The Morphological Variations of Fibrous Histiocytomas.

The morphological variants of dermal fibrous histiocytomas have engendered a confusing terminology. One hundred and eighty-nine cases of fibrous histiocytomas were studied in order to define the morphological spectrum exhibited by these lesions. Based on the prevailing morphological components, fibrocollagenous, vascular, or histiocytic, an arbitrary division into three main categories was made. A fourth group was defined to include those cases in which a fully developed storiform pattern was the dominant morphological feature. The majority (15 cases) of the lesions were of the fibrocollagenous variety. Lesions with an angiomatous component (vascular variety) were the next most common (41 cases). Thirteen of the tumors were of the histiocytic variety. Twenty tumors were of the storiform variety and fulfilled many of the microscopic criteria of dermatofibrosareoma protuberans. This latter group often presents a diagnostic problem and may stimulate fibrosarcoma, aggressive fibromatosis or other connective tissue neoplasias. The combination of several clinical and pathological features are helpful in better separating this variety from the more benign forms. The present of different well-defined morphological components developing in the same tumors suggests a common origin. [ABSTRACT FROM AUTHOR]