Microvessel Density (Chalkley Method) in a Series of 79 Gastrointestinal Stromal Tumors

BACKGROUND: Evaluation of the MVD (modified Chalkley method) in a series of 79 cases of GISTs diagnosed by the Pathology Service at the HCPA (Hospital de Clinicas de Porto Alegre) from January 1993 to December 2009. METHODS: Seventy nine cases of GISTs were submitted to immunohistochemical analysis for CD31, an endothelial marker, to analyze MVD. Hot spots were identified for each case, and the mean numbers of stained blood vessels collected through Chalkley count, with the use of a 25 point grid, placed onto a scanned image. Images were analysed through an image analysis system. We used a cutoff of six vessels. RESULTS: Our series was composed of 42 males and 37 females and presented an average age of 58.9 years. GISTs were predominately located in the stomach (45.6%) followed by the small intestine (38.0%). Sixty seven GISTs (84.8%) showed an average of less than six vessels stained by CD31 (MVD) and 12 (15.2%) GISTs an average of more than six vessels. A statistically significant difference was observed between survival rate of patients having GISTs with MVD of ≤ 6 vessels (mean = 2.4, CI 95%: 1.67 - 3.17) and patients having GISTs with MVD of ≥ 6 vessels (mean = 2.4, CI 95%: 1.67 - 3.17), P = 0.001. No association for MVD was observed related to sex, age, histological type, risk category, location and metastasis. CONCLUSIONS: Seventy nine cases of GISTs diagnosed at a single center in South Brazil were studied for MVD (Chalkley method). There was a statistically significant difference between MVD and the survival rate for these patients. The use of Chalkley method in GISTs may be helpful to evaluate clinical outcome.