Table 2: Immunohistochemical profile of neuroendocrine tumors.

IHCTypical carcinoidAtypical carcinoidPrimary lung small cell ca.Metastatic small cell ca.

CD56++++
Synaptophysin+++/−+/−
Chromogranin++−/+−/+
TTF-1−/+−/+Usually +Usually −
Ki-670–5%5–15%>20% (typically >60%)>20% (typically >60%)