Diagnosis of endoneural sciatic nerve invasion by uterine cervical epidermoid cancer using [¹⁸F]FDG-PET/CT

Excerpt

Three years after treatment, a 54-year-old woman with a history of uterine cervical epidermoid cancer experienced discomfort in her back associated with right-sided sciatica resistant to medications. MRI revealed a disc hernia (L5–S1) and the patient was referred to surgery with subsequent reduction in pain. One year later, she developed anaesthesia dolorosa and a complete motor deficit in the right sciatic nerve territory. MRI revealed diffuse swelling of the right sacral plexus and a tumoural origin—possibly lymphomatous—was considered. The high signal intensity of the pyramidal muscle observed on the T2-weighted sequence (a, arrows) was considered a consequence of muscle denervation. Whole-body [¹⁸F]FDG-PET/CT showed increased uptake in the right sciatic nerve and sacral plexus (b, arrowheads). SUV_max was 2.8. The nerve diameter was enlarged on the CT image (c, arrows). Fusion with CT (d) and MRI (e) demonstrated that [¹⁸F]FDG uptake was confined within the nerve sheath, homogeneously. An open surgical biopsy of the sciatic nerve revealed the presence of endoneural metastatic cells of epidermoid origin. …