Primary leiomyosarcoma of the pancreas: report of a case treated by local excision and review of the literature

Abstract

Background: First described by Ross in 1951, primary pancreatic leiomyosarcoma is a rare mesenchymal tumour of the pancreas, with nonspecific clinical and radiological features and a poor prognosis, if unresectable.

Case report: A 60-year-old woman presented with abdominal pain. Magnetic resonance imaging (MRI) and computed tomography (CT) scan detected a dishomogeneous egg-shaped 8-cm mass, arising from the pancreatic head, with duodenal compression, without dilation of the Wirsung duct. (18)F-FDG positron-emission tomography (PET)-CT showed a moderate tracer uptake, and the endoscopic ultrasound (US) showed a hypoechoic lesion, arising from the duodenal wall, suspected to be a gastrointestinal stromal tumour (GIST). CEA, CA19-9, NSE, and chromogranin A were normal. At the surgical exploration, a 10-cm mass, adherent to the anterior aspect of the pancreatic head, was found. The lesion was easily separable from the duodenal wall and was totally excised. The frozen intraoperative examination showed a mesenchymal tumour, with spindle-shaped cells, suggesting that a GIST diagnosis was likely. Postoperative course was uneventful. Histology and immunohistochemistry demonstrated a well-differentiated leiomyosarcoma, with five to six mitotic counts per 10 high-power field (HPF) and proliferative index (MIB-1) 10 % (grade 2 according to Federation Nationale des Centres de Lutte Contre le Cancer (FNCLCC)), with positive smooth muscle actin, desmin, and caldesmon but negative CD117 (c-kit) and S-100. The patient is alive and asymptomatic 19 months after surgery, without evidences of disease.

Conclusions: In the English literature, only 44 cases of primary pancreatic leiomyosarcoma have been reported. If a pancreatic mass suspected for primary pancreatic leiomyosarcoma has no adjacent organ/vessel invasion or distant metastases, surgical resection is the therapy of choice.

Keywords: Leiomyosarcoma; Mesenchymal tumour; Pancreas; Pancreatic tumour; Sarcoma.

Fig. 1

Pre-operative imaging. MRI scan: the dishomogeneous mass, arising from the pancreatic head (a). CT scan: no evidence of invasion of the surrounding tissues; CT venous phase: duodenal compression on the third duodenal part. (b) CT arterial phase: mass arising from the pancreatic head (c). ¹⁸F-FDG-PET-CT: moderate tracer uptake by the pancreatic lesion (d)

Fig. 2

Intraoperative findings. The mass was adherent to the anterior surface of the pancreatic head, and it was easily dissociable from the duodenal wall (a). The 10-cm mass was totally excised. Macroscopically, it had a smooth and polylobulated surface (b)

Fig. 3

Histology and immunohistochemical analysis. Haematoxylin-eosin stain (original magnification ×50) (a). Mib1 (proliferative index) (b). Strong immunoreactivity to smooth muscle actin (c). No immunoreactivity to CD117 (c-kit) (d)

Fig. 4

Postoperative imaging. Thorax-abdominal CT scan: normal appearance of the pancreatico-duodenal-biliary region, without any signs of liver or lung involvement