A 32-year-old female presented to the local hospital with history of anorexia, nausea, heartburn, fatigue, fever and weight loss (15 kg over 5 months). She denied any history of vomiting or change in bowel habits. Her investigations revealed anaemia (haemoglobin 7.7 g%). An upper GI endoscopy revealed chronic active gastritis with positive helicobacter pylori. Computerized tomography (CT) scan of the abdomen showed a mass in the stomach (Figure 1A) and hence was referred for further management. On examination she had a fever of 38 C and sinus tachycardia (120 beats/min). She also looked pale and emaciated, but there was no jaundice or lymphadenopathy. Abdominal examination revealed fullness in the left upper quadrant with tenderness on deep palpation.
Blood tests revealed iron deficiency anaemia (haemoglobin 7 g%) and hypoalbuminaemia (17 g/L; normal 34-50). Repeated upper GI endoscopy showed a mass occupying the proximal part of the stomach with 2 satellite lesions (Figure 1B). Biopsy of the lesion confirmed a low grade spindle/epitheloid cell tumor, probably of neural origin; gastric autonomic nerve tumor (GANT). Endoscopic ultrasound (EUS) revealed a gastric mass arising from the mucosa and submucosa with perigastric, and splenic lymph nodes. Biopsy from the lymph node was taken, but was inconclusive.
As part of preoperative preparation, total parenteral nutrition was started and two units of blood were transfused. She underwent exploratory laparotomy which showed a large fundal tumor infiltrating the hilum of the spleen and tail of pancreas with multiple perigastric lymph nodes. However, there were no free peritoneal fluid, peritoneal nodules or visible distant visceral metastasis. An en-block total gastrectomy, splenectomy and distal pancreatectomy was performed (Figure 2A, 2B) with Roux-en-Y oesophago-jejunal anastmosis. On postoperative day (POD) 6, the contrast swallow showed no leak, the patient was fed and discharged home on POD 7.
Histology of the specimen showed a heterogeneous multifocal malignant spindle cell/epithelioid cell tumor exhibiting variable patterns ranging from low grade sclerostic spindle cell areas to high grade epithelioid cell areas/nodules with high cellularity, geographical/palisading necrosis (Figure 3A) and frequent mitoses (Mitotic rate is 40/10 HPF). The tumor cells show rhabdoid morphology and in areas it shows fascicular arrangement with neural like areas. The tumor arises from the gastric fundus and invades throughout the gastric mucosa, submucosa, and muscle layer involving the subserosal fat and surrounding large serosal blood vessels and abutting the splenic capsule. All the harvested perigastric lymph nodes were reactive and negative for metastatic disease (0/6). All surgical resection margins were free of tumor which tethered the splenic capsule, without splenic or pancreatic parenchyma invasion. The two satellite mucosal nodules show similar appearances to the main tumor. The background gastric tissue is unremarkable and negative for dysplasia. Immunohistochemical staining revealed focal positive staining with for Vimentin, CD34 (Figure 3B), and S100 (Figure 3C), but were negative for c-kit (CD117), DOG1, SMA, Desmin, HMB45, ALK1, EMA, Pancytokeratin and NSE. Ki 67 was variable ranging from 10% to 70%. The histological immunohistologic findings (Figure 3C, 3D) are consistent with a gastrointestinal autonomic nerve tumor which represents a phenotypic variant of gastrointestinal stromal tumor.
She presented 2 months later, with mild dysphagia. Gastroscopy was advised to exclude an anastomotic stricture but she refused. Therefore, a CT scan with oral contrast was performed and showed a newly developed hypo-attenuating lesion at segment IVb (1.7x1.4 cm) consistent with hepatic metastasis. There was also a left chest solitary metastasis (Figure 4A) and an enlarged necrotic lymph node in the hepato-gastric ligament. A PET/CT 18F-FDP whole body scan showed FDG-avid pulmonary, upper abdominal, hepatic, adrenal, bony and muscular metastases (Figure 4B, 4C). She presented again 3-month later with a pathological fracture of the left humerus. Resection biopsy of the bone lesion revealed metastatic GANT invading bone and skeletal muscle tissue.
Her clinical condition deteriorated 3 months later and was admitted for palliative care management. She was later lost to follow-up and presumed dead.
CT scan showing the lung metastatic lesion.