WT1 staining reliably differentiates desmoplastic small round cell tumor from Ewing sarcoma/primitive neuroectodermal tumor : An immunohistochemical and molecular diagnostic study

• Published in: American journal of clinical pathology 2000-09, Vol.114 (3), p.345-353
• Main Authors: HILL, D. Ashley, PFEIFER, John D, MARLEY, Edith F, DEHNER, Louis P, HUMPHREY, Peter A, XIAOPEI ZHU, SWANSON, Paul E
• Format: Article
• Language: English
• Subjects: Abdominal Neoplasms - diagnosis; Abdominal Neoplasms - genetics; Abdominal Neoplasms - metabolism; Adolescent; Adult; Biological and medical sciences; Biomarkers, Tumor - metabolism; Blotting, Southern; Child; Child, Preschool; Diagnosis, Differential; DNA Primers - chemistry; DNA, Neoplasm - analysis; DNA-Binding Proteins - metabolism; Female; Fibromatosis, Aggressive - diagnosis; Fibromatosis, Aggressive - genetics; Fibromatosis, Aggressive - metabolism; Humans; Immunoenzyme Techniques; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Miscellaneous. Technology; Neuroectodermal Tumors, Primitive - diagnosis; Neuroectodermal Tumors, Primitive - genetics; Neuroectodermal Tumors, Primitive - metabolism; Oncogene Proteins, Fusion - metabolism; Parotid Neoplasms - diagnosis; Parotid Neoplasms - genetics; Parotid Neoplasms - metabolism; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Reverse Transcriptase Polymerase Chain Reaction; Sarcoma, Ewing - diagnosis; Sarcoma, Ewing - genetics; Sarcoma, Ewing - metabolism; Sequence Analysis, DNA; Transcription Factors - metabolism; WT1 Proteins
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/114.3.345

Differentiating desmoplastic small round cell tumor (DSRCT) from another similar small round cell tumor of childhood, the Ewing sarcoma/primitive neuroectodermal tumor (EWS/PNET), can be difficult because morphologic and immunohistochemical features overlap. We studied the predictive value of immunohistochemistry with an antibody to the C-terminal region of the Wilms tumor (WT1) protein for differentiating DSRCT from EWS/PNET in 24 malignant small round cell tumors that had been previously diagnosed as DSRCT or EWS/PNET by standard methods. We performed reverse transcriptase-polymerase chain reaction (RT-PCR) analysis in cases with available tissue as a confirmatory measure: 6 of 13 DSRCTs were informative by RT-PCR, and 6 of 6 showed an EWS-WT1 fusion; all 13 DSRCTs showed strong, definitive nuclear staining with the WT1 antibody. All 11 EWS/PNETs were WT1 antibody negative; 7 of 11 cases classified as EWS/PNET were informative by RT-PCR, and 7 of 7 showed an EWS-FLI-1 fusion. For cases in which the morphologic and immunohistochemical features are consistent with a diagnosis of DSRCT, WT1 antibody staining predicts the EWS-WT1 translocation with high sensitivity and specificity and is, therefore, useful for differentiating DSRCT from EWS/PNET when genetic information is unavailable.