Sclerosing epithelioid fibrosarcoma: a study of five cases emphasizing diagnostic criteria

Aims To study the clinical and histopathological features of sclerosing epithelioid fibrosarcoma, and to define diagnostic criteria for this uncommon soft‐tissue tumour. Methods and results Standard histological, immunohistochemical and ultrastructural techniques were applied to five tumours from head and neck, chest wall and groin. Tumours consisted of groups of monomorphic rounded/epithelioid cells surrounded by a prominent collagenous stroma. Tumour cells showed positive vimentin staining but were negative for other markers. They contained prominent rough endoplasmic reticulum and a large Golgi apparatus which in one case was producing collagen secretion granules, an ultrastructural marker for collagen production. Three patients had medium to long‐term survival (3–7 years). Of these, one was disease‐free for 3 years, and two experienced multiple recurrences: one of the latter died of metastatic disease. Conclusion Criteria for diagnosing this uncommon tumour include: small to medium cell size, clear or pale cytoplasm, cellular arrangement in cords and strands, dense collagenous stroma; vimentin staining; rough endoplasmic reticulum and a Golgi apparatus producing, in well preserved examples, collagen secretion granules. The paper emphasizes the value of electron microscopy, supporting an appropriate histological picture and immunophenotype, in identifying these relatively low‐grade sarcomas.