Endocrinology Fellow Advocate Christ Medical Center Oak Lawn, Illinois, United States
Introduction : Amyloidosis presenting as radiolytic bone lesions is a rare disease manifestation. It typically presents as an expansile lytic lesion most commonly in the skull and spine region. We present herein a patient with fragility fracture from amyloidosis successfully managed with Denosumab therapy. The diagnosis was established with a biopsy from a lytic lesion on the thoracic spine.
Case(s) Description : A 67-year-old female with past medical history of Type 2 Diabetes, Obesity, Hypertension, and Endometrial Adenocarcinoma presented with low back pain after lifting her dog. She was found to have a spontaneous T7 compression fracture. She denied any trauma or fall. She underwent kyphoplasty complicated by wound dehiscence requiring repeat surgery. Due to the compression fracture, patient was diagnosed with osteoporosis. Her DXA was in the osteopenic range with high Risk FRAX score requiring Denosumab therapy. She was also incidentally discovered to have mild left adrenal gland hyperplasia. Workup for Osteoporosis as well as adrenal incidentaloma with biochemical testing came back unremarkable including normal calcium level, renal function, 25 OH Vitamin D 42.4 (30-100 ng/dl), normal urine protein electrophoresis and adequate DHEAS. She had mildly abnormal cortisol after 1 mg dexamethasone suppression test; 1.9 (< 1.8 mcg/dl), normal late night salivary cortisol *2, Plasma metanephrines, and 24 hours urinary free cortisol. Tissue Transglutaminase Antibody was negative. After 2 years of Denosumab therapy, the previously demonstrated Osteopenia improved. She did not sustain further fractures despite having multiple falls. Later, the patient started complaining of a new lower back pain, MRI pelvis showed a subcentimeter enhancing foci in the sacral spine regions of S2 and S3 suspicious for metastatic disease. A follow up PET CT showed a hypermetabolic new lytic lesion in T3 consistent with metastasis for which she underwent CT-guided biopsy. The biopsy results showed a plasma cell neoplasm involving approximately 90% of the bone marrow space, light chain lambda restricted positive for amyloid deposition with Trichrome and Congo red stain. The patient is currently undergoing chemotherapy for further treatment of Amyloidosis.
Discussion : The etiology of Osteoporosis and Osteopenia can often be multifactorial. The guidelines for evaluation are a great resource. Determining a clear underlying etiology though may be challenging particularly when looking for a systemic illness as an etiology of secondary Osteoporosis. In our case, an amyloidoma was discovered on biopsy prior to its progression to disseminated amyloidosis or multiple myeloma. This was discovered on a new T3 spinal lytic lesion when the patient complained about a new back pain. This case suggests that amyloidosis should be kept on the differential of osteoporosis despite being rare. Patient has also probably a component of postmenopausal osteoporosis. She responded well to Denosumab therapy with no recurrent fractures.
