Chondromas springing from the pelvic bones usually arise in the region of the sacro-iliac joint; they project into the pelvis and press on the bladder and rectum, and on the sciatic and obturator nerves; sometimes also on the iliac veins, causing œdema of the legs. They are liable to take on malignant characters, and rarely lend themselves to complete removal by operation.
Fig. 145.—Radiogram of Myeloma of Humerus.
(Mr. J. W. Struthers' case.)
Fibroma is met with chiefly as a periosteal growth in relation to the mouth and pharynx, the simple epulis of the alveolar margin and the naso-pharyngeal polypus being the most common examples. We have met with a fibroma in the interior of the lower end of the femur of an adult, causing expansion of the bone with decided increase in girth and liability to pathological fracture; it is possible that this represents the cured stage of osteomyelitis fibrosa.
Myxoma, lipoma, and angioma of bone are all rare.
Myeloma.—The myeloid tumour, which is sometimes classified with the sarcomas, contains as its chief elements large giant cells, like those normally present in the marrow. On section these tumours present a brownish-red or chocolate colour, and, being highly vascular, are liable to hæmorrhages, and therefore also to pigmentation, and to the formation of blood cysts. Sometimes the arterial vessels are so dilated as to impart to the tumour an aneurysmal pulsation and bruit. The enlargement or “expansion” of the bone results in the cortex being represented by a thin shell of bone, which may crackle on pressure—parchment or egg-shell crackling.
The myeloma is most often met with between the ages of twenty-five and forty in the upper end of the tibia or lower end of the femur. It grows slowly and causes little pain, and may long escape recognition unless an examination is made with the X-rays. Although these tumours have been known to give rise to metastases, they are, as a rule, innocent and are to be treated as such. When located in the shaft of a long bone, pathological fracture is liable to occur.
Diagnosis and X-ray Appearances of Myeloma.—The early diagnosis of myeloma is made with the aid of the X-rays: the typical appearance is that of a rounded or oval clear area bounded by a shell of bone of diminishing thickness ([Fig. 145]). The inflammatory lesions at the ends of the long bones—tubercle, syphilitic gumma, and Brodie's abscess, that resemble myeloma, are all attended with the formation of new bone in greater or lesser amount. The myeloma is also to be diagnosed from chondroma, from sarcoma, and from osteomyelitis fibrosa cystica.