Extraosseous osteosarcoma arising from the small intestinal mesentery

Extraskeletal osteosarcoma (EOS) is a highly aggressive and exceedingly rare mesenchymal tumor. Due to the rare nature of the disease, the diagnosis can be difficult and is often confirmed only after diagnostic laparotomy and histopathology. We describe the clinical history, radiologic and histomorphologic presentation, and clinical management of a 61-year-old patient who presented with abdominal pain. Abdominal ultrasound and computerized tomography (CT) scan revealed a calcified intra-abdominal mass. Following an explorative laparotomy, histology showed a large extraosseous osteosarcoma of the small bowel mesentery. Therapy according to the Cooperative Sarcoma Study-96 (COSS-96) was commenced. Diagnosis, management, and outcome in the context of the current literature are discussed. To our knowledge, this is the first description of an extraosseous osteosarcomas in the small bowel mesentery in the literature.

Frequency of hereditary non-polyposis colorectal cancer among unselected patients with colorectal cancer in Germany

INTRODUCTION

Hereditary non-polyposis colorectal cancer (HNPCC) is a major form of familial colorectal cancer (CRC). It is diagnosed when either the Amsterdam criteria (AC) are fulfilled or mutations in one of the mismatch repair (MMR) genes have been identified. This project aims at estimating the proportion of HNPCC among unselected patients with CRC.

PATIENTS AND METHODS

During a period of 2 years, a total of 351 non-selected patients with CRC were registered prospectively. 92 patients met the Bethesda criteria (9 of them fulfilled the AC) and 259 did not. 348 tumours were examined for microsatellite instability (MSI) and expression of MMR proteins.

RESULTS

MSI-H and MSI-L were identified in 17 and 6%, respectively. Loss of MSH2 or MLH1 was found in 1.5 and 8.8%, respectively. Based on the results of tumour tissue analyses, 80 patients with MSI and/or loss of MSH2 or MLH1 expression were identified as candidates for germline mutation screening. DNA of 40/80 patients was available. These patients were screened for MSH2 and MLH1 mutations; 19/40 patients with MSI and normal MSH2 or MLH1 expression were screened for mutations in MSH6. Three patients had relevant MMR gene mutations and six variants of unknown functional relevance were detected.

CONCLUSIONS

After adjusting for the cases not evaluable for germline mutations, 1.7% of the CRC patients had HNPCC proven by molecular genetics.