Lesson of the Month - Chromogranin A expression correlates with tumour cell type and prognosis in signet ring cell carcinoma of the stomach

Aims: To investigate neuroendocrine (NE) differentiation in gastric signet ring cell carcinoma (SRCC) using chromogranin A (CgA) as an indicator of a well-differentiated NE phenotype and to determine its relationship to cell type, stage and prognosis. Methods and results: 102 SRCCs were categorized into five subtypes according to the predominant cell type in the World Health Organization classification. 38 cases (37.3%) showed focal or diffuse CgA positivity. The positive cells were mostly histiocytoid and eosinophilic SRCC cells and some were classical SRCC cells. Small cell and anaplastic-type SRCC cells were only rarely immunopositive. There was no significant relationship between CgA expression and the extent of invasion or presence of metastasis. However, a significant positive correlation existed between CgA positivity and favourable prognosis, with a tendency for greater positivity to be associated with better overall survival. Multivariate analysis showed expression of CgA to be an independent prognostic factor. Conclusions: CgA expression is restricted to certain tumour cell types and may help to predict prognosis in gastric SRCCs.