[60] Pleomorphic Fibrosarcoma of Skin and Soft Tissues. Clinicopathologic, Immunohistochemical, and Ultrastructural Analysis of 145 Cases

Thomas Mentzel, Claudia Otto, Detlef Katenkamp. Dermatopathology Bodensee, Friedrichshafen, Germany; University of Freiburg, Freiburg, Germany; University of Jena, Germany

Background: Fibrosarcoma of skin and soft tissues as defined in the current WHO-classification represents a very rare entiy and its morphologic features may be seen in different neoplasms. We report a series of pleomorphic fibrosarcomas and discuss its relationship to other pleomorphic sarcomas.
Design: The consultation files of the authors and databases of our institutions were searched for cases coded as fibrosarcoma of pleomorphic sarcoma. All other lines of differentiation have been excluded by histological, immunohistochemical and molecular studies, and the remaining cases showing features of classical fibrosarcoma and pleomorphic sarcoma with fibroblastic/myofibroblastic differentiation were included.
Results: The 145 cases occurred in 79 men and 65 women (gender was unknown in 1 case) with a age range from 20 to 99 years (median: 69 years). The neoplasms arose on the lower (41) and upper (17) extremities, the head/neck region (29), the trunk (21), the pelvic region (7), the retroperitoneum (6), intrathoracal (3), the genital area (3), the buttock (3), the hands and feet (4), intraoral (2), the kidney (1), and in unknown location (8). 23 neoplasms arose in dermosubcutaneous location, 9 cases in the subcutis, and the other neoplasms in deep soft tissues. 18 cases showed morphologic features of classical fibrosarcoma of adults, composed of cellular fascicles of atypical spindled fibroblastic cells, in 45 cases a transition to areas of high-grade pleomorphic sarcoma was seen, and 82 cases showed features of high-grade spindle cell/pleomorphic sarcoma with fibroblastic/myofibroblastic differentiation. The mitotic rate was increased, and tumor necrosis was noted in 43 cases. Immunohistochemically, 49% of cases tested showed a focal expression of actin, 15% a focal expression of CD 34, and 78% a focal expression of CD68. The remaining antibodies were negative. FISH-analysis in selected cases did not reveal characteristic changes for neoplasms that have to be considered in the differential diagnosis. Ultrastructural analysis in 10 cases revealed features of neoplastic fibroblasts with abundant rough endoplasmic reticulum and extracellular collagen.
Conclusions: Pleomorphic fibrosarcoma represents a distinct subgroup in the spectrum of pleomorphic sarcomas of skin and soft tissues. Further clinicopathological and follow-up studies are necessary to evaluate differences to other pleomorphic sarcomas of skin and soft tissues.
Category: Bone & Soft Tissue

Monday, March 4, 2013 1:00 PM

Poster Session II # 25, Monday Afternoon


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