Intraneural mucoid pseudocysts. A report of ten cases.

A mucoid pseudocyst of a peripheral nerve is a rare and benign tumour of controversial origin. We have reviewed ten patients with a mean follow-up of 3.2 years. The tumour affected the common peroneal nerve in eight and the ulnar nerve in two. The mean time between the onset of symptoms and diagnosis was 7.4 months (1.2 months to 2 years). On examination, there was pain in eight patients and swelling in seven. Motor deficit in the corresponding nerve territory was found in all. The diagnosis was usually confirmed by MRI. Treatment was always surgical. All the patients recovered, with a mean time to neurological recovery of 10.75 months. Recurrence was seen in only one patient and was treated successfully by further surgery. Our results are similar to those reported by other authors. A successful surgical outcome depends on early diagnosis before neurological damage has occurred.