Lumbar Spine Pseudogout Mimicking Disc Prolapse and Radiculopathy: A Rare Case Report

Calcium Pyrophosphate Dihydrate (CPPD) deposition disease, also known as pseudogout, is a crystal-induced arthropathy that primarily affects larger, weight-bearing joints such as the knees, hips, and shoulders. CPPD can present with a wide spectrum of clinical manifestations, ranging from asymptomatic chondrocalcinosis to acute inflammatory arthritis. CPPD in the spine is rare and can lead to calcification of the ligamentum flavum, potentially causing spinal cord compression, myelopathy, and significant neurological impairment. The absence of chondrocalcinosis on imaging does not rule out the diagnosis of spinal CPPD. On microscopy, CPPD is characterised by rhomboid-shaped, positively birefringent crystals, in contrast to the needle-shaped, negatively birefringent crystals observed in gout. The present case report of a 78-year-old female highlights a rare and isolated clinical presentation of CPPD causing lumbar spine myelopathy, which was discovered incidentally on histopathology after spinal decompression and discectomy surgery. Although imaging modalities may raise suspicion for CPPD by revealing chondrocalcinosis, they often lack the specificity to differentiate it from other degenerative or inflammatory conditions. Histopathological analysis and polarised microscopic examination remain the cornerstones in diagnosing CPPD, even in atypical clinical presentations or ambiguous imaging findings. This underscores the importance of including pseudogout in the differential diagnosis of lumbar myelopathy, particularly in elderly patients, to provide early, targeted treatment and prevent severe irreversible neurological deficits.