Rectal adenocarcinoid with lymph node metastasis

We describe a case of a rare variant of a rectal carcinoid tumor that showed mucous gland differentiation accompanied by a lymph node metastasis with a histological appearance similar to that of the primary site. The tumor consisted of a typical argyrophilic carcinoid component and of goblet cell glands. The carcinoid component was positive for neuron-specific enolase, chromogranin A and synaptophysin. The goblet cells stained positively with periodic acid-Schiff (PAS) and alcian blue, and expressed carcinoembryonic antigen, but were negative for neuroendocrine markers. This case suggests that carcinoid tumor can differentiate towards mucus glands, which can also be found in the metastatic site.