Clinicopathological significance of mucin production in patients with papillary cholangiocarcinoma.

BACKGROUND: The clinicopathologic significance of mucin production in patients with papillary cholangiocarcinoma (PCC) is still controversial. We aimed at clarifying the similarities and differences between PCC cases with and without mucin secretion with regard to biological behavior and clinical course.
METHODS: Among 644 patients with surgically resected cholangiocarcinoma (1998-2011), 184 (28 %) patients were considered to have PCC and were enrolled in the study. Those patients were divided into two groups based on whether their PCC was mucin-producing (PCC-M, n = 89) or not (PCC-NM, n = 95). The presence of mucin secretion was determined by the cut surface of the specimens and by pathologic examination.
RESULTS: The clinicopathological features of PCC-M and PCC-NM largely overlapped. No significant between-group differences in malignant potential characteristics, including the depth of invasion, pathological T classification, and regional/periaortic lymph node metastasis, were observed (P = 0.193, 0.181, 0.083, and 0.674, respectively). However, a few clinicopathological differences existed between the two PCC types, i.e., the predominant histological type and epithelial subtype (P < 0.001 and P = 0.016, respectively). Immunohistochemically, MUC2, MUC5AC, MUC6, and HGM were more frequently expressed in PCC-M than PCC-NM (P < 0.002 in all). The disease-specific survival values were not significantly different between the two PCC types (PCC-M; 60 % at 5 year, PCC-NM; 46 %, P = 0.097).
CONCLUSION: PCC-M and PCC-NM were similar in morphology and prognosis. Although a few clinicopathological differences exist between them, their overlapping features and identical survival curves appear to justify the lack of a specific treatment modality for either type.