Ultrastructure of a fibroxanthosarcoma (malignant fibroxanthoma)

Abstract

Primary and metastatic lesions from a fibroxanthosarcoma (FXS) originating in the neck of a 29‐year‐old Caucasian woman are reported. Light and electron microscopic observations are correlated to define the various types of cells constituting this neoplasm. Ultrastructural examination verified that several types of cells can act as facultative fibroblasts. Since a malignant potentiality cannot be predicted solely from the histopathology of fibroxanthomas, an attempt was made to categorize certain ultrastructural nuclear and cytoplasmic organelles associated with FXS cells. This was done in order to further define the malignant neoplastic cells of the FXS, so that distinguishing the malignant from benign forms of this neoplasm may become more feasible.

An immunohistochemical study of differentiation in malignant fibrous histiocytoma

“…studies were aimed at establishing the origin of malignant fibrous histiocytoma either from a common progenitor cell of presumed macrophage and fibroblastic lineage, or from neoplastic histiocytes. In favour of the former hypothesis were several ultrastructural studies showing similarities between the histiocyte-and fibroblast-like cell types in malignant fibrous histiocytoma (Merkow et al 1971) and the occurrence of scattered small undifferentiated cells, thought to be stem cells, within many tumours (Fu et al 1975). The more prominent hypothesis, however, has been that most malignant fibrous histiocytomas are of histiocyte origin.…”

The Rise and Fall of Malignant Fibrous Histiocytoma

“…Ultrastructural studies of many cases of MFH, notably the common storiform-pleomorphic subtype, were published in these 2 decades to identify the cell types composing the sarcomas and establish their histogenesis [15][16][17][18][19][20][21][22][23][24]. The following cell types were identified: spindly fibroblastic cells with a prominent rough endoplasmic reticulum (RER); myofibroblasts with RER cisternae and peripheral arrays of actin myofilaments; histiocytic (histiocyte-like) plump cells containing lysosomes, lipid droplets, occasional hyaline globules, and surface pseudopodia; intermediate-type cells with features of both fibroblasts and histiocytes; undifferentiated (primitive mesenchymal) tumor cells with a scanty cytoplasm containing few organelles; histiocyte-like multinucleate tumor giant cells with short RER cisternae, lysosomes, lipid and filopodia; and xanthomatous cells that have numerous membrane-bound lipid droplets.…”

Malignant fibrous histiocytoma following radiation therapy of fibrous dysplasia

“…The histiogenesis is controversial but, on the basis of morphological studies and tissue culture experiments [2,3], it was originally postulated that the tumour arose from histiocytes which could become facultative fibroblasts. This concept was questioned by Fu et al, and Weiss and Enzinger, [4,5] and many now regard the tumour as developing from primitive mesenchymal cells which may show differentiation characteristics of histiocytes.…”