Background-Neuroendocrine cell (NEC) carcinoma is occasionally accompanied
by adenocarcinoma but the relationship between these two morphologically di
stinct tumours is unclear. Two hypotheses have arisen regarding the mechani
sm for the association of adenocarcinoma and NEC carcinoma. One is that bot
h are derived from a common multipotential epithelial stem cell. The second
hypothesis is that adenocarcinoma and NEC carcinoma arise from a multipote
ntial epithelial stem cell and a primitive NEC, respectively.
Aims-To elucidate the relationship between the two histologically distinct
tumours, adenocarcinoma of the stomach and NEC carcinoma of the duodenum.
Patient/methods-We present a case in which the tumour extended across the p
yloric ring, the gastric portion of which revealed adenocarcinoma while the
duodenal portion showed argyrophil NEC carcinoma. The two histologically d
istinct lesions of the tumour were examined by immunohistochemistry and gen
etic analysis of p53.
Results-The gastric region was negative for chromogranin A staining but pos
itive for carcinoembryonic antigen (CEA) staining. In contrast, the duodena
l region was positive for chromogranin A but negative for CEA. All tumour r
egions showed a point mutation in p53 gene at exon 7 (GGC (glycine)--> GTC
(valine) at codon 245). The distal portion of the duodenal tumour showed an
additional point mutation in p53 gene at exon 5 (GCC (alanine)--> GTC (val
ine) at codon 129).
Conclusions-The two histologically distinct tumours, adenocarcinoma of the
stomach and NEC carcinoma of the duodenum, appear to be derived from a comm
on epithelial cell.