Goblet cell carcinoids of the appendix: Tumor biology, mutations and management strategies

Table 1 Immunomarkers and mutations for appendiceal goblet cell carcinoids, typical neuroendocrine tumors and adenocarcinoma

Markers	Goblet cell carcinoid	Typical carcinoid	Adenocarcinoma
CEA	+	-	+
CK7	+	-	+
CK20	+	-	+
CDX2	+	-	+
CD56	+/-	++	-
CAM5.2	+	-	+
Synaptophysin	+/-	++	-
Chromogranin A	+/-	++	-
Β-Catenin (nuclear)	-	-	+
p53	+/-	-	++
Ki67%	+/-	+/-	++
MUC1	-	-	++
MUC2	++	-	+/-
E-cadherin expression	N	N	U
MATH-1 expression	+	+	-
KRAS mutation	-	-	+
SMAD4 mutation	-	-	+
Notch signaling inhibition	U	+	-
MMR (MSH2, MSH6, MLH1, PMS2)	-	-	+/-

(+): Present; (-): Absent; (+/-): Present sometimes. CEA: Carcinoembryonic antigen; CK: Cytokeratin; CDX2: Caudal type homeobox transcription factor 2; CD56: Neural cell adhesion molecule; CAM 5.2: Antibody against CK8; p53: Tumor protein 53; Ki-67: Cellular proliferative marker; MUC: Mucin; Math-1: Protein atonal homolog 1 (a basic helix-loop-helix family of transcription factors); KRAS: V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog; SMAD4: Mothers against decapentaplegic homolog 4, transcription factors in the TGF pathway; MMR: Mismatch repair genes; N: Normal expression; U: Unknown.