
