Hereditary osteopetrosis of the rabbit. IV. Pathologic observations; general features.

The results of postmortem examination of cases of hereditary osteopetrosis of the rabbit together with histologic observations on organs and tissues other than the skeleton have been described. The principal findings were, first, those associated with the characteristic progressive anemia of the disease, such as extramedullary foci of hemopoietic tissue, lymphoid hyperplasia, and the occurrence of hemosiderin in the liver, spleen, and lymph nodes. There was a widespread tissue distribution of intense phosphatase staining and of fine calcium deposition, as would be expected in the circumstances of the profound skeletal abnormality (3). In advanced cases with established growth retardation, malnutrition, and deterioration, the tissues generally showed a decreased glycogen content. The large amount of parathyroid tissue found in both early and late cases suggested a state of hyperparathyroidism. Low serum calcium, high serum phosphorus and phosphatase levels (2), and a predominately osteoblastic reaction (3) were suggestive of hypoparathyroidism. The possibility that an involvement of the parathyroid glands was a basic or primary condition of the disease is discussed. Evidence of a disturbance of other endocrine glands was shown by the predominately acidophilic staining reaction of the colloid of the thyroid, an enlargement of the adrenals in which both cortex and medulla participated, and the tendency toward a basophilia of the anterior lobe of the pituitary. It was pointed out that before an explanation of the part played by the parathyroid glands in this disease could be made, other data, including particularly embryological studies, must be available. Similarly, an interpretation of other endocrine gland changes must await additional information.