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Massive Osteolytic Pseudogout of the Ligamentum Flavum 2005

General Spine

Abbie J Cluver, M.D.
Timothy Smith , M.D., Non ASSR Member
Jayne Seekins , M.D., Non ASSR Member
Christopher Moses , M.D., Non ASSR Member
Nada Besenski , M.D. Ph.D., Non ASSR Member
Zoran Rumboldt , M.D., ASSR Member

Excerpta

A 66-year-old man with history of hyperuricemia and multiple gout flare-ups in both feet presented with complaints of back pain radiating to the right chest, unsteady gait, and intermittent burning sensation in both feet, worse on the right. There were no bowel or bladder symptoms. The physical examination revealed mild ataxia and posterior column deficits with normal strength in the upper and lower extremities and normal deep tendon reflexes. There was a sensory level deficit consistent with a mid-thoracic lesion.
Radiographs of the thoracic spine demonstrated effacement of the T6 pedicle on the right (Image 1). MR imaging showed a mass of low T1 and T2 signal (Images 2 and 3) with homogenous contrast enhancement that involved the right side of T6 vertebral body with extension into enlarged right pedicle and transverse process and facet joint. An extradural intracanalicular portion of the mass that was compressing the spinal cord at T5-6 level (Images 2 and 3). There was also involvement of the paraspinal muscles and of the right sixth rib. The findings were thought to be consistent with an invasive lesion, likely a metastatic tumor.
T5 and T6 laminectomies were performed followed by excision of the right-sided intracanalicular extradural portion of the lesion at T6 that measured 4.3x3.5x1.0 cm. Intraoperative frozen specimens confirmed that the lesion was caused by calcium pyrophosphate dihydrate (CPPD) deposition disease with involvement of the ligamentum flavum, which is better seen on permanent slides (Image 4). The excised specimen also revealed characteristic birefringent crystals on polarized-light microscopy. The diagnosis of pseudogout was made and further dissection of the soft tissue mass from the facet joint was discontinued. The patient did well post-operatively and was discharged two days following surgery.

CPPD deposition disease or pseudogout is the most common crystalline arthropathy and can manifest in many clinical forms. The presentations can range from asymptomatic to severe pain with marked joint and bone destruction. CPPD crystals can deposit in fibrocartilage, hyaline cartilage and within other soft tissues, mimicking gout, septic joints, and other arthropathies. Pseudogout of the spine is often asymptomatic, but it may cause vertebral body destruction, severe sclerosis of the bone and disc space narrowing. Deposition of CPPD crystals into the ligamentum flavum and posterior longitudinal ligament is a rare but known cause of spinal cord compression and myelopathy of insidiouds onset. The involved ligament is characteristically thickened, of low to intermediate signal on both T1 and T2-weighted MR images, characteristically calcified on CT, due to massive focal deposition of CPPD crystals. We are, however, not aware of any described cases where CPPD crystal deposits in the ligamentum flavum caused frank lytic lesions of the adjacent bone with extension into the soft tissues, simulating an aggressive neoplasm.

References

1. Steinbach L. Calcium pyrophosphate dihydrate and calcium hydroxyapatite crystal deposition diseases: imaging perspectives. Radiol Clin N Am 2004;42:185-205

2. Muthukumar N, Karuppaswamy U. Tumoral calcium pyrophosphate dihydrate deposition disease of the ligamentum flavum. Neurosurgery 2003;53:103-8

Images

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