Figure 719

Pseudofractures (Looser's transformation zones) at the margins of the scapula in a patient with oncogenic osteomalacia. Similar to the genetic X-linked hypophosphatemic rickets, a circulating phospha-turic factor is believed to be released by the tumor, causing phosphate wasting and reduced calcitriol formation by the kidney. Note the radiolucent ribbonlike decalcification extending into bone at a right angle to its axillary margin. Pseudofractures are pathogno-monic of osteomalacia with a low remodeling rate.

FIGURE 7-20 (see Color Plate)

Histologic appearance of trabecular bone from a patient with oncogenic osteomalacia. Undecalcified bone section with impaired mineralization and a wide osteoid (organic matrix) seam stained with von Kossa's stain is illustrated. Note the wide bands of osteoid around the mineralized bone. Absence of osteoblasts on the circumference of the trabecular bone portion indicates a low remodeling rate.

FIGURE 7-21 (see Color Plate)

Microscopic appearance of bone section from a patient with vitamin D deficiency caused by malabsorption. The bone section was stained with Masson trichrome stain. Hypophosphatemia and hypocalcemia were present. Note the trabecular bone consisting of very wide osteoid areas (red) characteristic of osteomalacia.

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