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A6493 - Disseminated Skeletal Sarcoidosis Mimicking Malignant Metastasis
Author Block: A. Jacob, K. Granet, C. Patton; Internal Medicine, Monmouth Medical Center, Long Branch, NJ, United States.
Introduction: Sarcoidosis is a chronic inflammatory condition of unknown etiology most commonly involving lungs. Involvement of musculoskeletal system is reported only in 15-25% of cases and is mainly manifested as arthritis. Axial sarcoidosis is rarer and involves the vertebral bodies and the sacroiliac joints. It might mimic cancer metastasis, myeloma or conditions like Langerhans cell histiocytosis. Our case is an atypical presentation of a rare condition extrapulmonary axial sarcoidosis extensively involving the skeletal system without affecting any lung tissue.
Case Report: 53-year-old male presented with lower back pain after lifting a heavy box a week ago. He denied any bowel or bladder incontinence, or weakness of his extremities. Physical examination was unremarkable with no spinal tenderness or neurological deficits. Lumbosacral x-rays and nuclear whole-body bone scan were normal. MRI lumbar spine demonstrated increased signal density of the L4-5 vertebral disc, multiple disc herniation without cord compression. He had worsening of pain in his bilateral thighs and MRI lower extremity showed T2 hyperintense lesions throughout the bony pelvis and bilateral femurs which were suspicious of myeloma or metastatic disease. However, blood counts, liver, and renal function tests, PSA and serum protein electrophoresis were normal. PET-CT showed extensive osseous metastatic disease throughout cervical, thoracic and lumbar spine, pelvis and bilateral femur. No FDG accumulation was noted in the chest soft tissue and lungs. Bone biopsy of the lesion showed multiple noncaseating granulomata consistent with sarcoidosis. The patient was started on corticosteroids with resolution of symptoms and significant reduction of FDG avidness on repeat PET-CT. The final plan is to continue steroid at a lower dose with the addition of hydroxychloroquine as a steroid-sparing agent until disease resolution.
Discussion: Sarcoidosis of bone occurs in 1-13% of sarcoid patients and might be an early manifestation of the disease. Presence of bone lesion signify severe and chronic disorder and is seldom present without pulmonary involvement. Spinal disease is rarer with only case reports and series reported. The lesions present as lytic lesions on radiograph and are often misdiagnosed as malignancy and need histopathological confirmation. Complications include fractures, cord compression, and nerve impingements. Glucocorticoids are the first line of treatment. Our patient responded to corticosteroid therapy with remarkable changes on PET-CT. The case is also peculiar with an exclusive musculoskeletal disease with no lung involvement. Knowledge of the condition is necessary to help follow proper diagnostic and treatment protocol preventing progression and complications.