Evaluation of a new paraffin-reactive CD7 T-cell deletion marker and a polymerase chain reaction-based T-cell receptor gene rearrangement assay: implications for diagnosis of mycosis fungoides in community clinical practice.
BACKGROUND
T-cell deletion and T-cell receptor (TCR) gene rearrangement studies are helpful in the early diagnosis and subsequent management of mycosis fungoides (MF). However, this often requires fresh-frozen tissue that can be difficult to obtain and evaluate in community clinical practice. A new CD7 antibody, the most sensitive and specific T-cell deletion marker, and a new TCR-gamma gene rearrangement polymerase chain reaction (PCR) assay (TCR-gamma PCR) are now available on routine paraffin-embedded biopsy specimens.


OBJECTIVE
Our purpose was to assess the utility of CD7 deletion and TCR-gamma PCR in the diagnosis of MF using routine paraffin-embedded biopsy material.


METHODS
Cases of MF (n = 17) with matching frozen tissue immunohistochemistry and benign reactive dermatoses (lichen planus; n = 27) were assessed for CD7 (Clone: CD7-272) deletion and TCR-gamma PCR using paraffin-embedded biopsy specimens.


RESULTS
Excellent concordance comparing frozen and paraffin embedded CD7 immunostaining (88%) was observed. CD7 deletion and TCR-gamma PCR was sensitive (94%) and specific (96%) for a diagnosis of MF using paraffin-embedded biopsy specimens.


CONCLUSIONS
In the diagnosis of MF, detection of CD7 deletion and monoclonal TCR rearrangements can be successfully performed in a cost-effective, timely fashion using routine formalin-fixed paraffin-embedded biopsy specimens.
Ormsby
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A
Department of Anatomic Pathology and Dermatology, The Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA.
Bergfeld
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WF
Tubbs
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Hsi
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D019011:Antigens, CD7; D017931:DNA Primers; D005260:Female; D017353:Gene Deletion; D015334:Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor / Q000235:genetics*; D019675:Genes, T-Cell Receptor gamma / Q000235:genetics; D006801:Humans; D008010:Lichen Planus / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009182:Mycosis Fungoides / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction / Q000592:standards; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology
D000911:Antibodies, Monoclonal; D019011:Antigens, CD7; D017931:DNA Primers