Fibrosarcoma pathology

Fibrosarcoma was diagnosed much more frequently before the advent of immunohistochemical studies. It is currently believed to represent less than 1% of all adults. sarcomas. These tumors can arise de novo or within another sarcoma.

Histology fibrosarcoma

In fibrosarcoma, sections show a dermal (figure 1) or subcutaneous spindle cell tumor. The tumor may arise de novo or in association with another sarcoma. Figure 2 shows a fibrosarcoma (left) arising within a dermatofibrosarcoma protuberans (right) with arrows delineating the margin.

The tumor is composed of relatively uniform spindle cells that are deeply basophilic (Figures 2-4). Characteristically, the evil one The cells are arranged in a “herringbone” pattern (best seen in Figure 3). Mitosis They are generally easy to find (figure 4).

There are two different variants: the infantile variant and the sclerosing variant. epithelioid variant. Fortunately, these variants are extraordinarily rare in the skin.

Special studies for fibrosarcoma

An extensive immunohistochemical panel is essential to rule out other malignancies. The tumor is negative with S100 (essentially exclusive melanoma), keratins (except carcinoma and synovial sarcoma), smooth muscle markers (excluding leiomyosarcoma), CD34 (excluding dermatofibrosarcoma protuberans).

Differential diagnosis fibrosarcoma

Immunohistochemical studies are essential to exclude other sarcomas (see above).