Alkaptonuria-an atypical case: multi-modality imaging review.

Area of Science:

• Biochemistry and Genetics
• Metabolic Disorders
• Skeletal Degeneration

Background:

• Alkaptonuria (AKU) is a rare inherited metabolic disorder caused by mutations in the homogentisic acid oxidase (HGO) gene.
• HGO deficiency leads to the accumulation of homogentisic acid (HGA) in blood and urine.
• HGA deposition causes ochronosis, a condition characterized by tissue pigmentation and degeneration, typically affecting the spine.

Observation:

• Ochronosis commonly affects the dorsolumbar spine, usually sparing the cervical spine and sacroiliac joints.
• This case presents isolated ochronosis with significant, previously undescribed, degenerative changes in the cervical spine.
• The observation includes extensive cervical vertebral fusion, a finding not previously documented in the literature for this condition.

Findings:

• The study highlights a unique presentation of ochronosis with severe cervical spine involvement.
• Co-existent degenerative changes and vertebral fusion in the cervical spine are reported in this isolated case.
• This expands the spectrum of skeletal manifestations associated with alkaptonuria and ochronosis.

Implications:

• Findings suggest that alkaptonuria may present with more extensive and varied spinal pathology than previously recognized.
• This case underscores the importance of considering cervical spine evaluation in patients with ochronosis.
• Further research is warranted to understand the mechanisms behind isolated cervical spine involvement in AKU.