Cluster analysis of immunohistochemical profiles in synovial sarcoma, malignant peripheral nerve sheath tumor, and Ewing sarcoma

Abstract

As a result of overlapping morphologic and immunohistochemical features, it can be difficult to distinguish synovial sarcoma, malignant peripheral nerve sheath tumor, and Ewing sarcoma/primitive neuroectodermal tumor in core biopsies. To analyze and compare immunohistochemical profiles, we stained tissue microarrays of 23 synovial sarcomas, 23 malignant peripheral nerve sheath tumors, and 27 Ewing sarcomas with 22 antibodies potentially useful in the differential diagnosis, and analyzed the data with cluster analysis. Stain intensity was scored as none, weak, or strong. For CD99, tumors with membranous accentuation were independently categorized. Cluster analysis sorted five groups, with like tumors clustering together. Synovial sarcoma clustered into two groups: one cytokeratin and EMA positive (n ¼ 11), the other mostly cytokeratin negative, EMA positive, bcl-2 positive and mostly CD56 positive (n ¼ 9). Malignant peripheral nerve sheath tumor clustered into two groups: one S100 positive, with nestin and NGFR positivity in most (n ¼ 10), the other mostly S100 negative, and variably but mostly weakly positive for nestin and NGFR (n ¼ 11). Ewing sarcomas clustered into a single group driven by membranous CD99 staining. Thirteen cases failed to cluster (outliers), while three Ewing sarcomas clustered into groups of other tumor types. Paired antibodies for each tumor type determined by visual assessment of cluster analysis data and statistical calculations of specificity, sensitivity, and predictive values showed that EMA/CK7 for synovial sarcoma, nestin/S100 for malignant peripheral nerve sheath tumor, and membranous CD99/Fli-1 for Ewing sarcoma yielded high specificity and positive predictive values. Cluster analysis also highlighted aberrant staining reactions and diagnostic pitfalls in these tumors. Hierarchical cluster analysis is an effective method for analyzing high-volume immunohistochemical data.

Hierarchical cluster analysis of myoepithelial/basal cell markers in adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma

“…It is frequently used to analyze mRNA expression profiles of thousands of genes in DNA microarray studies. In recent years, this statistical tool has been applied to analyze immunohistochemical results on Formalinfixed paraffin-embedded tissues using multiple antibodies, and has demonstrated that tumors clustered into groups that correlated to their site of origin, 23 phenotype, 24,25 biologic potential, 26 and prognosis. [27][28][29] Our goal was to identify a cluster of markers that can be used in combination in a diagnostic immunohistochemical panel for differentiating adenoid cystic carcinoma from polymorphous low-grade adenocarcinoma.…”

Synovial sarcoma: Diagnosis on fine‐needle aspiration by morphology and molecular analysis

“…Thus, Olsen et al 18 performed a cluster analysis of the immunohistochemical profiles in RT-PCR proven cases of SS and concluded that EMA (sensitivity 91%) was the single most sensitive and specific marker that was positive in both bi and monophasic variants. Hence, for the retrospective analysis, we selected 16 cases (of the initial 20), which, on ICC, were positive for vimentin and epithelial membrane antigen or cytokeratin.…”

“…In a recent analysis, the most useful marker of SS was epithelial membrane antigen rather than cytokeratin. 18 Among the cytokeratins, CK7 is more specific for SS. 18 In addition S-100, NSE, synaptophysin, and CD34 may be applied to distinguish the sarcomas listed above.…”

Immunostaining for SYT protein discriminates synovial sarcoma from other soft tissue tumors: analysis of 146 cases

“…However, each of these markers can be expressed in a variety of other tumors. A recent study 20 used cluster analysis to analyze immunohistochemical data obtained from a tissue microarray of 73 soft tissue tumors (23 synovial sarcoma, 23 malignant peripheral nerve sheath tumor and 27 Ewing/PNET) with 22 different antibodies, including cytokeratin, CD99, EMA and bcl-2. The data suggested two clusters among synovial sarcoma, one cluster (n ¼ 11) was cytokeratin and EMA positive and another (n ¼ 9) was cytokeratin negative, but EMA, bcl-2 and mostly CD56 positive.…”

“…The study also highlighted aberrant staining reactions and diagnostic pitfalls in these tumors. 20 We believe the use of practical immunostaining assay for the SYT detection is likely to decrease the number of cases requiring large battery of studies for precise diagnosis of synovial sarcoma. If the staining shows an equivocal results or the case is histologically suspicious for a lesion other than synovial sarcoma such as a malignant peripheral nerve sheath tumor, various ancillary studies including molecular assays and electron microscopy could be performed as usual for further work-up.…”