Carcinoid Tumors of Digestive Organs: a Clinicopathologic Study of 13 Cases

The author investigated clinicopathologic features of 13 cases of carcinoid tumor in the digestive organs. The 13 cases of carcinoid were identified from 18,267 pathological specimens of digestive organs in the last 10 years in our pathology laboratory. The tumor locations were rectum in 9 cases, duodenum in 2 cases, liver in 1 case, and stomach in 1 case. The age of the patients ranged from 52 to 82 years with a mean of 63 years. Male to female ratio was 7 : 6. The presenting symptoms were abnormal pain in 3 cases and asymptomatic in 10 cases. None of the cases showed carcinoid syndrome. The diameter ranged from 5 mm to 25 mm in gastrointestinal carcinoids, and 60 mm in the hepatic carcinoid. The treatment was endoscopic mucosal resection in 10 cases and surgical resection in 3 cases. The outcome is good except for hepatic atypical carcinoid which showed metastases and died of systemic metastasis. Histologically, 12 carcinoid tumors were typical carcinoids, and one (liver) was atypical carcinoid. Organoid pattern was present in 12 cases. Trabecular arrangement, ribbon arrangement, rosette formation, and pseudoglandular arrangement were recognized in 12 cases, in 8 cases, in 7 cases, and in 5 cases, respectively. Immunohistochemically, tumor cells were positive for at least one of pan-neuroendocrine markers including chromogranin, synaptophysin, neuron-specific enolase, CD56, and glucagon. Of these, synaptophysin was positive in 11/13 (85%), neuron-specific enolase 10/13 (80%), chromogranin 8/13 (62%), CD56 6/13 (46%), and glucagon 4/13 (31%). In summary, the author reported the incidence of digestive organ carcinoid tumors, and the clinicopathologic features of the 13 cases with carcinoid.


Materials and Methods
The author retrospectively reviewed 18,267 pathological specimens of digestive organs pathologic specimens in the last 10 years in our pathology laboratory in search for carcinoid tumors. In carcinoid tumors, clinical and pathologic records were reviewed, and the pathologic slides were re-examined.

Results
A total of 13 carcinoid tumors (0.07%) were found among the 18,267 digestive organ's pathologic specimens in the last 10 years in our pathology laboratory.
The carcinoid tumor locations were rectum in 9 cases, duodenum in 2 cases, liver in 1 case, and stomach in 1 case. The age of the patients ranged from 52 to 82 years with a mean of 63 years. Male to female ratio was 7 : 6. The presenting symptoms were abnormal pain in 3 cases and asymptomatic in 10 cases. None of the cases showed carcinoid syndrome. The diameter ranged from 5 mm to 25 mm in gastrointestinal carcinoids, and 60 mm in the hepatic carcinoid. The treatment was endoscopic mucosal resection in 10 cases and surgical resection in 3 cases. The outcome is good except for hepatic atypical carcinoid which showed metastases and died of systemic metastasis.

Discussion
In the present series, only 13 carcinoids were found in the 18,267 pathologic specimens in the last 10 years in our pathology laboratory. The incidence was 0.07%. The incidence of carcinoids of digestive organs is reported to be less than 0.1% of all digestive organ tumors [1][2][3]. Therefore, the incidence of 0.07 % in the present series is compatible with other institutes [1][2][3]. These findings suggest that carcinoids of digestive organs are rare.
In the present series, the locations of carcinoids were rectum in 9 cases, duodenum in 2 cases, liver in 1 case, and stomach in 1 case. A study of larger series indicated that the frequency of carcinoids of digestive organs is highest in the colon, followed in order by ileum, rectum, appendix, stomach, duodenum, jejunum, pancreas, and liver. Carcinoid of the liver is very rare [11]. The locations of carcinoids in this study were somewhat different from other institutes.
The presenting symptoms were abnormal pain in 3 cases and asymptomatic in 10 cases in the present series. None of the cases showed carcinoid syndrome. In general, patients with carcinoids present with non-specific symptoms such as abdominal pain and nausea [3]. The presenting symptoms depend on locations and size of carcinoids [3]. The tumor size of the present study was small. Therefore, asymptomatic patients predominate in the present study.
The prognosis of the present series is good except for the hepatic atypical carcinoid. In other institutes, five-year survival of carcinoids depends on tumor stage and tumor biologic behavior; it ranges from 60% to 98% [3].
In the present series, the treatment was endoscopic mucosal resection in 10 cases and surgical resection in 3 cases. It seems that the best choice of treatment is endoscopic resection in small carcinoids. In larger carcinoids, surgical operation may be effective.
Histopathologically, all cases but the hepatic atypical carcinoid showed typical features of carcinoids, such as trabecular, ribbon, rosette, and pseudoglandular arrangements, in the present series. The liver carcinoid of the present series may be a neuroendocrine carcinoma rather than atypical carcinoid.
Immunohistochemically, tumor cells were positive for cytokeratin in 7 cases and negative for carcinoembryonic antigen in all cases in the present series, suggesting that carcinoid tumor cells may be negative for cytokeratin. In the present series, the tumor cells were positive for at least one of pan-neuroendocrine markers including chromogran, synaptophysin, neuron-specific enolase, CD56, and glucagon. Of these, synaptophysin was positive in 11/13 (85%), neuron specific enolase 10/13 (80%), chromogranin 8/13 (62%),