Neuroendocrine differentiation is known to be one of the prognostic factors in many
carcinomas. However, the characteristics of neuroendocrine differentiation are not well elucidated in extrahepatic bile duct (EBD)
carcinomas. One hundred ninety-four cases of EBD
carcinomas were analyzed using immunohistochemistry with
synaptophysin and
chromogranin. The
tumors were graded as degree 0, 1, and 2 when the positive
tumor cells were 5% or less, 6% to 25%, and 26% or more, respectively. Immunohistochemical results were compared with clinicopathologic variables and survival rate.
Synaptophysin and
chromogranin were positive in 54 (27.8%) and 74 (38.1%) cases, respectively. Thirty-four cases (17.5%) were positive for both
synaptophysin and
chromogranin, 20 (10.3%) and 40 cases (20.6%) were positive only for
synaptophysin and for
chromogranin, respectively, and 100 cases (51.6%) were negative for both markers. There was a significant survival difference between overall
synaptophysin-positive (median, 27 months) and
synaptophysin-negative (38 months) groups (P < .05). However, there was no survival difference between
chromogranin-positive and
chromogranin-negative groups. There was a significant survival difference between the dual-positive expression to
synaptophysin and
chromogranin group (median, 21 months) and the dual-negative expression group (median, 35 months; P < .05). In summary,
synaptophysin expression was an important prognostic factor because
synaptophysin-positive cases showed a worse prognosis than
synaptophysin-negative cases. The more
tumor cells expressed
chromogranin, the poorer the survival. Therefore, immunohistochemical studies for neuroendocrine differentiation may be helpful in routine pathological examinations for evaluating the survival and the prognosis of patients with EBD
carcinomas.