Benign ancient schwannoma of the abdominal wall: an unwanted birthday present

Abstract

Background: There has been a recent growth in the use of whole body Computerised Tomography (CT) scans in the private sector as a screening test for asymptomatic disease. This is despite scant evidence to show any positive effect on morbidity or mortality. There has been concern raised over the possible harms of the test in terms of radiation exposure as well as the risk and anxiety of further investigation and treatment for the large numbers of benign lesions identified.

Case presentation: A healthy 64 year old lady received a privately funded whole body CT scan for her birthday which revealed an incidental mass in the right iliac fossa. This was investigated with further imaging and colonoscopy and as confident diagnosis could not be made, eventually excised. Histology demonstrated this to be a benign ancient schwannoma and we believe this to be the first reported case of an abdominal wall schwannoma in the English literature

Conclusions: Ancient schwannomas are rare tumours of the peripheral nerve sheaths more usually found in the head, neck and flexor surfaces of extremities. They are a subtype of classical schwannomas with a predominance of degenerative changes. Our case highlights the pitfalls of such screening tests in demonstrating benign disease and subjecting patients to what turns out to be unnecessary invasive investigation and treatment. It provides evidence as to the consequences of the large number of false positive results that are created by blind CT scanning of asymptomatic patients i.e. its tendency to detect pseudodiesease rather than affect survival rates. Should the number of scans increase there may be an unnecessary burden on NHS resources due to the large numbers of benign lesions picked up, that are then referred for further investigation.

Figure 1

Saggital section of CT Abdomen with Contrast. Well circumscribed RIF mass next to anterior abdominal wall.

Figure 2

Microscopic appearance of the lesion. Pronounced degenerative changes including myxoid stroma, haemorrhage, conspicuous blood vessels with hyaline thickening of walls and luminal thrombosis (H&E ×20)

Figure 3

Microscopic appearance of the lesion Focal marked nuclear pleomorphism, with isolated cells having bizarre hyperchromatic nuclei (H&E ×60)