Thoracic endplate osteomyelitis/discitis - false positive FDG PET scan

Case contributed by Dr Chris O'Donnell

Presentation

Incidental right lung mass lesion for investigation. Thoracic back pain.

Patient Data

Age: 80 years
Gender: Male

FDG PET-CT for differentiation of the lung lesion

PET-CT shows an FDG avid mass in the right upper lobe of lung consistent with a primary lung malignancy. There is also a markedly avid focus in the mid thoracic spine, possibly a metastasis. MRI is recommended for confirmation.

Rather than a malignant mass, there are features typical of endplate osteomyelitis, i.e. a destructive process centered on the disc with secondary bone collapse and a large paravertebral cuff-like soft tissue mass containing fluid (rim enhancing) consistent with pus. Neutrophils utilize glucose at a similarly increased rate to malignant cells so they are highly FDG avid thus a potential false positive for malignancy.

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