Benign Fibrous Histiocytoma of the Renal Capsule

The first case of benign fibrous histiocytoma of the renal capsule is reported in a male aged 44 years. The tumor had its point of origin in the renal capsule. Histologically, the tumor was composed of intersecting fascicles of fibro-blastic cells forming a loose crisscross or "storiform" pattern. Electron microscopic studies of tumor cells revealed intermediate filaments and membrane-bound collagen fibers which continued to extracellular collagen bundles. This deep-seated fibrous histiocytoma had a more prominent storiform pattern and fewer secondary elements such as xanthoma cells than cutaneous ones. Acta Pathol Jpn 42: 217 220, 1992.     

Experimental approach to fibrous histiocytoma

A transplantable tumor was produced in syngeneic mice inoculated with transformed bone marrow macrophages (28-12- and L-18 cell lines). The tumor composed of proliferative spindle cells was arranged in a storiform pattern, and was similar to that of human fibrous histiocytoma. Electron microscopically, the tumorous spindle cells had fibroblastic characteristics, while functionally, the tumor cells had histiocytic characteristics, and consisted of a transitional form between histiocytes and fibroblasts. We consider the spindle cells to be facultative fibroblasts. This finding is compatible with the hypothesis that fibrous histiocytoma is derived from histiocytes.     

EXPERIMENTAL APPROACH TO FIBROUS HISTIOCYTOMA

A transplantable tumor was produced in syngeneic mice inoculated with transformed bone marrow macrophages (28–12– and L-18 cell lines). The tumor composed of proliferative spindle cells was arranged in a storiform pattern, and was similar to that of human fibrous histiocytoma. Electron microscopically, the tumorous spindle cells had fibroblastic characteristics, while functionally, the tumor cells had histiocytic characteristics, and consisted of a transitional form between histiocytes and fibroblasts. We consider the spindle cells to be facultative fibroblasts. This Anding is compatible with the hypothesis that fibrous histiocytoma is derived from histiocytes.     

Malignant theca cell tumor of rat

A large-sized ovarian tumor of theca cell origin was found in a female rat. The mass was located in the right ovary position. Histologically, the tumor was covered by thin fibrous capsule and consisted of a solid area and an abundant necrotic area. Tumor cells were arranged in a storiform or whorled pattern. Connective tissue elements occasionally presented as bundles of dense collagen fibers. Fusiform to elongated cells had oval- to spindle-shaped nuclei with indistinct nucleoli. Large round nuclei and mitotic figures were scattered throughout the tumor cells. These cells were stained positively with S-100 but negatively with vimentin and a-smooth muscle actin. Tumor cells with abundant cytoplasm sometimes contained multiple small-sized lipid vacuoles.     

Malignant Fibrous Histiocytoma with Epithelial Differentiation?

A case of recurrent soft part sarcoma with focal areas showing epithelial differentiation in the right thigh in a 78-year-old woman is reported. The primary tumor consisted of myxoid areas and solid areas, in which relatively uniform epithelioid tumor cells were arranged in sheets, whereas pleomor-phism and a storiform pattern appeared in the recurrent tumors. Thus this tumor was suspected to be a malignant fibrous histiocytoma. However, further studies showed unexpected ultrastructural and immunohistochemical features. Cytokeratin immu-noreactivity and tonofilamentlike structures probably indicated epithelial differentiation of some tumor cells. From the clinical and histological findings, this tumor should be identified as a malignant fibrous histiocytoma with phenotypic expressions of epithelial cell.     

Acute Myopathy Associated with Chronic Licorice Ingestion: Reversible Loss of Myoadenylate Deaminase Activity

A case of recurrent soft part sarcoma with focal areas showing epithelial differentiation in the right thigh in a 78-year-old woman is reported. The primary tumor consisted of myxoid areas and solid areas, in which relatively uniform epithelioid tumor cells were arranged in sheets, whereas pleomor-phism and a storiform pattern appeared in the recurrent tumors. Thus this tumor was suspected to be a malignant fibrous histiocytoma. However, further studies showed unexpected ultrastructural and immunohistochemical features. Cytokeratin immu-noreactivity and tonofilamentlike structures probably indicated epithelial differentiation of some tumor cells. From the clinical and histological findings, this tumor should be identified as a malignant fibrous histiocytoma with phenotypic expressions of epithelial cell.     

A tumor composed of myofibroblasts: an ultrastructural study

A subcutaneous tumor of the right temporal region of head was removed from an 8-year-old boy. This tumor was studied by light and electron microscopy. He was found to have had a retroperitoneal inflammatory fibrous histiocytoma which had been excised seven years ago. The subcutaneous tumor histologically consisted of spindle cells in fascicles, which did not arrange in a storiform or herring-bone pattern. Electron microscopically, this tumor was chiefly composed od myofibroblasts. electron microscopy is essential to determine the cell types of a tumor and we have classified this tumor as a tumor of myofibroblasts. The relationship between the retroperitoneal tumor and the head tumor was discussed.     

A TUMOR COMPOSED OF MYOFIBROBLASTS An Ultrastructural Study

A subcutaneous tumor of the right temporal region of head was removed from an 8-year-old boy. This tumor was studied by light and electron microscopy. He was found to have had a retroperitoneal inflammatory fibrous histiocytoma which had been excised seven years ago. The subcutaneous tumor histologically consisted of spindle cells in fascicles, which did not arrange in a storiform or herring-bone pattern. Electron microscopically, this tumor was chiefly composed of myofibroblasts. Electron microscopy is essential to determine the cell types of a tumor and we have classified this tumor as a tumor of myofibroblasts. The relationship between the retroperitoneal tumor and the head tumor was discussed.     

Malignant fibrous histiocytoma of bone. Clinical pathology and histological diagnosis

Malignant fibrous histiocytoma of bone is a histologically well-defined tumor. Our aim is to describe five own cases and to analyze the published cases in order to demonstrate, the controversial aspects of clinical pathology. The essential histological criteria are the storiform tissue pattern and the presence of fibroblastic and histiocytic cells and giant cells. Inclusive of our cases, the total number reported stands at 196. There are features of malignant fibrous histiocytoma of bone about which there is almost general agreement: 1. The tumor occurs at all ages with an average onset from the age of 10 to the age of 50. 2. The tumor occurs in both the long and flat bones, but the main sites are the distal femur and the proximal tibia. 3. The tumor lacks any initial distinctive features in its clinical phase, but with respect to its biological behaviour, malignant fibrous histiocytoma of bone can be distinguished from osteosarcoma.     

Cellular differentiation in storiform-pleomorphic malignant fibrous histiocytomas. An electron microscopic study of histogenesis

The most common form of malignant fibrous histiocytoma is the storiform-pleomorphic subtype composed of spindle-shaped fibroblast-like cells, mononucleated histiocytic elements and a changing amount of pleomorphic giant cells. In relation to the changing cellular structures 14 pleomorphic-storiform malignant fibrous histiocytomas were investigated electronmicroscopically. In all tumors several types of cells varying in shape, and size as well as in organelle composition could be demonstrated: 1. Undifferentiated cells, which are relatively small and have a scanty cytoplasm with few organelles. 2. Fibroblast-like cells with well developed rough endoplasmic reticulum, mostly arranged in a storiform pattern. 3. Myofibroblasts corresponding to fibroblasts and showing bundles of thin filaments (4 to 6 nm) with focal dense bodies in the peripheral area of the cytoplasm. 4. Histiocyte-like cells characterized by filopodia-like projections and abundant cytoplasm containing lysosomes and phagolysosomes and also lipid droplets. 5. Chimeric cells, which are intermediate forms with features of fibroblast-like and histiocyte-like tumor cells. 6. Multinucleated tumor giant cells which can be subdivided into fibroblast-like and histiocyte-like types and intermediate forms. On the basis of our ultrastructural studies the storiform pleomorphic malignant fibrous histiocytoma is interpreted as a tumor of an undifferentiated mesenchymal cell with the potency of fibroblastic or histiocytic differentiation. The origin of this cell is uncertain. Dedifferentiation of a differentiated connective tissue cell (fibroblast, pericyte) into a proliferating undifferentiated precursor cell is discussed.     

Intrasellar pituicytoma in a patient with other endocrine neoplasms

Considered a neoplasm of pituicytes, pituicytoma is a rare and distinct type of glioma that arises in the suprasellar space and within the sella turcica. Only 12 previously reported cases of pituicytoma are documented in the literature. We report an intrasellar pituicytoma in a 66-year-old man presenting with symptoms and radiologic appearance indistinguishable from a nonfunctional pituitary adenoma. The patient also had a medical history significant for parathyroid adenomas and follicular carcinoma of the thyroid. The intrasellar tumor had morphologic features of a pituicytoma, with interlacing fascicles and a storiform pattern much like a benign fibrous histiocytoma. Immunoreactivity for S100 was strong, but the tumor lacked intercellular collagen type IV. The differential diagnosis of a low-grade spindle cell lesion of the sellar space is discussed, and the literature is reviewed. A summary of the clinical and pathologic features of this case, as well as the 12 previously reported cases, is presented.     

Primary malignant fibrous histiocytoma of the liver—a case report with immunocytochemical observations

A case of a primary sarcomatous tumour in the liver of an elderly female is reported. The tumour consisted of bundles of spindle cells focally in a storiform pattern, intermingled with bizarre giant cells. Immunocytochemically, carcinoembryonic antigen, alpha-fetoprotein, keratin, desmin and type IV collagen could not be demonstrated. Most tumour cells, however, expressed vimentin, whereas a granular cytoplasmic immunoreactivity for alpha-1-antitrypsin and alpha-1-antichymotrypsin was shown in the giant cells. Ultrastructurally the tumour cells did not show any characteristics of epithelial derivation. The morphological and immunocytochemical data justify the conclusion that the tumour should be classified as a malignant fibrous histiocytoma.     

Malignant fibrous histiocytoma of the lung

Summary A case of malignant fibrous histiocytoma of the lung is reported. The tumour margin was well circumscribed, showing an expanding border and no capsule. The main part of the tumour was composed of spindle-shaped fibroblast-like cells arranged in broad fascicles with a partially storiform pattern. Other parts of the tumour were arranged in a haphazard pattern, containing many mononucleated and multinucleated giant cells. Ultrastructurally six differnt cell types were encountered. The dominant type was a fibroblast-like cell; also present were many giant cells and some histiocyte-like cells, together with their intermediate forms, and few undifferentiated mesenchymal cells. We consider this tumour to have developed from the peribronchial connective tissue; it has the same cellular composition as the malignant counterpart arising in soft tissues.     

Malignant peripheral nerve sheath tumor with perineurial cell differentiation (malignant perineurioma)

A unique case of malignant peripheral nerve sheath tumor (MPNST) with perineurial cell differentiation occurring in a 63-year-old woman in a subcutis of the forearm is described. The tumor contained cellular and myxoid areas. The neoplastic cells were fusiform with distinct cell borders. They were arranged in storiform pattern and in wavy parallel cell cords in the cellular areas. Focally, a pleomorphism and mitotic activity (including atypical mitoses) similar to those of malignant fibrous histiocytoma were seen. The myxoid parts contained haphazardly oriented cells and scarce lipoblast-like multivacuolated cells mimicking a liposarcoma. In the differential diagnosis, myxoid liposarcoma, dermatofibrosarcoma protuberans, malignant fibrous histiocytoma and low-grade fibromyxoid sarcoma were considered. Immunohistochemically, perineurial differentiation was indicated by the diffuse expression of epithelial membrane antigen and focal reactivity for CD34. The tumor was negative with antibodies to S-100 protein, Leu-7, CD68 (KP1), vimentin and cytokeratin AE1/AE3. Ultrastructure of tumor cells revealed features of MPNST. No recurrence occurred in the patient during 2 years follow up.     

Xanthogranuloma of the rectum

A 46-year-old man with a suspected malignant submucosal tumor received a transabdominoperineal rectal amputation. The histologic diagnosis was xanthogranuloma. The differentiation of xanthogranuloma from malignant fibrous histiocytoma and other histiocytic tumors is difficult in the preoperative stage. Malignant fibrous histiocytoma can be diagnosed histologically by the presence of pleomorphism, mitotic activity, hyperchromatism, and a storiform pattern of cell arrangement. Moreover, some xanthogranulomas are also thought to have malignant potentiality and surgical resection is regarded as the preferred treatment. As for prognosis, the patient has lived for three years after the operation but further follow-up is thought to be necessary.     

Reactive fibrohistiocytic proliferation simulating fibrous histiocytoma

A pelvic nodule was excised at the time of reexploration of the abdomen in a 32-year-old women who had previously had a malignant germ cell tumor with a mixed histologic pattern of the right ovary. The 3-cm firm lesion from the right vaginal apex was composed predominantly of spindle cells with a prominent storiform pattern. Some findings, such as the presence of foamy histiocytes and a focal foreign body reaction with polarizable material, were atypical for a lesion otherwise quite acceptable histologically as a fibrous histiocytoma. Ultrastructural findings also tended to support the reactive rather than neoplastic nature of this mass. There is a similarity to the silica reaction described by Weiss and co-workers (Cancer 42:2738-2743, 1978).     

XANTHOGRANULOMA OF THE RECTUM

A 46-year-old man with a suspected malignant submucosal tumor received a transabdominoperineal rectal amputation. The histologic diagnosis was xanthogranuloma. The differentiation of xanthogranuloma from malignant fibrous histiocytoma and other histiocytic tumors is difficult in the preoperative stage. Malignant fibrous histiocytoma can be diagnosed histologically by the presence of pleomorphism, mitotic activity, hyperchromatism, and a storiform pattern of cell arrangement. Moreover, some xanthogranulomas are also thought to have malignant potentiality and surgical resection is regarded as the preferred treatment. As for prognosis, the patient has lived for three years after the operation but further follow-up is thought to be necessary.     

FIBROUS HISTIOCYTOMA OF THE NASAL CAVITY AND MAXILLARY SINUS

Two cases of fibrous histiocytoma were presented; Case 1: a 46-year-old man with a tumor filling the left nasal cavity and maxillary sinus, and Case 2: an 80-year-old man with a tumor of the right maxillary sinus destroying its surrounding wall. Histologically, the former was dominated by storiform pattern and onion-like structures, and the latter by osteoclast-like multinucleated giant cells. After radical surgery, Case 1 was free of recurrence for more than one year, and Case 2 showed recurrence although still maintaining fairly good health. A total of 29 cases hitherto reported arising in the nasal, paranasal and nasopharyngeal regions were reviewed, pitfall of differential diagnoses was commented especially in our two cases, criteria of malignancy were discussed, and the necessity of repeated samplings was emphasized because of paucity and unfamiliarity of fibrous histiocytoma arising, in particular, from the upper respiratory tract.     

Fibrous histiocytoma of the nasal cavity and maxillary sinus

Two cases of fibrous histiocytoma were presented; Case 1: a 46-year-old man with a tumor filling the left nasal cavity and maxillary sinus, and Case 2: an 80-year-old man with a tumor of the right maxillary sinus destroying its surrounding wall. Histologically, the former was dominated by storiform pattern and onion-like structures, and the latter by osteoclast-like multinucleated giant cells. After radical surgery, Case 1 was free of recurrence for more than one year, and Case 2 showed recurrence although still maintaining fairly good health. A total of 29 cases hitherto reported arising in the nasal, paranasal and nasopharyngeal regions were reviewed, pitfall of differential diagnoses was commented especially in our two cases, criteria of malignancy were discussed, and the necessity of repeated samplings was emphasized because of paucity and unfamiliarity of fibrous histiocytoma arising, in particular, from the upper respiratory tract.     

Malignant fibrous histiocytoma of the renal capsule

Summary This light microscopically pleomorphic tumor, which occurred in the renal capsule of 35-year-old female was diagnosed as a malignant fibrous histiocytoma. Ultrastructurally, the tumor showed two major components; fibroblast-like and histiocyte-like cells. This report stresses the rarity of such neoplasm in the kidney and also the usefulness of electron microscopy in establishing the diagnosis.