Amyloidoma, an Unusual Cause of Fracture

We report a case of a spontaneous hip fracture in a context of dysglobulinemia. The bone histologic examination found amyloidoma. Amyloidoma is an overload pathology and an unusual cause of fracture. In most of the cases, it is associated with myeloma and the difference between bone invasion of myeloma and amyloidoma in an osteolytic radiographic picture is not easy but is of importance because prognosis and treatment may be totally different. Thus, in the context of dysglobulinemia, one must keep in mind that spontaneous bone fracture may be due to amyloidoma with another prognosis. 1. Introduction Amyloidoma is an uncommon cause of bone fragility. It occurs in the context of dysglobulinemia and the difference between amyloidoma and myeloma is difficult but is important. 2. Case We report the clinical story of an 87-year-old man who was hospitalized for a right hip fracture without high energy trauma. He was known, but not followed up, for a kappa light chain monoclonal gammopathy diagnosed 7 years ago. He had no inflammatory syndrome (CRP 10？mg/dL and ESR 25？mm) and no hypercalcemia ( 2, 57？mmol/L). The electrophoresis was characterized by an hypogammaglobulinemia and the presence of kappa light chain. The myelogram showed 9% of kappa light chain monoclonal plasmocytes. The Bence Jones proteinuria was positive. He underwent a hip arthroplasty and the histological examination of the femoral head found multifocal non-AA amyloid deposits, with osteolysis and a pseudotumoral aspect (amyloidoma). A biopsy of accessory salivary glands found non-AA amyloid deposits too. The radiographic exam (Figure 1) at the time of the fracture diagnosis showed geodes surrounded by area of osteosclerosis corresponding to focal deposits of amyloid. The extension statement showed only other geodes in the left hip (Figure 2). Six months later, he suffered from a contralateral hip fracture probably secondary to amyloidosis too. Figure 1: Radiographic aspect of hip fracture Garden 3 secondary to amyloidoma. Figure 2: Geode of the left hip probably secondary to amyloidoma. 3. Discussion This is the second observation of hip fracture secondary to amyloidoma [1]. Amyloidoma is an unusual cause of fracture. Amyloidosis is an overload pathology characterized by extra cellular deposits of amyloid substance. The osteoarticular involvement represented by amyloidoma, amyloid arthropathy [2], and amyloid polyarthritis [3] is rare. Few types of amyloidosis are responsible for these manifestations [4]: AL amyloidosis which is primary or associated with myeloma [5], β 2-microglobulin