Summary Sclerosing epitheloid fibrosarcoma is a rare, histologically well- defined member of adult fibrosarcoma group of soft tissue tu- mors. Its main histological features are nests and cords of roun- ded tumor cells surrounded by hyalinized collagenous stroma. Epitheloid appearance with marked sclerosis and infiltrating growth pattern, along with occasional immunohistochemical po- sitivity for epithelial markers may be highly suggestive of infil- trating carcinoma. Despite of bland cytological features clinical course is often protracted with a high local recurrence rate and late metastases. In this report, we present histopathological cha- racteristics of two cases of sclerosing epitheloid fibrosarcoma, together with their clinical presentation, follow-up information and differential diagnosis. Riassunto Il fibrosarcoma epitelioide sclerosante costituisce una entità rara ma istologicamente ben caratterizzata appartenente al gruppo dei fibrosarcomi dell’adulto. La presenza di nidi e cordoni di cellule tumorali tondeggianti circondate da uno stroma collagene ialin- izzato costituisce la principale caratteristica istologica del fibrosarcoma epitelioide sclerosante. L’aspetto epitelioide con evi- dente sclerosi, il pattern di crescita infiltrativo e l’occasionale immunoreattività per markers epiteliali possono simulare un car- cinoma infiltrante e costituire una insidia diagnostica. Nonostante l’aspetto citologico blando, il decorso clinico è spesso sfavorev- ole in ragione dell’elevata frequenza di recidive locali e di più tardive metastasi. In questo articolo vengono descritte le carat- teristiche istopatologiche di due casi di fibrosarcoma epitelioide sclerosante, discutendone le possibili diagnosi differenziali; sono inoltre riportati i dati di presentazione clinica e di follow-up. PATHOLOGICA 2004;96:433-435 Parole chiave Soft tissue tumors • Fibrosarcoma • Sclerosing epitheloid fibrosarcoma Key words Tumori dei tessuti molli • Fibrosarcoma • Fibrosarcoma epite- lioide sclerosante CASO CLINICO Sclerosing epitheloid fibrosarcoma. A report of two cases Fibrosarcoma epitelioide sclerosante. Descrizione di due casi J. BEZIΔ, S. TOMIΔ, M. GLAVINA-DURDOV, D. ALFIREVIΔ, I. πAMIJA, S. KRIÆANAC 1 Department of Pathology, Clinical Hospital Split, Split, Croatia; 1 Institute of Pathology, School of Medicine, University of Zagreb, Zagreb, Croatia Corrispondenza Dr. Josko BeziΔ, Clinical Hospital Split, Department of Patho- logy, Spin»iΔeva 1, 21000 Split, Croatia - Tel. +385 021 556513 - Fax +385 021 389563 - E-mail: jb@mefst.hr Introduction For many years, fibrosarcoma was a frequent histo- pathological diagnosis because it was broadly defined as a sarcoma showing collagen production. At the pre- sent time fibrosarcoma is essentially diagnosis of ex- clusion reserved for those soft tissue tumors composed of spindle cells that immunohistochemically express no other marker than a vimentin. Though relatively rare in times of imunohistochemistry and ultrastructural analysis, well defined histological variants of fibrosar- coma are still present 1 2 . We have presented here two cases of sclerosing epitheloid fibrosarcoma (SEF) whi- ch is clinicopathologically distinct member of the adult fibrosarcoma group. Clinical cases CASE 1 A 62 years old man with a painful mass in the thenar re- gion of the right hand, first observed at the end of 1995. In January 1996 a wide surgical tumor excision was performed. During the surgical procedure a tumor infil- tration of two digital nerves was observed. On gross in- spection tumor represented a well-circumscribed, par- tially cystic gray-white mass of 4 cm in diameter. The first recurrence forming a solid, lobular, white-gray tu- mor of 3,5 cm in diameter, in the area of surgical scar was documented in September 1996, when reexcision was performed. The second recurrence in the same area was observed in January 1997, when wide surgical ex- cision of thenar region with thumb amputation was ma- de. This time tumor was poorly circumscribed white