title: Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma.
abstract: OBJECTIVE
  The aims of this study were to clarify the usefulness of immunohistochemistry in the differential diagnosis of epithelioid mesothelioma with a solid growth pattern [solid epithelioid mesothelioma (SEM)] and poorly differentiated squamous cell carcinoma (PDSCC), and to confirm the validity of a specific type of antibody panel. Additionally, we aimed to clarify the pitfalls of immunohistochemical analyses.
  
  
  RESULTS
  Formalin-fixed paraffin-embedded specimens from 36 cases of SEM and 38 cases of PDSCC were immunohistochemically examined for calretinin, podoplanin (D2-40), Wilms' tumour gene product (WT1), cytokeratin (CK) 5/6, p40, p63, carcinoembryonic antigen (CEA), epithelial-related antigen (MOC31), claudin-4, thyroid transcription factor-1 (TTF-1), and napsin A. WT1 showed the highest diagnostic accuracy (85.1%) as a mesothelial marker, and CEA, p40 and claudin-4 showed higher diagnostic accuracies (95.9%, 94.6%, and 93.2%, respectively) as carcinoma markers. Calretinin (diagnostic accuracy: 75.7%), D2-40 (diagnostic accuracy: 67.6%), CK5/6 (diagnostic accuracy: 63.5%), TTF-1 (diagnostic accuracy: 55.4%) and napsin A (diagnostic accuracy: 52.7%) could not differentiate between SEM and PDSCC. Among these markers, the combination of calretinin and WT1 showed the highest diagnostic accuracy (86.5%) as a positive marker, and the combination of p40 and CEA showed the highest diagnostic accuracy (97.3%) as a negative marker. The combination of CEA and claudin-4 also showed relatively high diagnostic accuracy (94.6%) as a negative marker.
  
  
  CONCLUSIONS
  We recommend the combination of WT1 and calretinin as a positive maker, and the combination of CEA and claudin-4 as a negative marker, for differential diagnoses of SEM and PDSCC.
authors: Department of Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors: Kei
authors: K
authors: Kushitani
authors: Department of Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors: Vishwa J
authors: http://orcid.org/0000-0002-4986-2109
authors: VJ
authors: Amatya
authors: Faculty of Medicine, Hiroshima University, Hiroshima, Japan.
authors: Yasuko
authors: Y
authors: Okada
authors: Faculty of Medicine, Hiroshima University, Hiroshima, Japan.
authors: Yuya
authors: Y
authors: Katayama
authors: Department of Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Department of Pathology and Clinical Pathology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt.
authors: Amany S
authors: AS
authors: Mawas
authors: Department of Surgical Oncology, Research Centre for Radiation Casualty Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
authors: Yoshihiro
authors: Y
authors: Miyata
authors: Department of Surgical Oncology, Research Centre for Radiation Casualty Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
authors: Morihito
authors: M
authors: Okada
authors: Department of Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Pathologic Diagnostic Centre, Inc., Hiroshima, Japan.
authors: Kouki
authors: K
authors: Inai
authors: Department of Internal Medicine, Okayama Rosai Hospital, Okayama, Japan.
authors: Takumi
authors: T
authors: Kishimoto
authors: Department of Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors: Yukio
authors: Y
authors: Takeshima
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis*; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000175:diagnosis*; D008654:Mesothelioma / Q000175:diagnosis*; D000086002:Mesothelioma, Malignant; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor
keywords: WT1 protein; calretinin; carcinoembryonic antigen; claudin-4; immunohistochemistry; mesothelioma; p40; squamous cell carcinoma