Table 2: Immunohistochemical profile of neuroendocrine tumors.

IHC Typical carcinoid Atypical carcinoid Primary lung small cell ca. Metastatic small cell ca. CD56 + + + + Synaptophysin + + +/− +/− Chromogranin + + −/+ −/+ TTF-1 −/+ −/+ Usually + Usually − Ki-67 0–5% 5–15% >20% (typically >60%) >20% (typically >60%)