Multiple Vertebral Osteonecroses (Kümmell's Disease) After 10 Years on Denosumab: Is Osteocyte Apoptosis to Blame?

We report here a case of multiple vertebral osteonecroses with intrasomatic gaseous dissection (Kümmell's disease) occurring 1 year after the end of a 10-year course of denosumab treatment for osteoporosis without fractures. Histomorphometry and bone remodeling markers revealed major bone resorption and the persistence of an inhibition of bone formation. The presence of multiple empty lacunae in the bone provided evidence for high levels of osteocyte apoptosis. Osteocytes direct bone resorption (via the RANK/RANK-L/osteoprotegerin system) and formation (Wnt system, with SOST and DKK1) pathways. The vertebral osteonecrosis in our case may, therefore, have resulted from osteocyte apoptosis, decompensated by the sudden reactivation of bone remodeling after the cessation of denosumab treatment.

Contribution of 18-FDG PET/CT to brown tumor detection in a patient with primary hyperparathyroidism.

We report the case of a patient who presented with multiple brown tumors as the inaugural manifestation of primary hyperparathyroidism. Tc-99m hexakis methoxyisobutylisonitrile (99mTc-MIBI) scintigraphy demonstrated increased radiotracer uptake by the bone lesions. The patient was a 65-year-old male who sought advice for a swelling on his right shin. An osteolytic lesion was visible on the radiograph. A bone biopsy showed a benign tumor containing abundant osteoclastic cells. Laboratory abnormalities included hypercalcemia (3.63mmol/L with 1.91mmol/L ionized calcium), hypophosphatemia (0.38mmol/L), and parathyroid hormone elevation (880.8pg/mL; N: 10-70). Serum 25-OH Vitamin D level was lower than 4ng/mL (N: 30-60). An 18-FDG PET/CT scan identified numerous high-uptake bone lesions. By 99mTc-MIBI scintigraphy, a large high-uptake mass was seen in the left parathyroid gland, as well as high-uptake lesions throughout the skeleton, which were less numerous than those seen by 18-FDG PET/CT. Ultrasonography of the neck visualized a mass consistent with an adenoma in the left parathyroid gland. Brown tumors are bone lesions whose diagnosis should be considered in patients with clinical and laboratory evidence of hyperparathyroidism, once a malignant disease is ruled out. Our case report suggests that 18-FDG PET/CT may be more sensitive than whole-body 99mTc-MIBI scintigraphy in detecting brown tumors.