Gastric stromal tumours

Previously named leiornyoma and leiomyosarcoma, the rather bland name of stromal tumour is now used because the biological behaviour of these tumours is unpredictable. Although it is reasonably straightforward for a pathologist to say that one particular lesions has a benign appearance and, at the other extreme, a tumour is highly malignant, there is a large number of tumours in which the distinction between benign and malignant is unclear. In general terms the larger the tumour and the greater mitotic activity the more likely it is to metastasise. Within the gastrointestinal tract the stomach is the commonest site for such turnouts.

The incidence of the condition is unclear as small stromal tumours of the stomach are probably quite common and remain unnoticed. Clinically obvious tumours are considerably less common than gastric cancer. The aetiology is unknown.

The only way that many stromal tumours are recognised is either that the mucosa overlying the tumour ulcerates (Fig. 51.26) leading to bleeding or that they are noticed incidentally at endoscopy. Because the mucosa overlying the tumour is normal, endoscopic biopsy can be uninformative unless the tumour has ulcerated. The appearance on barium meal is usually typical. Larger tumours present with nonspecific gastric symptoms and in many instances may initially be thought to be gastric cancer.

As the biological behaviour is difficult to predict the best guide is to consider the size of the tumour. Smaller tumours can be treated by wedge excision but larger ones require a gastrectorny. By their nature these tumours spread via the blood, and lymphatic metastases are relatively uncommon.

Common sites of spread include the liver, lungs and bone. Surgery is the only treatment modality that can cure the disease; adjuvant chemotherapy has not been shown to be beneficial. These tumours sometimes respond to systemic chemotherapy, but this is palliative.