Expression and diagnostic values of calretinin and CK5/6 in cholangiocarcinoma

Our plain-English summary of Expression and diagnostic values of calretinin and CK5/6 in cholangiocarcinoma, by L. Zhang, R. Frank, E.E. Furth, et al (Experimental Hematology & Oncology, 2014).

The study

• Authors: L. Zhang, R. Frank, E.E. Furth, A.F. Ziober, V.A. LiVolsi, P.J. Zhang
• Journal: Experimental Hematology & Oncology
• Published: 2014;3:12
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Mesothelin, a mesothelial marker, has been found expressed in and as a potential treatment target of cholangioacarcinoma (CC). It is possible that CC may be derived from the cells sharing mesothelial markers. However, the expression of other mesothelial markers in CC is largely unknown.

Methods: Thirty CC cases (10 extrahepatic and 20 intrahepatic) were retrieved from our institutional archive. The immunohistochemical study of Calretinin (DC8), WT1 (6F-H2), Lymphatic Endothelial Marker (D2-40), CK5/6 (D5/16 B4) and CK19 (b170) was done on formalin fixed paraffin embedded sections for 2-3 blocks of each case. We compared the expression levels between CC and normal bile duct (NBD) on the same block.

Results: All of the CC and NBD are positive for CK19 (23/23) and negative for WT1 (0/23) and D2-40 (0/23), except one CC positive for D2-40(1/30, 3.3%) and one NBD positive for WT1 (1/23, 4.3%). Calretinin immunoreactivity was detected in 52.2% (12/23) of CC, but none in NBD (0/23). CK5/6 was also detectable in 73.3% (22/30) of CC and all NBD (30/30). Increased expression of calretinin and reduced expression of CK5/6 were more likely associated with CC than NBD (P < 0.001 and P = 0.002, respectively). The sequential staining pattern of positive calretinin and negative CK5/6 in calretinin negative cases has a sensitivity of 69.57% and a specificity of 100% for differentiating CC from NBD. CK5/6 expression was also more likely associated with well-differentiated CC (7/7 versus 12/20 in moderately differentiated, and 9/10 in poorly differentiated, P = 0.019) and extrahepatic CC (10/10 versus 12/20 in intrahepatic, P = 0.029), but there was no association between the calretinin expression and the CC grade or location.

Conclusion: Calretinin and CK5/6 immunohistochemical stains may be useful for diagnosing a CC. Their immunohistochemical results should be interpreted with caution in the cases with differential diagnoses of mesothelioma and CC. A full mesothelioma panel, including WT1 and/or D2-40, is recommended to better define a mesothelial lineage. The biology of calretinin and CK5/6 expression in CC is unclear, but might shed light on identifying therapeutic targets for CC.

In plain English

This study did not examine asbestos exposure. It was a retrospective laboratory study of 30 bile duct cancers (cholangiocarcinomas: 10 extrahepatic, 20 intrahepatic) from the authors' institutional archive. The authors stained tumor and nearby normal bile duct for markers used to identify mesothelioma (calretinin, WT1, D2-40, CK5/6) and for CK19. Calretinin was positive in 12 of 23 bile duct cancers (52.2%, 95% CI 30.6 to 73.2%) and in none of the 23 normal bile ducts. CK5/6 was negative in 8 of 30 cancers (26.7%, 95% CI 12.3 to 45.9%) and in none of the 30 normal ducts. WT1 and D2-40 were nearly always negative: one normal duct was WT1-positive and one cancer was D2-40-positive. In this series, a two-step staining rule correctly identified 16 of 23 cancers (sensitivity 69.57%) and 23 of 23 normal ducts (specificity 100%). The authors concluded that these stains may help diagnose bile duct cancer. They advised caution when mesothelioma is also a possible diagnosis and recommended a full mesothelioma panel including WT1 and/or D2-40. They did not compare these cancers directly with mesothelioma.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective immunohistochemistry (tissue staining) study comparing tumor tissue with adjacent normal bile duct on the same slide
• Who was studied: 30 resected cholangiocarcinoma cases (10 extrahepatic, 20 intrahepatic) from the authors' institutional archive (University of Pennsylvania pathology department), each with nearby normal bile duct on the same block. Calretinin, CK19 and WT1 stains were done on only 23 of the 30 cases because additional blank slides were difficult to obtain.
• Exposure: No asbestos or other environmental or occupational exposure was studied. The study examined staining for calretinin, WT1, D2-40, CK5/6 and CK19 in bile duct cancer and normal bile duct.
• Main results:
  • Calretinin was positive in 12 of 23 cholangiocarcinomas (52.2%, 95% CI 30.6 to 73.2%) and in 0 of 23 normal bile ducts (P less than 0.001).
  • CK5/6 was negative in 8 of 30 cholangiocarcinomas (26.7%, 95% CI 12.3 to 45.9%) and in none of the 30 normal bile ducts (P = 0.002).
  • Compared with the adjacent normal bile duct, the cancer stained weaker for CK5/6 in 18 cases (60.0%), similarly in 10 (33.3%) and stronger in 2 (6.67%).
  • WT1 and D2-40 were negative in all cancers and all normal ducts except 1 normal duct positive for WT1 (1/23, 4.3%) and 1 cancer positive for D2-40 (1/30, 3.3%). There was no significant difference between cancer and normal duct for CK19, WT1 or D2-40.
  • Under a sequential rule, a case counted as cancer if it was calretinin-positive, or if it was calretinin-negative and CK5/6-negative. In this series the rule identified 16 of 23 cholangiocarcinomas (sensitivity 69.57%) and classified 23 of 23 normal bile ducts correctly (specificity 100%).
  • CK5/6 expression was more likely in well-differentiated cholangiocarcinoma (7/7 positive, compared with 9/10 poorly differentiated; P = 0.019) and in extrahepatic cholangiocarcinoma (10/10, compared with 12/20 intrahepatic; P = 0.029). The figure printed for moderately differentiated tumors differs between the abstract and Table 5 (see text problems).
  • Calretinin expression was not associated with tumor grade or location.
• The authors' conclusion: The authors concluded that calretinin and CK5/6 stains may be useful for diagnosing cholangiocarcinoma. They said the results should be interpreted with caution when both mesothelioma and cholangiocarcinoma are possible diagnoses, and they recommended a full mesothelioma panel including WT1 and/or D2-40.
• Limitations the authors state:
  • As a retrospective study, it may have selection bias.
  • Calretinin and CK5/6 staining was not compared between cholangiocarcinoma, mesothelioma and hepatocellular carcinoma.
  • Staining in reactive bile duct changes and benign bile duct tumors was not assessed.
  • Prognostic value and survival were not studied.

Topics

Medical terms in this study, explained in our Lexicon: Calretinin, Mesothelin, Podoplanin (D2-40), Well-Differentiated, Mesothelioma.

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