Abstract

Background: Ki67, Bcl2 and CD117 are expressed significantly greater in high-grade Bronchopulmonary Neuroendocrine Tumors (BP-NETs). This study tries to evaluate the co-expression of these three markers in small Cell Neuroendocrine Tumors (SCNETs) and Typical Carcinoid Tumors (CTs).

Method: Formalin Fixed Paraffin Embedded (FFPE) blocks from the specimen repository of the Department of Pathology at Masih Daneshvari Hospital were evaluated. IHC stain was used to assess the expression of ki67, Bcl-2 and CD117 in 17 SCNETs and 19 cases of CTs. Staining percentage of neoplastic cells was multiplied by intensity of the stain to produce the Staining Index (SI). SI higher than 6 for Ki67 and 25 for both Bcl2 and CD117 were considered positive.

Result: Expression of ki67 and Bcl2 was significantly higher in SCNETs. CD117 expression and Bcl2/Ki67/ CD117 co-expression were not significantly different between SCNETs and CTs. Bcl2/Ki67 and CD117/Bcl2 but not ki67/CD117 were significantly higher in SCNETs (P< 0.05). CD117 was positive in 52.6% of CTs and 65% of SCNETs. Its positivity was not significantly greater in bronchial biopsies of SCNETs devoid of crush artifacts.

Conclusion: A statistically significant difference was documented in single and paired expression of Ki67 and Bcl-2 as well as co-expression of CD117/Bcl-2 which could assist in discriminating low versus high grade Bronchopulmonary neuroendocrine tumors; however, using CD117 expression for this purpose requires more investigation.