Endocrine Abstracts

Introduction: Pheochromocytoma and most abdominal paraganglioma (PPGL) can secrete catecholamines. In vitro and in vivo, catecholamines modulate bone remodeling by stimulating bone resorption. In patients with PPGL, four studies have previously demonstrated an increase of biological markers of bone resorption, a decreased of bone density and a higher prevalence of vertebral fractures. We report two patients with malignant abdominal secreting paraganglioma presenting with osteoporosis and altered bone microarchitecture.

Case reports: Patient 1, 43 years-old, was operated for a norepinephrine-producing SDHB abdominal paraganglioma causing malignant hypertension. One year after surgery, magnetic resonance imaging (MRI) diagnosed metastases in T7 and L1 with concordant high uptake in 123I-MIBG and ^{18<U>F-FDG PET/CT[/U>} imaging and additional multiple osteoporotic painful vertebral fractures outside the metastatic sites. A dual energy X ray absorptiometry (DEXA) showed lumbar (Tscore = −2.90) and left hip (Tscore = −2.70) osteoporosis. Patient 2, 35 years-old, had a norepinephrine and dopamine-producing SDHA paraganglioma with regional lymph nodes and liver metastases. DEXA revealed lumbar (Tscore = −3.10) and left hip (Tscore = −2.40) osteoporosis. A treatment by temozolomide and capecitabine was initiated. To evaluate bone structure, the patient underwent a high-resolution peripheral computed tomography (HR-pQCT) showing a moderate alteration of bone microarchitecture. At the right tibia, total density (Dtot) was measured at 275 mg HA/cm [normal for the age and the sex (n): 338 ± 51], trabecular bone density (Dtrab) at 173.3 (n: 199 ± 39), trabecular number (Tb.N) at 1.67 l/mm (n: 1.90 ± 0.33), trabecular thickness (Tb.Th) at 0.087 (0.09 ± 0.01). At the left radius, Dtot was measured at 311.4 mg HA/cm (346 ± 57), Dtrab at 179.9 (201 ± 35), Tb.N at 2 l/mm (1.97 ± 0.22), Tb.Th at 0.075 (0.09 ± 0.01). Catecholamine secretion was respectively 12-fold and 29-fold the normal values in these patients who had no other risk factors for osteoporosis than prolonged exposure to catecholamines.

Conclusion: Catecholamine excess can lead to secondary osteoporosis in secreting PPGL. We show here for the first time by the gold standard method, the HR-pQCT, an altered bone microarchitecture. Being aware of such complications is particularly important in malignant PPGL that may have progressive disease and higher catecholamine production contributing to more serious bone complications. Eventually, with bone metastasis present in approximately 70% of metastatic patients, the catecholamine-induced bone fragility can lead to fracture, pain and decreased quality of life as illustrated here. We also believe that osteoporosis should be sought in every patient with malignant PPGL.