Small cell carcinomas in gastrointestinal tract: immunohistochemical and clinicopathological features.
OBJECTIVE
To test the incidence of the expression of the immunohistochemical markers that aid diagnosis of gastrointestinal tract small cell carcinoma (GI-SmCC) and to evaluate the incidence of mixed endocrine-exocrine carcinomas in GI-SmCC.


METHODS
Immunohistochemical studies of three antibodies against epithelial markers (CK8, AE1/AE3, EMA), four neuroendocrine differentiation markers (synaptophysin (Syn), neuron specific enolase (NSE), neuronal cell adhesion molecules (CD56), chromogranin A (CgA)), and a transcription factor (thyroid transcription factor 1 (TTF-1)) were performed. The incidence of non-endocrine carcinoma component was evaluated in 42 GI-SmCCs (11 in the oesophagus, 15 in the stomach, 15 in the colon, and 1 in the small intestine).


RESULTS
The percentages of GI-SmCC with positive immunoreactivity were: CK8 92.9%, AE1/AE3 76.2%, EMA 71.4%, Syn 100%, NSE 100%, CD56 90.5%, CgA 61.9%, TTF-1 21.4%. The low molecular weight cytokeratin CK8 is more commonly expressed in GI-SmCC than is the expression of AE1/AE3 or EMA. Synaptophysin and NSE are expressed in all GI-SmCCs studied. Non-endocrine carcinoma components were demonstrated in 8 patients (4 in the oesophagus and 4 in the stomach).


CONCLUSIONS
In detecting GI-SmCC, epithelial marker CK8 is more sensitive than AE1/AE3 or EMA, and neuroendocrine differentiation markers synaptophysin and NSE are the most useful markers. TTF-1 positivity is not uncommon in GI-SmCC, but cases with negative TTF-1 staining may indicate an extra-pulmonary primary. Non-endocrine carcinoma components were demonstrated in about 30% of oesophagus and stomach SmCC; the neoplasms should be diagnosed as mixed endocrine-exocrine carcinoma.
Li
Anna Fen-Yau
AF
School of Medicine, National Yang-Ming University, Taipei, Taiwan. fyli@vghtpe.gov.tw
Li
Alice Chia-Heng
AC
Hsu
Chih-Yi
CY
Li
Win-Yin
WY
Hsu
Han-Shui
HS
Chen
Jeou-Yuan
JY
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D018288:Carcinoma, Small Cell / Q000378:metabolism* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D004938:Esophageal Neoplasms / Q000378:metabolism / Q000473:pathology; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018198:Mixed Tumor, Malignant / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism; D012189:Retrospective Studies
D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins