Biomarker‐assisted diagnosis of ovarian, cervical and pulmonary small cell carcinomas: the role of TTF‐1, WT‐1 and HPV analysis

Abstract

Small cell carcinoma of the ovary, hypercalcaemic-type (SCCOH) is morphologically similar to small cell carcinomas from other sites. The aims of this study were to (i) determine if a biomarker panel would distinguish small cell carcinomas of the ovary, cervix (SCCCx) and lung (SCCLu) and (ii) potentially determine the histogenesis of SCCOH. Nine ovarian small cell carcinomas (seven hypercalcaemic type; two pulmonary type), eight SCCCx and 22 SCCLu were immunostained for thyroid transcription factor (TTF)-1, WT-1, p16, cKIT and OCT3/4; a subset of cases were tested for human papillomavirus (HPV). WT-1 was diffusely positive in 6/7 SSCOH versus two of 33 other small cell carcinomas (P <or= 0.001). TTF-1 was diffusely positive in 20/22 SCCLu and 1/8 SCCCx, and negative in all SCCOH. p16 and cKIT demonstrated variable patterns of immunoreactivity in all cases. HPV was identified in 5/6 SCCCx; SCCOH and SCCLu were negative for HPV. Combined staining with WT-1 and TTF-1 will distinguish SCCOH from SCCLu and SCCCx with a sensitivity of 86% and specificity of 97%. HPV is specific for tumours of cervical origin, but p16 immunohistochemistry is not useful for this purpose. The presence of diffuse WT-1 supports a Müllerian origin for SCCOH, whereas the absence of cKIT and OCT3/4 argues against a germ cell origin.