Epithelioid sarcoma: New insights based on an extended immunohistochemical analysis

Archives of Pathology & Laboratory Medicine, Sep 2003 by Laskin, William B, Miettinen, Markku

Our extended immunohistochemical study of 95 examples of classic ES and its variants has revealed some interesting and potentially useful results. From a differential diagnosis perspective, ES involving the skin and dermis can potentially mimic a poorly differentiated cutaneous squamous cell carcinoma, whereas the large cell/rhabdoid variant by virtue of its deep location and larger cell size may cause confusion with carcinoma or possibly epithelial mesothelioma. We found that p63, a keratinocyte stem cell marker, together with K 5/6 distinguishes cutaneous squamous carcinoma from all subtypes of ES. Along with absence of CD34, strong coexpression of 2 of the 3 mesothelioma-related markers, calretinin, K 5/6, and mesothelin, and strong expression of either K 5/6, p63, or K 20 would favor mesothelioma and carcinoma, respectively, over the large cell/rhabdoid variant of ES. In addition, our study found no single immunomarker able to separate the different histologic subtypes of ES, thus confirming an observation made in a previous study8 that all histologic subtypes of ES are histogenetically related. Finally, with the exception of the simple keratins (K 8, 18, and 19), the keratin subtypes used in our study generally showed limited expression. We believe that this latter finding coupled with the data reported in a previous study of ES from the Institute8 support the notion that ES is a mesenchymal neoplasm that is capable of undergoing partial epithelial transformation.

References

1. Laskowsky J. Sarcoma aponeuroticum. Nowotwory. 1961;11:61-67.

2. Dabska M, Koszarowski T. Clinical and pathologic study of aponeurotic (epithelioid) sarcoma. Pathol Ann. 1982;17:129-153.

3. Enzinger FM. Epithelioid sarcoma: a sarcoma simulating a granuloma or a carcinoma. Cancer. 1970;26:1029-1041.

4. Chase DR, Enzinger FM. Epithelioid sarcoma: diagnosis, prognostic indicators, and treatment. Am J Surg Pathol. 1985;9:241-263.

5. Bos GD, Pritchard DJ, Reiman HM, et al. Epithelioid sarcoma: an analysis of fifty-one cases. J Bone Joint Surg Am. 1988;70:862-870.

6. Evans HE, Baer SC. Epithelioid sarcoma: a clinicopathologic and prognostic study of 25 cases. Semin Diagn Pathol. 1993;10:286-291.

7. Hailing AC, Wollen PC, Pritchard DJ, Vlasak R, Nascimento AG. Epithelioid sarcoma: a clinicopathologic review of 55 cases. Mayo Clin Proc. 1996;71:636-642.

8. Miettinen M, Fanhurg-Smith JC, Virolainen M, Shmookler BM, Fetsch JF. Epithelioid sarcoma: an immunohistochemical analysis of 112 classical and variant cases and a discussion of the differential diagnosis. Hum Pathol. 1999:30:934-942.

9. Santiago H, Feinerman LK, Lattes R. Epithelioid sarcoma, a clinical and pathologic study of nine cases. Hum Pathol 1972;3:133-147.

10. Guillou L, Wadden C, Coindre J-M, Krausz T, Fletcher CDM. "Proximaltype" epithelioid sarcoma, a distinctive aggressive neoplasm showing rhabdoid features: clinicopathological, immunohistochemical and ultrastructural study of a series. Am J Surg Pathol. 1997;21:130-146.

11. Mirra JM, Kessler S, Bhuta S, Eckardt J. The fibroma-like variant of epithelioid sarcoma: a fibrohistiocytic/myoid cell lesion often confused with benign and malignant spindle cell tumors. Cancer. 1992;69:1382-1395.