Archives of Surgical Oncology

Introduction: Gastrointestinal Stromal Tumor (GIST), now the most common mesenchymal tumor of the Gastrointestinal Tract (GIT), spans a clinical spectrum from benign to malignant. It has been frequently studied, especially with regard to its successful targeted therapy using imatinib mesylate. Approximately 70-80% of GISTs have gain of function mutation of the KIT gene. The aim of the study is to describe spectrum of clinical presentation and histomorphologic characteristics in classic GIST with CD117 immunostaining in a tertiary care hospital from north east India. Design: This is a descriptive cross sectional study of cases encountered over one-year period. Cases included after histomorphology and immunohistochemistry staining with CD117.
Results: A total of 10 cases of GIST like histomorphology were studied and 6 were confirmed as GIST and included in the study. Four were males and two females with age ranged from 32 to 55 years. The cases had variable clinical presentations with abdominal pain and lump, melena and bleeding per rectum. Two of the cases were located in the stomach, one in the duodenum involving the periampullary area, one each in the ileocaecal region, transverse colon and rectum. Most of the cases grossly presented as a polypoidal growth. Four of the cases showed typical spindle cell morphology composed of interlacing bundles of uniform spindle shaped cells. One had a mixed morphology with features of both spindle cell and epithelioid pattern and one case mostly epithelioid type. Two cases showed intense immunoreactivity for CD117 in 90% of the tumour cells, three cases showed immunoreactivity for CD117 in 70-80% and in one case 50%. The management by surgical resections followed by 6 months imatinib mesylate treatment of 5 cases in the study had been showing good response for last two years.
Conclusion: The molecular phenotype is an important consideration in the treatment of patients from prognostic point of view. Those with mutations in KIT or PDGFRA often respond to the tyrosine kinase inhibitor imatinib in contrast, tumors without these mutations are generally resistant. So a uniform category of cases with cKIT mutation may be helpful to study treatment outcome besides standard predictor of biologic behavior. It would be interesting to see whether mutation guided diagnosis has any bigger role in prognosis of classic GIST in future studies involving larger sample size.

Cetuximab and panitumumab are monoclonal antibodies directed against the Epidermal Growth Factor Receptor (EGFR) which are now standard treatments for RAS Wild Type (WT) metastatic Colorectal Cancer (CRC), with efficacy in all lines of therapy. The evolution of the use of the EGFR-Inhibitors (EGFR-I) is the landmark journey of the application of a predictive marker and its translation into clinical utility. Here we describe how the evaluation of EGFR-I in patients with the resistant biomarker, i.e., RAS mutant, led to clinical suspicion that the G13D subset of mutated tumours may in fact be an exception. The hypothesis, raised from preclinical data, then retrospective analysis of trial outcomes, was subsequently prospectively tested by our group in a randomised clinical trial (RCT; the ICECREAM study) which unfortunately did not reveal that this particular mutation conferred sensitivity to EGFRI. The investigation of EGFR-I in KRAS G13D mutated metastatic CRC is a good example of the ability of international collaboration to perform RCTs even in rare molecular subtypes, as well as confirming the role of prospective clinical trial evaluation of hypotheses raised by unplanned subgroup analyses.

We report a case of benign fibrous Histiocytoma of the left tenth rib in a 40-year-old man. CT revealed an expanding lesion with calcification. An open biopsy of the lesion was performed and subsequently wide surgical resection of the left 10th rib was performed. Histological diagnosis was consistent with benign fibrous Histiocytoma of the rib.