Malignant fibrous histiocytoma: a "fibrohistiocytic" or primitive, fibroblastic sarcoma

Das maligne fibr�se Histiozytom

The entity and nosology of pleomorphic malignant fibrous histiocytoma (MFH) is still ambiguous. The actual WHO-Classification uses pleomorphic malignant fibrous histiocytoma (MFH) and pleomorphic sarcoma NOS (not otherwise specified) synonymously. On the other hand text and illustrations convey the impression, that these tumors also could be pleomorphic lipo-, leio- or rhabdomyosarcomas etc. It would have been more informative to emphasize, that with the above mentioned specific sarcoma types MFH-like appearance may occur. Furthermore it would have been more up to date to consider pleomorphic sarcomas NOS as pleomorphic fibrosarcomas and include them in the chapter of fibroblastic and myofibroblastic tumors. This concept already has been carried out for the former myxoid variant of MFH, nowadays preferentially called myxofibrosarcoma. There is controversial discussion about the clinical significance of exact typing of pleomorphic sarcomas. Problems may also occur due to the lack of standards, which degree of desmin expression signifies leiomyosarcoma or just indicates myofibroblasts in MFH. The requirement of exclusion of other tumor-types before diagnosing pleomorphic fibrosarcoma still remains obligatory. After verification of the diagnosis pleomorphic sarcoma NOS or pleomorphic fibrosarcoma, grading e.g. according to criteria of the FFCCS can be carried out. Most cases of pleomorphic fibrosarcoma will qualify as high grade malignant.

Pathologic and prognostic characteristics of splenomegaly in dogs due to fibrohistiocytic nodules: 98 cases

Ninety-eight canine splenectomy specimens consisting of combined nodular lymphoid and fibrohistiocytic cell proliferation were evaluated for seven light microscopic characteristics. Electron microscopic features in eight primary and two metastatic nodules (liver) were also evaluated. Nodular fibrohistiocytic proliferation in the canine spleen is characterized by a mixed population of histiocytoid and/or spindle cells in varying proportions intermixed with hematopoietic elements, plasma cells, and/or lymphocytes. These nodules seem to form a continuum between splenic lymphoid nodular hyperplasia and malignant splenic stromal neoplasms (malignant fibrous histiocytoma). Immunohistochemical methods used on 32/98 specimens showed uniform and strong positive staining among fibrohisiocytic cells for vimentin and desmin; S100 protein was similarly stained in general abundance. Individual cells strongly stained with smooth muscle actin were sparse but widely distributed. Proliferating cell nuclear antigen was not useful in the subjective differentiation of nodules taken from dogs that died of spleen-related causes and those surviving 12 months following splenectomy. A spectrum of cell types were observed by electron microscopy within each nodule. Fibroblasts, macrophages, intermediate fibrohistiocytic types, and several forms of splenic reticular cells were present. There were no consistent alterations in hematology or serum chemistry profiles of these dogs to provide useful diagnostic/prognostic information. Among the 93/98 dogs with complete (12 month) follow-up information, 48% (45/93) were alive and 52% (48/93) were dead. Dogs that died or were euthanatized during the follow-up period had a median survival of 5 and 5.5 months, respectively (range 0-15 months). Forty-four percent (21/48) died from causes linked to their splenic disease, and 35% (17/48) died from competing causes. The cause of death in 21% (10/48) was unknown. Lymphoid:fibrohistiocytic proportion and mitotic index in the nodules were anatomic features most predictive of postplenectomy mortality. A higher proportion of lymphoid to fibrohistiocytic type cells was associated with increased long-term survival, whereas lower lymphoid:fibrohistiocytic proportions and higher mitotic index indicated a probability of higher short-term mortality.

Malignant fibrous histiocytoma of the stomach during pregnancy: a case report

In this case report we describe a patient with a primary malignant fibrous histiocytoma of the stomach, diagnosed and operated upon during the sixth month of pregnancy. We stress the importance of a thorough diagnostic examination in cases of severe anaemia during pregnancy. Although very rare, malignancy of the gastrointestinal tract should be taken in consideration. No holding back is justified in diagnostic and therapeutic measurements because of pregnancy. Radiologic examination of the gastrointestinal tract should be replaced by endoscopy.

Giant malignant fibrous histiocytoma of the testis/spermatic cord: psychologic and possible etiologic complications of unethical Nazi medical experimentation

This case of malignant fibrous histiocytoma of the testis/spermatic cord was found in a Holocaust survivor who was injected with an unknown substance in the left testicle while in Auschwitz concentration camp in 1943. Because malignant fibrous histiocytoma is a neoplasm rarely found in this location, with only 26 previously reported cases, a review of this entity was performed. A review of Nazi medical practices in the literature and through the Holocaust Museum research department was undertaken in an attempt to ascertain identification of the unknown substance injected into this patient; however, exact identification of the Auschwitz experiment or experimenter could not be determined. A left radical orchiectomy was performed, and subsequent histolopathologic review revealed a well-encapsulated 27 x 22 x 17-cm malignant fibrous histiocytoma. The left testis was not clearly identified due to necrosis of the tumor. This is the largest malignant fibrous histiocytoma of the spermatic cord/testis recorded in the literature to date. Based on the unusual location and size, the intratesticular injection probably contributed to the tumor development and certainly caused the patient's delay in seeking medical treatment.

Differential diagnosis of malignant tumours in the abdominal cavity of rats after intraperitoneal injection of crocidolite or benzo[a]pyrene

In our investigation (i.p. test), crocidolite and benzo[a]pyrene, both caused a progression from initially reactive, then autonomously transformed proliferation of myofibroblasts and undifferentiated mesenchymal cells to malignant, multidirectionally differentiated (desmin and ED-1 positive) fibro-histiocytic tumours. Immunohistochemically these tumours showed no morphological characteristics (for example co-expression of vimentin and keratin in spindle-shaped tumour cells) of human asbestos-associated malignant mesotheliomas. On the other hand many tumour cells induced by crocidolite and benzo[a]pyrene had an ultrastructural appearance resembling fibroblasts and myofibroblasts. These have been demonstrated in only a few desmoplastic and sarcomatous mesotheliomas in human beings. None of the tumours revealed the typical ultrastructural features of epitheloid or transitional mesotheliomas. Apparently, both carcinogenic substances induce the transformation of undifferentiated pluripotent mesenchymal cells in rat peritoneum, regardless of their localization in the submesothelial compartment or perivascular connective tissue (preferentially after crocidolite application) or in the connective tissue pseudocapsule of major benzo[a]pyrene containing beeswax/tricaprylin depots in the mesometrium and mesenterial fatty tissue. In this way asbestos fibres in this animal experiment do not seem to induce an arrest in differentiation of intermediate or immature mesothelial cells as supposed formerly, but rather affect undifferentiated mesenchyme cells and myofibroblasts. This is an explanation for the immunohistochemical expression of markers of muscular differentiation in these tumour cells, which is known to occur in human malignant fibro-histiocytic tumours. If supplementary immunohistochemical investigations with different keratin antibodies also fail to confirm the mesothelial differentiation of the tumours induced in our i.p. test, the decision to call them "mesotheliomas" should be reconsidered. Further immuno-transmission-electron microscopical investigations with intermediate filament or macrophage antibodies are needed to clarify whether the term malignant "fibrohistiocytic sarcoma", "mesenchymoma" or "mesothelioblastoma" would be more correct from the morphological point of view.