Myogenin expression in vulvovaginal spindle cell lesions: analysis of a series of cases with an emphasis on diagnostic pitfalls.
OBJECTIVE
Myogenin (myf4) is a nuclear transcription factor that is considered to be a sensitive and highly specific marker for skeletal muscle differentiation. Following the identification of focal strong nuclear staining with myogenin in two fibroepithelial polyps of the lower female genital tract (the index cases), we stained a series of vulvovaginal spindle cell lesions with this marker in order to investigate how widespread myogenin staining is in these lesions.


RESULTS
Fibroepithelial polyps (n = 13), other vulvovaginal mesenchymal lesions (n = 21) and vulval or vaginal spindle cell squamous carcinomas (n = 4) were stained for myogenin. Apart from the index cases, all of the other cases were negative, except for one vaginal spindle cell squamous carcinoma, which showed focal weak nuclear immunoreactivity. Ten of 12 embryonal rhabdomyosarcomas of the lower female genital tract were myogenin-positive, as was a single vaginal rhabdomyoma.


CONCLUSIONS
Our study illustrates that focal myogenin immunoreactivity occurs uncommonly in fibroepithelial polyps of the lower female genital tract. This may result in diagnostic confusion and misdiagnosis as a skeletal muscle neoplasm, especially the sarcoma botryoides variant of embryonal rhabdomyosarcoma.
Department of Pathology, Belfast Health and Social Care Trust, Belfast, UK.
W Glenn
WG
McCluggage
Teri A
TA
Longacre
Cyril
C
Fisher
D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D018008:Myogenin / Q000032:analysis / Q000096:biosynthesis*; D011127:Polyps / Q000175:diagnosis* / Q000378:metabolism; D012208:Rhabdomyosarcoma / Q000175:diagnosis; D014625:Vaginal Neoplasms / Q000175:diagnosis* / Q000378:metabolism
D014408:Biomarkers, Tumor; D018008:Myogenin
cervix; immunohistochemistry; myogenin; vagina; vulva