Image Quiz

A Lytic Lesion of the Metacarpal in a Twenty-eight-Year-Old Woman (continued)

Answer: Brown tumor.

Fig. 3-A	Fig. 3-B
Figs. 3-A and 3-B Photomicrographs of a specimen from the metacarpal lesion showing numerous osteoclastic giant cells. Considered alone, the histological appearance can be seen as a giant-cell reparative granuloma, but, in the clinical context of this patient, it is almost certainly a brown tumor of hyperparathyroidism. Fig. 3-A After staining with hematoxylin and eosin (×200). Fig. 3-B After staining with hematoxylin and eosin (×400). For larger view, click on image

Histologic examination revealed multinuclear giant cells adjacent to hemosiderin granules, consistent with a brown tumor (Figs. 3-A and 3-B). Oral calcitriol (0.5 µg daily) and elemental calcium (3 g daily) supplementation was commenced for two weeks until the serum vitamin-D levels and histopathologic evaluation were obtained. Three hundred thousand units of vitamin D was administered intramuscularly once. After discharge from the hospital, she was managed with ergocalciferol (1000 U daily) and oral calcium (1000 mg daily). Biochemical analysis performed three months later revealed a serum calcium level of 9.6 mg/dL (2.40 mmol/L), a phosphate level of 3.5 mg/dL (1.13 mmol/L), an alkaline phosphatase level of 156 IU/L, and a serum intact parathyroid hormone level of 78 pg/mL (80 ng/L). Over the next year, while maintaining the same dose of calcium and vitamin D, the patient had improvement in her level of energy and the radiographic changes of osteitis fibrosa cystica in the metacarpal and pubis regressed (Fig. 4). Serum calcium and phosphate levels were normal, but the serum parathyroid hormone level remained minimally elevated.

Fig. 4

Fig. 4 Radiograph of the right hand made after one year of vitamin-D treatment.

For larger view, click on image

Discussion

Brown tumors are locally destructive bone lesions caused by rapid osteoclastic bone resorption due to severe hyperparathyroidism. For years, brown tumors have been considered to be characteristic of primary hyperparathyroidism. However, brown tumors also have been reported to occur in patients with severe hyperparathyroidism secondary to chronic renal failure, especially those on long-term hemodialysis. Hypocalcemia, hyperphosphatemia, and vitamin-D deficiency are the basic characteristics of chronic renal failure associated with secondary hyperparathyroidism.

Osteomalacia is rare in developed countries, but it is still a problem in some areas of the world. Dietary deficiency of vitamin D and lack of exposure to sunlight are the main causes. Debilitated people living indoors, people living in high altitudes, individuals with malabsorption, and veiled women are at risk of a vitamin-D deficiency. The prevalence of vitamin-D deficiency in the Asian immigrant population in the United Kingdom has been reported to be as high as 24%. In a recent Australian study, 80% of eighty-two veiled or dark-skinned pregnant women were found to have a vitamin deficiency.

Reference

1. Erturk E, Keskin M, Ersoy C, Kaleli T, Imamoglu S, and Filiz G. Metacarpal brown tumor in secondary hyperparathyroidism due to vitamin-D deficiency. A case report. J Bone Joint Surg Am. 2005;87:1363-6.