Calponin and MUC6 complement inhibin as diagnostic immunomarkers of serous cystadenoma in endoscopic ultrasound‐guided aspiration/biopsy specimens

Abstract

Calponin and MUC6 complement inhibin as diagnostic immunomarkers of serous cystadenoma in endoscopic ultrasound-guided aspiration/biopsy specimens Aims: Because serous cystadenoma (SCA) does not usually require excision, it is critical to distinguish it from differential diagnoses which do, especially neuroendocrine tumour (NET). The gold standard for diagnosing SCA is assessment of endoscopic ultrasound-guided fine needle aspiration/biopsy (EUS-FNAB) material. Inhibin immunohistochemistry aids this assessment, but such positivity is not absolutely sensitive or specific to SCA. The following is the largest known study of SCA EUS-FNAB specimens and the first to compare four potential SCA immunomarkers between themselves and inhibin, compared against NET. Methods and results: Immunohistochemistry for calponin, mucin 6 (MUC6), glucose transporter 1 (GLUT1) and vascular endothelial growth factor A (VEGFA) was performed on 30 EUS-FNAB and three resection specimens of SCA and 32 EUS-FNAB specimens of NET. GLUT1 and VEGFA were suboptimal as diagnostic immunomarkers of SCA, being expressed by 10 and 44% of NETs, respectively. Further, their expression by cellular constituents of blood which often contaminate EUS-FNAB specimens hampered identification of neoplastic cells, especially in hypocellular samples. While 19% of NETs showed nuclear MUC6 positivity, cytoplasmic expression of the protein showed 100% specificity and sensitivity as an SCA marker. However, assessing MUC6 in EUS-FNAB specimens must also consider the protein's focal expression in physiological pancreatic, gastric or duodenal tissues, which can contaminate these specimens. Calponin was less sensitive (71% versus 100%) but more specific (100% versus 91%) than inhibin, although easier to assess in EUS-FNAB specimens than MUC6. Conclusions: Of the four potential immunomarkers of SCA suggested by the existing literature, calponin and MUC6 are useful complementary studies to inhibin for application to EUS-FNAB specimens.

Novel insights into immunohistochemical analysis for diagnosing serous neoplasm of the pancreas: aquaporin 1, stereocilin, and transmembrane protein 255B

“…10 Calponin and MUC6 were reported to be effective in distinguishing serous cystadenoma from NET. 24 Although our results were obtained from surgical specimens and a small biopsy cohort, we believe that their high expression rates will contribute to better preoperative diagnoses.…”

Pax8 as a useful adjunct marker to differentiate pancreatic serous cystadenoma from clear cell renal cell carcinoma in both cytologic and surgical specimens

“…Pax8 immunoreactivity was interpreted using nuclear staining alone, whereas inhibin immunoreactivity was interpreted using cytoplasmic staining [ 2 , 10 , 11 , 19 ]. The percentage of Pax8- or inhibin-immunoreactive tumor cells was scored as a proportion.…”

“…Pancreatic serous cystadenoma (SCA) is a benign, yet important, epithelial neoplasm that is largely composed of small uniform cuboidal glycogen-rich cells that often form cysts containing serous fluid [ 1 , 2 ]. Imaging studies, such as computed tomography (CT) or endoscopic ultrasonography (EUS), largely facilitate the diagnosis of SCA [ 2 , 3 ]. However, cytohistological evaluations remain the gold standard for a definitive diagnosis [ 2 , 4 – 6 ].…”

“…Imaging studies, such as computed tomography (CT) or endoscopic ultrasonography (EUS), largely facilitate the diagnosis of SCA [ 2 , 3 ]. However, cytohistological evaluations remain the gold standard for a definitive diagnosis [ 2 , 4 – 6 ].…”

Atypical cells in fine needle aspiration biopsies of pancreas: Causes, work‐up, and recommendations for management

“…Tumor cells are bland and cuboidal and contain glycogen rich clear cytoplasm. They stain positively for pancytokeratin, PAS, calponin, MUC6, and inhibin 65 as well as GLUT1. 66 CD31 may also be used to highlight their subepithelial capillary meshwork.…”