A 63 year old man presented to his general practioner complaining of a stinging sensation on the left side of his abdomen without evidence of a skin rash. Six months later he developed a left sided abdominal swelling (figure) which enlarged with increasing intra-abdominal pressure. On examination he had an area of reduced muscle tone with bulging of abdominal contents. Cutaneous sensation over the pseudohernia was reduced, with a surrounding band of hyperaesthesia. Routine blood testing led to the discovery of diabetes mellitus. Abdominal ultrasound and MRI of the thoracolumbar spine were normal. Electromyography disclosed denervation of the left paraspinal muscles from T6 to T10 myotomes. The pseudohernia persisted for 1 year before gradually resolving.

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 Painful truncal radiculoneuropathies are a recognised complication of diabetes, unrelated to duration of disease and, as in this case, may be the presenting feature. They usually remit without recurrence within 18 months of onset. Diabetic truncal neuropathies leading to abdominal bulging have been described1 but are rare.