Characterization of tumour cells in malignant fibrous histiocytomas and other soft tissue tumours in comparison with malignant histiocytes. I. Immunohistochemical study on paraffin sections

Absence of Expression of c-sis and Transforming Growth Factor-β mRNA in Malignant Fibrous Histiocytoma

Total RNA was extracted from five malignant fibrous histiocytomas and two benign fibrohistiocytic lesions and assayed for mRNA expressions for transforming growth factor beta (TGF-β) and c-sis by Northern blot analysis. Production of both of these has been associated with cells of monocyte-macrophage lineage, and these factors have been shown to be important in physiologic mesenchymal cell proliferation. No mRNA expression of either TGF-β or c-sis was identified in any of the fibrohistiocytic tumor samples. The lack of expression of TGF-β and c-sis may be consistent with a nonhistiocytic origin of malignant fibrous histiocytoma, or may reflect transformation- associated loss of the normal molecular mechanisms of mesenchymal proliferation. The absence of c-sis mRNA expression can be reconciled with the prior immunohisto chemical demonstration of platelet-derived growth factor in tumor cells of malignant fibrous histiocytoma. Int J Surg Pathol(2):117-122, 1993

An approach to pleomorphic sarcomas: can we subclassify, and does it matter?

The term malignant fibrous histiocytoma (MFH) has been supplanted by undifferentiated pleomorphic sarcoma (UPS). Even now, however, a number of pleomorphic neoplasms are classified as UPSs when in fact at least a subgroup of these can be more precisely classified as a pleomorphic sarcoma with a specific line of differentiation. Still others are pseudosarcomas, most commonly sarcomatoid carcinomas. This review will discuss historical aspects of MFH/UPS as well as provide an approach to the pleomorphic malignant neoplasm with a discussion of useful ancillary techniques in the evaluation of such cases.

Casual discovery of a thoracic tumour showing histological features of undifferentiated pleomorphic sarcoma in a male Wistar laboratory rat

Sarcomas are neoplasms of mesenchymal origin, with a predominant cell population mimicking the organization of various soft tissues and/or bones. Previous categorizations also included the possibility of the presence of tissue macrophage-like (histiocytes) neoplasm cells, in a tumour described as malignant fibrous histiocytoma, but this group has been considered as a variety of undifferentiated pleomorphic sarcomas. Although this kind of malignancy is not rare in humans, only few cases have been reported in laboratory animals. We report an unusual single case of spontaneous tumour growth, detected by casual observation, in the left thoracic area of an 18-month-old male laboratory Wistar rat. Both this individual and his ancestors were not exposed to any known carcinogenic substance or radiation, thus suggesting the development of the neoplasm as a spontaneous event. The mass was extracted surgically under general anaesthesia, and slices were examined histologically and immunohistochemically, using photon microscopy. The pathologist reported the presence of a combination of fibroblasts and undifferentiated mesenchymal cells arranged in a storiform pattern. Immunohistochemistry was performed on the tissue using specific antibodies for several proliferation (Ki-67) and differentiation (S-100, CD-34, CD-68, pan-keratin, desmin and smooth muscle actin-SMA) markers. Positive reaction was observed for S-100, Ki-67, CD-68, desmin and SMA (limited) but not for CD-34 or cytokeratin.

Cytomorphological study of soft tissue neoplasms: role of fluorescent immunocytochemistry in diagnosis

OBJECTIVES

Exact categorization of soft tissue tumours (STTs) on smears requires application of various ancillary techniques. This study was aimed at evaluating the role of fluorescent immunocytochemistry (FICC) in cyto-diagnosis of 30 STT cases.

METHODS

Thirty cases of soft tissue tumours were included in the present study. All cases were subjected to routine Giemsa and Papanicolaou stain. Extra smears were made and kept for fluorescent immunostaining. A panel of cytoskeletal antibodies, tagged with FITC (Fluorescein isothyocynate), was employed in all these cases. Fluorescent immunostained smears were examined under Zeiss Confocal Laser scanning microscope, using double immunofluorescence (red-green). Finally, all cases were subjected to biopsy and again immunoperoxidase staining.

RESULTS

Among the 30 cases in the present study, unaided cytological diagnoses ranged from 'spindle cell' tumour in four (13.3%) cases, benign and malignant spindle cell tumour in 17 (56.6%) cases, to malignant mesenchymal tumour in nine (30%) cases. FICC helped in further correct categorization of 25/30 (83.3%) cases viz. leiomyoma (three), benign neurogenic tumour (six), schwannoma (one), dermatofibrosarcoma protuberans (three), synovial sarcoma (two), rhabdomyosarcoma (two), malignant fibrous histiocytoma (five) and malignant peripheral nerve sheath tumour (three). Aggressive fibromatosis was found to be a missed diagnosis in two cases. Overall concordance between cyto-diagnosis with FICC, and histopathology results was 83.3% (P < 0.05).

CONCLUSION

Fluorescent immunocytochemistry is a significant ancillary technique for making a rapid and specific diagnosis of STT, as required for their timely management. Incorporation of a wide panel of antibody markers with clinico-cytological correlation is recommended in forming an exact diagnosis in these cases.

Histiocytic sarcoma: a study of five cases including the histiocyte marker CD163

Histiocytic sarcoma (HS) is a rare but controversial hematopoietic neoplasm. In the past, malignancies have been misclassified as histiocytic tumors due to overlapping histologic features and inadequate phenotypic data. CD163, a recently characterized hemoglobin scavenger receptor, appears to be a 'specific' marker of histiocytic lineage and a promising diagnostic tool for evaluating histiocytic neoplasms. Five cases of HS were studied to further elucidate the clinicopathologic features of these rare tumors and to demonstrate the diagnostic utility of CD163. Criteria for diagnosis included histologic and immunohistochemical evidence of histiocytic differentiation, CD45 positivity, and exclusion of lymphoid, epithelial, melanocytic and dendritic cell phenotype. Sites of disease included the colon (two cases), palate, inguinal lymph node, and testis. The clinical course was aggressive in 4/5 patients (survival=2-15 months). One patient with localized disease of the palate, survived 17 years after diagnosis. All patients with poor survival had tumors > or =3.5 cm. Histologically, all cases showed diffuse architecture with large, discohesive polygonal cells. Spindling of cells was focally noted. Hemophagocytosis was identified in 3/5 cases. A prominent inflammatory background was present in 4/5 tumors. All cases were immunoreactive for CD45, CD163, CD68, and lysozyme. S-100 was focally positive in 4/5 cases. Antibodies for melanocytic, epithelial, lymphoid, and dendritic cell markers were negative. Molecular studies showed monoclonal IgH gene rearrangements in three cases. Our findings suggest that HS is an uncommon neoplasm frequently extranodal in presentation and aggressive in behavior, with rare exceptions. Stage of disease and possibly tumor size are significant prognostic indicators. Molecular studies remain controversial in the diagnosis. The morphologic and phenotypic features are relatively uniform; however, the diagnosis requires exclusion of more common neoplasms by extensive immunophenotypic studies. CD163 appears to be a specific histiocytic marker and is important in establishing the diagnosis of HS.

Canine transmissible venereal tumour: Cytogenetic origin, immunophenotype, and immunobiology. A review

Canine transmissible venereal tumour (CTVT) is the only known naturally occurring tumour that can be transplanted as an allograft across major histocompatibility (MHC) barriers within the same species, and even to other members of the canine family, such as foxes, coyotes and wolves. The progression of this tumour is unique in that, it follows a predictable growth pattern. In natural and experimental cases, the growth pattern includes progressive growth phase, static phase and regression phase, and this is followed by transplantation immunity in immunocompetent adults, while metastasis occurs in puppies and immunosuppressed dogs. Because of the uniqueness of CTVT transmission and progression, experimental investigations of various aspects of the biology of CTVT have been used to provide clues to the immunobiology of both animal and human tumours. This review examines the current state of knowledge of the aspects of the cytogenetic origin, immunophenotype, immunobiology and immunotherapy of CTVT.

Characterization of four cell lines derived from a human malignant fibrous histiocytoma of the maxillary sinus

We have established four cell lines from a human malignant fibrous histiocytoma. Each cell line had human aneuploid karyotype and DNA aneuploidy. Cells in all lines expressed CD13, CD68 and vimentin but lacked CD11, CD14, CD15, CD16, CD45, HLA class II and other mesenchymal and epithelial markers such as desmin, alpha-smooth muscle, myoglobin, S-100 protein, and cytokeratin. None of the cells expressed surface IgG or C3 receptor, nor did any of them phagocytose latex particles. The cells reacted with an antibody for prolyl-4-hydroxylase, but no collagen (types I, II, III, or IV) was detected in any of the cell lines. The homogenates of all cell lines had cyclic nucleotide phosphodiesterase 3 activity. Two cell lines produced granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-1alpha, IL-6 and tumor necrosis factor alpha, another line produced G-CSF, IL-1alpha, IL-6 and platelet-derived growth factor (PDGF)-AB, and the remaining cell line produced only PDGF-AB. None of the cells produced transforming growth factor-alpha. The results indicated that the cell lines were immunophenotypically similar to primitive mesenchymal cells.

Malignant fibrous histiocytoma of the cecum: report of a case and review of the literature

Malignant fibrous histiocytoma (MFH) of the gastrointestinal tract is extremely rare. Here we report a case of MFH of the cecum and review other cases of large bowel MFH in the literature. A 64-year-old man had a large tumor mass in the cecum associated with multiple small peritoneal implants. Histologically, most of the lesion showed inflammatory pseudotumor-like appearance; that is, a mixed proliferation of fibroblasts and myofibroblasts loosely arranged in sweeping fascicles or whorled structures and an admixture of chronic inflammatory cell infiltrate. The myofibroblastic nature of the spindle-shaped cells was confirmed by their immunohistochemical and ultrastructural findings. In addition, there was atypical histiocytic cells infiltrate in some areas and marked lymphatic involvement and lymph node metastasis by such histiocytic cells. These features were interpreted as MFH, although it had to be distinguished from inflammatory fibrosarcoma and leiomyosarcoma. The differential diagnosis is discussed here.

LN-2 (CD74). A marker to distinguish atypical fibroxanthoma from malignant fibrous histiocytoma

BACKGROUND

In this study, the authors examined the expression of LN-2, an antigen expressed by B cells, macrophages, and Reed-Sternberg cells, in a variety of spindle cell lesions of the skin to determine whether LN-2 immunoreactivity can be used to differentiate among these tumors. For comparison, they examined CD34 antigen expression in these lesions, which has been shown to be a useful marker in differentiating dermatofibrosarcoma protuberans from dermatofibroma.

METHODS

Immunocytochemistry with anti-LN-2 and anti-CD34 monoclonal antibodies on formalin fixed, paraffin embedded material was performed on 102 spindle cell lesions, including dermatofibroma, dermatofibrosarcoma protuberans, atypical fibroxanthoma, malignant fibrous histiocytoma, leiomyoma, and neurofibroma.

RESULTS

LN-2 immunoreactivity did not distinguish between dermatofibroma and dermatofibrosarcoma protuberans, both of which showed weak immunoreactivity. In marked contrast, 90% of cases of malignant fibrous histiocytoma showed strong staining for LN-2, whereas the vast majority (90%) of cases of atypical fibroxanthoma were negative or stained only weakly with anti-LN-2 antibodies. Of the two cases of atypical fibroxanthoma that stained strongly for LN-2, both lesions were > 2 cm in size and extended deep into the subcutaneous fat.

CONCLUSIONS

Differential expression of the LN-2 antigen by atypical fibroxanthoma and malignant fibrous histiocytoma distinguishes these two lesions and suggests that acquisition of LN-2 positivity may be a marker of tumor progression.

Malignant fibrous histiocytoma of the esophagus

A 78-year-old man presented with an esophageal polyp that was confirmed by immunohistochemistry and electron microscopy to be malignant fibrous histiocytoma. The tumor was comprised of a proliferation of spindle-shaped cells admixed with bizarre giant cells. These tumor cells were immunoreactive for smooth muscle actin, vimentin, alpha-1-anti-chymotrypsin and CD68. Electron microscopic examination revealed the myofibroblastic and histiocytic features of the tumor cells. No elements of epithelial or myogenic differentiation were found in the tumor. Malignant fibrous histiocytoma of the esophagus is extremely rare, with 10 cases being documented so far in the literature. The differential diagnosis of pleomorphic tumors of the esophagus is discussed.

Myxofibrosarcoma. Clinicopathologic analysis of 75 cases with emphasis on the low-grade variant

Myxofibrosarcoma is one of the most common sarcomas in the extremities of elderly patients. We analysed the clinicopathologic features in a series of 75 patients. All patients were adults (range, 22-91 years; median, 66 years) with an approximately equal incidence in men and women. Thirty-five tumors arose in the lower and 25 in the upper extremities, nine on the trunk, two each in the retroperitoneum and the head and neck region, and one each in the pelvis and penis. Forty-eight cases (69.5%) were located in dermal or subcutaneous tissues. Distinctive histologic features included the following: a commonly nodular growth pattern; a myxoid matrix containing elongated, curvilinear capillaries; and fusiform, round or stellate tumor cells with indistinct cell margins, slightly eosinophilic cytoplasm, and hyperchromatic atypical nuclei. These lesions varied from a hypocellular, mainly myxoid, and purely spindle-cell appearance (low-grade neoplasms) to high-grade, pleomorphic (malignant fibrous histiocytoma-like) lesions with multinucleated giant cells, high mitotic activity, and areas of necrosis. Immunohistochemistry in 44 cases revealed only vimentin and occasional actin positivity. Ultrastructurally, tumor cells had a fibroblastic phenotype. DNA flow cytometry and proliferation analysis showed an association between aneuploidy and histologic grade. An average follow-up of 45 months (range, 5-300 months) in 60 cases has revealed local recurrence in 33 cases (54%). Thirteen patients developed metastases, and 13 tumor-related deaths occurred. A short interval to first local recurrence was associated with poor clinical outcome. The rate of local recurrence was independent of histologic grade, but only intermediate and high-grade neoplasms metastasized. The depth of the primary lesion did not influence the incidence of local recurrence. However, in deep-seated neoplasms, the incidence of metastases was higher and the percentage of tumor-related deaths was twice as high as in superficially located lesions, reflecting the fact that deep-seated lesions tended to be higher-grade, larger tumors. Myxofibrosarcoma tends to become progressively higher grade in recurrences, as demonstrated in five cases in our series. The poorly recognized low-grade myxofibrosarcoma is emphasized, as proper diagnosis and treatment and scrupulous follow-up are mandatory to avoid local recurrence and gradual tumor progression to a higher-grade neoplasm that may then metastasize.

Establishment and characterization of transplantable tumor derived from a spontaneous malignant fibrous histiocytoma in the mouse

A tumor developed spontaneously in the subcutaneous tissue of the hind leg of a 7-month-old female ddY mouse. Light and electron microscopical examinations revealed that the original tumor was composed of an admixture of fibroblast-like and histiocyte-like cells arranged predominantly in a storiform or cartwheel pattern. The tumor cells gave positive reactions for acid phosphatase, N-acetyl-beta-glucosaminidase, non-specific esterase, beta-glucuronidase, alpha-1 antitrypsin and fibronectin. The original tumor was diagnosed as a malignant fibrous histiocytoma (MFH). The tumor was serially transplanted into syngeneic mice up to the 92nd generation. The tumor was also consistently transplanted into allogeneic mice of several inbred strains. The allogeneic mice used in the present study were strains having different H-2 haplotypes. During succeeding passages, transplanted tumors showed aberrant growth properties. The tumor transplanted into mice of inbred strains took well to back transplantation for mice of original strain and allotransplantation for other inbred strains. The pathological features of these transplantable tumors were basically similar to those of the original tumor. As mentioned above, a MFH developed spontaneously in the ddY mouse was consistently transplantable into both syngeneic and allogeneic mice.

Granulocytic sarcoma: an immunohistologic comparison with peripheral T-cell lymphoma in paraffin sections

In evaluating histologically malignant infiltrates in the skin, it is often challenging to distinguish granulocytic sarcoma (GS) from selected cases of peripheral T-cell lymphoma (PTCL). These lesions have clinical features in common, in addition to shared histologic attributes. These include similarity in dermal distribution and growth pattern, nuclear characteristics, propensity to recruit other inflammatory cell types, and production of matrical sclerosis. In order to determine if immunohistology could contribute to differential diagnosis in this setting, we analyzed 15 cases of mucocutaneous GS, and compared them with 11 cases of well-documented PTCL. Antibodies in the CD15, CD20, CD34, CD43, CD45, CD45RO, and CD68 groups were used, as well as anti-myeloperoxidase (anti-MPX), anti-lysozyme (anti-LYSO), Mac387, and MB2. Anti-LYSO and anti-MPX were sensitive and specific markers of GS, labeling 93% and 80% of GS cases, respectively, and no cases of PTCL. Anti-CD15 and MB2 were also specific for GS, but each labeled only 60% of GS cases. CD34, CD68, and Mac 387 were specific but insensitive markers of GS. CD43 and CD45 were not particularly useful discriminants, with each being seen in 93% of GS cases, but also 64% and 100% of cases of PTCL, respectively. CD45RO was specific for PTCL; it was present in 82% of PTCL cases and no GS cases. Thus, conjoint reactivity for CD43, CD45, MPX, and LYSO characterizes GS, and differs from the pattern of PTCL, which is characterized by reactivity for CD45 and CD45RO, occasional reactivity for CD43, and lack of other specified markers.

Immunohistochemical staining of feline malignant fibrous histiocytomas

Malignant fibrous histiocytoma was diagnosed in seven cats from biopsy specimens received at the University of Missouri Veterinary Medical Diagnostic Laboratory during a 4-year period from 1987-1991. Tissue blocks from formalin-fixed specimens were resectioned and stained for type I (AE1) and type II (AE3) cytokeratins, desmin, S100 protein, vimentin, and alpha 1-antitrypsin by the avidin biotin peroxidase complex method with diaminobenzidine (DAB) chromogen. None of the tumors stained positively for alpha 1-antitrypsin. Four of seven of the tumors had similar immunohistochemical staining results, with positive staining for type I and type II cytokeratins, desmin, S100 protein, and vimentin. Of the remaining three, one stained positively only for S100 protein and vimentin; one stained positively for vimentin only; and one was negative for all six antigens. Based only on immunohistochemical staining results, three of the tumors could possibly be reclassified: one as a melanoma, one as a probable fibrosarcoma, and one as unknown. These results also indicate that feline malignant fibrous histiocytomas show a diversity of intermediate filament expression, as do human tumors. Our results also do not support the theory that malignant fibrous histiocytomas are of histiocytic origin.

Disseminated malignant histiocytosis in a golden retriever: clinicopathologic, ultrastructural, and immunohistochemical findings

Diagnosis of malignant histiocytosis (MH), a disorder characterized by systemic proliferation of morphologically atypical histiocytes and their precursors, in an 8-year-old neutered female Golden Retriever was based on light and electron microscopic and immunohistochemical findings. Clinically, the dog presented with unilateral forelimb lameness. Eight days after surgical exploration of a swollen brachium, the dog developed sudden onset of posterior paresis, fecal and urinary incontinence, and a flaccid tail. Necropsy revealed infiltrative and nodular lesions in the right forelimb and regional lymph nodes, thoracic and abdominal cavities, and lumbar epidural space. Gross lesions were not found in the lungs or integument. Histopathologic examination showed infiltrates of atypical histiocytes in skeletal muscle, joint, and regional lymph nodes of the right forelimb; intercostal muscle; lung; liver; spleen; pancreas; kidneys; and spinal dura. Most tumor infiltrates were nodular and composed of loosely aggregated cells that were 10-30 microns in diameter with abundant eosinophilic to foamy cytoplasm, had central or eccentric nuclei, and were periodic acid-Schiff negative. Many binucleated cells, multinucleated giant cells, and mitotic figures were seen. Tumor cells contained phagocytosed erythrocytes, mononuclear cells, and some leukocytes. Ultrastructural features of tumor cells included cytoplasmic lipid droplets, lysosomes, and phagolysosomes. Immunohistochemical studies on paraffin-embedded sections showed positive reactivity to human T-cell Ag (clone UCHL-1) and for lysozyme, alpha-1-antitrypsin, and cathespin B. Polyclonal intracellular immunoglobulin reactivity and lectin binding (peanut, soybean, and wheat germ agglutinins and concanavalin A) were also demonstrated. Criteria for diagnosis of malignant histiocytic tumors and differential diagnosis are discussed.

Malignant fibrous histiocytomas in dogs and cats: an immunohistochemical study

Immunohistochemical staining was performed on seven canine and 10 feline soft tissue tumours histologically diagnosed as malignant fibrous histiocytomas (MFHs) or MFH-like tumours, and eight other histologically specified tumours (non-MFH). This was done to determine if commercially available antibodies that are used routinely in human diagnostic pathology for MFHs would express the same immunohistochemical patterns in canine and feline MFHs and MFH-like tumours. The antibodies were directed against human alpha 1-anti-trypsin (AT), human alpha 1-anti-chymotrypsin (ACT), human lysozyme, bovine S-100 protein and human desmin. AT did not show any immunoreactivity in the tissues investigated. Except for one MFH, all canine MFHs and other soft tissue tumours with a 'histiocytic' character stained for lysozyme and not for S-100. Six out of seven canine MFHs and MFH-like tumours stained positive for desmin as did most non-MFH sarcomas. Most of the canine and feline MFHs and MFH-like tumours were positive for ACT. These findings for ACT staining in canine and feline MFHs and MFH-like tumours are in agreement with the findings in human MFHs. The immunohistochemical results of canine MFHs and MFH-like tumours were different from those in cats. Feline MFHs differed from canine MFHs for both lysozyme and desmin staining.

Osteoclast-like giant cell tumour of the gallbladder

We describe a rare carcinoma of the gallbladder containing osteoclast-like giant cells. Well-differentiated adenocarcinoma was found in the mucosa of the fundus, and osteoclast-like giant cells were present mainly in a haemorrhagic mass protruding from the mucosal surface. The metastatic hepatic tumour was composed chiefly, if not exclusively, of osteoclastoma-like cells, but minute carcinomatous elements were also present. There was an apparent transition between the giant cells and tubular structures in both the gallbladder tumour and hepatic tumour. However, ultrastructural study did not reveal any evidence of epithelial differentiation in the giant cells. Immunohistochemical studies suggested that the mononuclear and giant cells were mesenchymal and histiocytic in nature (vimentin and factor XIIIa positive). A few exceptional giant cells transforming from the fine tubular structure were positive for epithelial membrane antigen. In conclusion, the osteoclast-like giant cell tumour component was thought to represent mesenchymal metaplasia in pre-existent adenocarcinoma.

Pathological and radiographical features of multicentric malignant fibrous histiocytoma in two dogs

Widespread organ distribution of malignant fibrous histiocytoma, including osseous involvement, was demonstrated in two dogs. Both cases had a storiform-pleomorphic pattern histologically and immunohistochemical stains were used to differentiate this from other types of neoplasms with the same histological pattern. Radiographically the lesions were predominantly lytic in the metaphysis of long bones, although periosteal proliferation and axial skeletal involvement were seen in one dog.

Usefulness of antikeratin immunoreactivity in osteosarcomas of the jaw

The immunohistochemical typing of cytoplasmic intermediate filaments has proved helpful to the pathologist in classifying poorly differentiated malignant neoplasms. In general, identification of keratin-type intermediate filaments has been associated with epithelial histodifferentiation, but several exceptions to this generalization have been reported in the literature. A recent report identified false-positive immunostaining for keratin in osteosarcomas of the jaws that was attributed to cross-reactivity induced by enzyme digestion of the tissue specimens before immunostaining. Because the jaws are unique in the skeletal system because of their relatively high incidence of intraosseous epithelial neoplasms, false-positive immunoreactions for keratin could complicate differentiating sarcomatoid epithelial neoplasms from poorly differentiated osteosarcomas. To evaluate this possible pitfall in our laboratory, eight osteosarcomas of the jaws were evaluated for keratin immunostaining with polyclonal and monoclonal antibodies on tissue sections that had been enzymatically treated with protease. No immunostaining was demonstrated in these tumors. Repudiation of the usefulness of antikeratin immunohistochemistry for intraosseous jaw tumors was not confirmed with the procedures used in our laboratory.

Production of monocyte chemoattractant protein-1 by malignant fibrous histiocytoma: relation to the origin of histiocyte-like cells

Human malignant fibrous histiocytoma (MFH) comprise both fibroblast-like cells and histiocyte-like cells. We previously showed that the latter are not neoplastic cells, but are infiltrating macrophages. Since migration of blood monocytes into the tumor might be a response to a locally elaborated monocyte chemoattractant, we designed experiments to determine if the fibroblast-like tumor cells produced a chemoattractant for human monocytes. Malignant fibrous histiocytoma from three patients was put into culture. Cells of all three lines had a spindle shape, and showed no reactivity with antibodies against macrophages (MAC387), HLA-DR (LN3), or leukocyte common antigen. Immunohistochemically, they stained with antibody against human monocyte chemoattractant protein-1 (MCP-1). Culture supernatants of the three cell lines had chemotactic activity for monocytes. This activity was due to MCP-1, since it was absorbed by an anti-MCP-1 column. The production of MCP-1 by MFH tumor lines was confirmed by immunoprecipitation of metabolically labeled MCP-1. These results suggest that the histiocyte-like cells are the infiltrated macrophages that originate from blood monocytes attracted by tumor-derived MCP-1.

An immunohistochemical study of spontaneous histiocytic tumours in the rat

Immunocytochemistry was used to examine 18 cases of rat fibrous histiocytic tumours (11 malignant; seven benign). The diagnosis was made by light microscopic criteria and all cases were categorized as pleomorphic-storiform. A selection of polyclonal antibodies to histiocytic, muscle, neural and mesenchymal antigens was used. Fifteen tumours were positive with alpha 1-antitrypsin, four with alpha 1-chymotrypsin, ten with muramidase, five with desmin, 15 with neuron-specific enolase, 14 with S100, one with glial fibrillary acid protein and 12 with vimentin. Many tumours expressed several antigens, highlighting the confusion which has arisen with regard to the histiogenesis of fibrous histiocytic tumours in man, and supporting the concept of differentiation from a primitive mesenchymal common precursor able to differentiate in several directions.

Immunohistochemistry of markers of histiomonocytic cells in malignant fibrous histiocytomas. A monoclonal antibody study

Nine cases of malignant fibrous histiocytomas (MFH) were examined immunohistochemically in frozen sections with six different monoclonal antibodies to histiomonocytic and related cells (EBM11, HAM-56, KB90, antibodies to dendritic reticulum cells, HLADR and LCA). Ten other soft tissue sarcomas, two desmoid tumors, twelve carcinomas, three seminomas and four lymphomas were studied for comparison. All cases of MFH showed positivity for histiomonocytic cell antigens. In six cases, the positive cells could be clearly interpreted to be infiltrating non-neoplastic cells. However, immunoreactivity for multiple histiocytic markers (EBM11, HAM-56, KB90, HLADR) was seen in tumor cells in three cases of MFH. In one of these cases, the positivity could be verified with KP1, an antibody to histiomonocytic cells applied in formalin fixed and paraffin embedded tissue. None of the tumors was positive with the antibody to dendritic reticulum cells or LCA. In the series of non-histiocytic tumors, no cases showed widespread positivity for multiple histiocytic markers. Our results suggest that in relation to true histiomonocytic differentiation MFH might be a heterogeneous group of tumors. The widespread immunoreactivity for multiple histiocytic markers in some cases may indicate a true histiomonocytic differentiation in some MFHs.

Distribution of actin isoforms in sarcomas: an immunohistochemical study

The actin immunophenotype of eight benign mesenchymal tumors, 14 nonsarcomatoid tumors, and 46 sarcomatoid tumors was studied, using monoclonal antibodies (MoAb) specific for alpha-smooth muscle actin (clone 1A4), alpha- and gamma-smooth muscle actin (designated CGA7), and muscle actin (designated HHF35) on frozen sections. Tumor cells of nonsarcomatoid tissues were not reactive, but all leiomyomas and five of the seven leiomyosarcomas reacted with the three MoAbs. One leiomyosarcoma was immunoreactive for the MoAb 1A4 only. One of the six malignant schwannomas showed staining for muscle actin (HHF35). The 22 malignant fibrous histocytomas (MFH) expressed these actin isoforms in various degrees. One case immunoreacted with all three MoAbs, three reacted with 1A4 only, seven reacted with CGA7 and HHF35, and two reacted with HHF35 only. Nine MFHs were not immunoreactive for any of the MoAbs specific for (smooth) muscle and actin. In addition, the expression of desmin and collagen type IV was investigated for the group of leiomyosarcomas and MFHs. Desmin was found in five leiomyosarcomas and in two MFHs. Collagen type IV was seen in all leiomyosarcomas, and was seen weakly in a few small areas in four MFHs. When we take into account the expression of all markers tested [( smooth] muscle actin, desmin, and collagen type IV), then six of the 22 MFHs were unreactive for all these markers. Five of these six tumors were located intramuscularly, whereas only half of the total number of MFH cases had an intramuscular location. The fact that 15 of 22 MFHs displayed one or more markers linked with (smooth) muscle differentiation suggests that some of the MFHs may be classified as poorly differentiated leiomyosarcomas, and that MFH is not a unique entity.

Myxoid malignant fibrous histiocytoma of the bladder

Although the most common soft tissue sarcoma of adulthood, malignant fibrous histiocytoma (MFH) is an extremely rare tumor of the urinary bladder. Only three well-documented cases have been reported in the world literature. The patient presented in this report represents the first case of the myxoid variant to develop in the urinary bladder. Whereas all previous patients with MFH of the bladder had intermittent hematuria, this patient's chief complaint was bladder outlet obstruction due to extension of the tumor into the prostate. He was managed with radical cystoprostatectomy, postoperative radiation therapy to the tumor bed, and adjuvant chemotherapy using doxorubicin. The patient tolerated the therapy well and was disease-free at the 3-year follow-up visit. The histogenesis, clinical features, pathologic characteristics, and treatment considerations of this rare bladder tumor are discussed in detail.

Primary Laryngeal Malignant Fibrous Histiocytoma: A Case Report

Malignant fibrous histiocytoma (MFH) of the upper respiratory tract is rare. We report a case of laryngeal MFH in a 78-year-old man. The patient died 8 months after the first surgical treatment. The clinicopathologic features are described, and the importance of electron microscopy and immunohisto-chemical techniques in the differential diagnosis with so-called « sarcomatoid carcinoma » is stressed. The tumor has an aggressive biological behavior and tends to recur and metastasize.

Immunohistochemistry of solid tumors. Brief review of selected problems

The immunohistochemical approach to tumor typing has dramatically improved our possibilities in the objective diagnosis of neoplasms. Use of optimal material and careful techniques will help to maintain good sensitivity, specificity, and reproducibility of immunohistochemistry. However, the complexity of antigen patterns in tumors, and lack of comprehensive knowledge about them requires caution in the interpretation of results, and may prohibit the simple use of diagnostic algorithms. Especially it is not certain whether the results obtained from typical representatives of various tumor entities will pertain to borderline cases and to undifferentiated variants of the same entities. Use of panels of antibodies rather than the use of single "diagnostic" tests will help to avoid these diagnostic pitfalls. However, all tumor types do not have immunohistochemically distinctive features. This emphasizes the need to use other techniques in such cases, and also suggests that some entities, such as malignant fibrous histiocytoma, are from the point of view of immunohistochemistry diagnoses only made by exclusion rather than being specifically diagnosable entities. All diagnostic immunohistochemistry has to be interpreted in the context of standard histological examination.

Experimental rhabdomyosarcoma with regions like malignant fibrous histiocytoma (MFH)--a true double phenotypic pattern?

In murine sarcomas induced by 20-methylcholanthrene, histological features of malignant fibrous histiocytoma (MFH) as well as rhabdomyosarcoma were found in the same tumour both at light microscopy and at ultrastructural level. The areas showing rhabdomyomatous differentiation expressed vimentin, desmin, muscle-specific alpha-actinin, and sometimes myoglobin, but in the MFH areas only vimentin was expressed. A series of allografts in athymic mice, using tumour areas of both histological types, showed in every case a mixed pattern of tumour growth, whether the transplanted tissue was of MFH or rhabdomyosarcomatous type. This suggests that the MFH areas in the original experimental sarcomas were modulated disguised rhabdomyosarcomas. The significance of MFH-like areas in non-related soft tissue sarcomas is also discussed.

Gliosarcoma: an immunohistochemical study

Gliosarcomas contain both neuro-ectodermal and mesenchymal elements. Its histogenesis has been much debated and endothelial and adventitial fibroblast origins have been suggested, as has a "histiocytic" origin following the demonstration of antiprotease activity. Eight gliosarcomas have been examined with a panel of ten monoclonal and polyclonal antibodies to investigate the origin of the sarcomatous element. Glial fibrillary acid protein expression showed a sharp distinction between gliomatous and sarcomatous tumour components. Contrary to some previous reports factor 8-related antigen and Ulex europeus agglutinin stained vascular luminal endothelium but no tumour cells. Vimentin and fibronectin expression was extensive and confined largely to sarcomatous areas. Desmin and neurofilament protein could not be demonstrated in any of the cases. Numerous cells, particularly in the sarcoma areas, expressed alpha-1-antitrypsin and -chymotrypsin. A proportion of these stained for the monocyte/macrophage marker MAC 387. Four cases focally exhibited a true storiform pattern and this and the immunohistochemical results suggest analogies with the fibrous histiocytomas. These tumours contain reactive histiocytes but are now thought to be derived from fibroblasts or from pluripotent mesenchymal cells in perivascular adventitia. This resembles the pattern exhibited in the sarcomatous component of gliosarcomas.

Osteoclasts are present in the giant cell variant of malignant fibrous histiocytoma

We assessed the osteoclast-like giant cells in a giant cell-rich variant of malignant fibrous histiocytoma (MFH) for characteristics which are specific for osteoclasts, including excavation of bone and binding of osteoclast-specific monoclonal antibodies. Excavations characteristic of osteoclastic activity were found when the bone slices were inspected in the scanning electron microscope after incubation. Two monoclonal antibodies which bind specifically to osteoclasts showed strong membrane reactivity. These results provide strong evidence for the osteoclastic nature of the giant cells in this variant of the MFH. Osteoblasts are known to control the function of the osteoclast, and since there is bone formation present in at least half of the giant cell-rich variant of MFH it may be that it is the cells with properties peculiar to osteoblasts within the tumour which are responsible for the recruitment of the osteoclasts.

Myxoid malignant fibrous histiocytoma with erythrophagocytosis

A tumor that formed multiple protuberant masses on the foot and leg of a 50-year-old white male had the light and electron microscopic features of a myxoid malignant fibrous histiocytoma. Ultrastructurally, the cells had some fibroblastic features. Extravasated erythrocytes were present throughout the tumor nodules and many had been phagocytosed by the tumor cells. Endothelial cell markers were negative.

Malignant fibrous histiocytoma of the anal canal. Report of a case and review of the literature

Malignant fibrous histiocytoma is a pleomorphic sarcoma that classically arises in the extremities and metastasizes to the lungs and regional lymph nodes. A review of the literature revealed only four previous cases of primary gastrointestinal malignant fibrous histiocytoma, all of which were treated by resection. This report describes a unique case arising in the anal sphincter that was treated by abdominoperineal resection and radiotherapy. The pathology of the condition, including immunocytochemical methods used to identify the tumor and its likely cell of origin, is discussed. The importance of long-term follow-up with repeated chest x-ray and local lymph-node examination is emphasized.

Malignant fibrous histiocytoma: similarities to the "fibrohistiocytoid cells" in chronic inflammation

Ultrastructural, enzyme histochemical and immunohistochemical studies were performed on tissue obtained from eight cases of malignant fibrous histiocytoma (MFH) and five cases of sacral decubitus ulcer. The MFH was composed of two major tumour cell types: fibroblast-like and histiocyte-like cells. Both cell types demonstrated abundant branching, fragmented rough endoplasmic reticulum (rER), many free ribosomes, occasional small mitochondria, an oval, elliptical or irregularly shaped nucleus with one or two prominent nucleoli and often a few dense bodies. However, pseudopodial projections, multivesicular bodies and phagosomes, common histiocyte organelles, were not seen. With little difference between cases or selection sites, the MFH cells reacted to acid phosphatase (AcP) and alpha-naphtyl butyrate esterase (ANBE) by enzyme histochemistry and with ferritin (Fer), alpha 1-antitrypsin (AT), alpha 1-antichymotrypsin (ACT), fibronectin (FN), HLA-DR, HLA-DP, Leu 10 and OKT 9 in immunohistochemical studies. MFH tumour cells did not immunostain with monocyte/macrophage markers (Leu M1, Leu M3, Mo 1, Mo 2 and Macrophage) although non-neoplastic histiocytes did react to these markers. In addition, granulation tissue, such as that found in sacral decubitus ulcers, was examined and the existence of a specific cell type called the "fibrohistiocytoid (FH) cell" was documented. The FH cell was short, spindle shaped and elliptical. Ultrastructurally, it had fragmented rER distributed in a branching pattern, dispersed free ribosomes, small mitochondria and a few dense bodies, but lacked diverse fused lysosomes and distinct pseudopodial cytoplasmic extensions. The FH cells reacted with AcP, alkaline phosphatase and ANBE but not with peroxidase using enzyme histochemistry and with Fer, AT, ACT, FN, HLA-DR, HLA-DP, Leu 10 and OKT 9 but not with monocyte/macrophage markers, C3d receptor, C3bi receptor in immunohistochemical studies. The FH cells had morphological, enzyme histochemical and immunohistochemical characteristics intermediate between fibroblasts and histiocytes. Similarities between MFH cells and the FH cells seen in chronic inflammation are discussed.

Histiocytic differentiation in benign and malignant bone tumors

In this study fresh frozen tissue samples of benign osseous tumors (five non-osteogenic fibromas, one fibrous dysplasia, one chondromyxoidfibroma), tumors of uncertain biological behaviour (eight cases of histiocytosis X, two giant-cell tumors), and of malignant intraosseous tumors (two malignant fibrous histiocytomas, two malignant histiocytosis, four osteosarcomas, one chondrosarcoma and two Ewing sarcomas) were studied with a panel of monoclonal antibodies reactive with monocyte/macrophages and various types of dendritic cells. In addition, tumors were further defined with a broad spectrum of antibodies against filamentous proteins and lymphocyte differentiation antigens. The specimens were stained with a triple-layer immunoalkaline phosphatase protocol. Tumors stained with these antibodies could be roughly divided into two groups. The first group comprised tumors with one predominant cell population reactive with one particular monoclonal antibody. In this group, cases of histiocytosis X were found to be consistently labelled with CD-1 antibodies. The giant-cell tumors showed a very homogeneous staining with certain monocyte/macrophage antibodies (Ki-M8). Nevertheless, even in these tumors, heterogeneity was demonstrated by the occurrence of cells with monocytic differentiation in histiocytosis X and conversely by the occurrence of cells with differentiation antigens of the dendritic cell system in giant-cell tumors. An exception has to be made for the two cases of malignant histiocytosis examined. These tumors were selectively labelled with antibodies against monocyte/macrophages (Ki-M8, IOM-1). The second group comprised tumors showing a high degree of heterogeneity demonstrated by the varying amounts of tumor cells reacting with the applied markers of the monocyte/macrophage and dendritic cell systems. In most cases it was difficult to ascribe labelled cells to the tumor cell population as opposed to an "innocent bystander" inflammatory cell population. This distinction was especially difficult in malignant fibrous histiocytomas underlining the current concept that these tumors are of primitive mesenchymal rather than true histiocytic origin.

Cellular heterogeneity. Explanation for changing of tumor phenotype and biologic behavior in soft tissue sarcomas

Many human soft tissue sarcomas are known to show variable structures in a given tumor and to be able of changing the histological feature during the course of the disease. These facts prompted an experimental study in order to ascertain if by use of long-term cultures of an established rat fibrosarcoma cell line (RFS) in respective inoculation tumors a histological picture different from the original fibrosarcoma could be produced. It was found that inoculation tumors generated by later subcultures partly corresponded to tumors with features of malignant histiocytomas and malignant fibrous histiocytomas. In a further experiment we attempted to initiate metastatic dissemination of a primarily non-metastasizing xenotransplanted RFS sarcoma in nude mice. By repeated diminution operations comparable to inadequate tumor surgery in human metastasis formation in lung parenchyme was attained. Taking into account cellular heterogeneity as basically responsible for the phenomena observed, different causal aspects concerning the experimental results are discussed. We deduce from our findings that the concept of histogenetic classification of soft tissue sarcomas should be replaced by an interpretation according to the actual differentiation. This also applies to malignant fibrous histiocytomas which are at least in part mesenchymal tumors and not descendants of mononuclear phagocytic cells and may originate by a dedifferentiation process of otherwise defined sarcoma types.

Immunostaining for alpha 1-antichymotrypsin and alpha 1-antitrypsin in gliomas

Antisera to alpha 1-antichymotrypsin, alpha 1-antitrypsin and lysozyme were reacted with 20 cases of glioblastoma multiforme, seven anaplastic astrocytomas, eight astrocytomas, six oligodendrogliomas, four ependymomas and the cerebral cortex from six normal autopsy brains. In addition, two pleomorphic xantho-astrocytomas and two heavily lipidized malignant gliomas were similarly examined. All astrocytic lesions were confirmed with anti-GFAP antisera. Thirty astrocytic tumours (77%), four oligodendrogliomas (67%) and three ependymomas (75%) reacted positively with anti-alpha 1-antichymotrypsin; 25 astrocytic tumours (64%), three oligodendrogliomas (50%) and three ependymomas (75%) showed positive staining for alpha 1-antitrypsin. The pattern of staining with either of these two markers did not correlate with tumour grading. None of the gliomas examined stained positively with anti-lysozyme. Non-neoplastic glial elements did not react with any of the three antisera. The results of this study suggest that staining for alpha 1-antichymotrypsin and alpha 1-antitrypsin is of little value in the differential diagnosis of neuroepithelial or mesenchymal lesions in the brain.

Immunohistochemical and ultrastructural studies of a primary aortic intimal sarcoma

An intimal sarcoma of the abdominal aorta in a 63-year-old woman is reported. The clinical symptoms consisted of chronic arterial hypertension, vomiting and epigastric pain. Treatment was operative, but the patient died 20 hours after surgery. The studies were performed on a surgical specimen and on autopsy material. The aortic tumour consisted of pleomorphic spindle-shaped and giant cells. In the vertebral metastases a storiform pattern of the tumour cells was found. No specific features characteristic for leiomyogenic, lipogenic or an endothelial nature of the tumour giant cells was disclosed in electron microscopy and the picture rather indicated their histiocytic character. Of the 18 cellular markers studied, the immunostainings for vimentin and alpha-1-antichymotrypsin were evidently positive. The tumour was classified as a pleomorphic intimal aortic sarcoma probably a malignant fibrous histiocytoma (MFH). The literature on 26 previously published aortal tumours is reviewed with emphasis on their topographical distribution and histological classification. In only 4 previous cases was the final diagnosis supported by electron microscopical or immunopathological findings. The role of marker studies in the classification of aortal tumours is discussed.

Malignant fibrous histiocytoma of the lung

Malignant fibrous histiocytoma (MFH) is among the most common soft tissue sarcomas of adult life, but rarely occurs elsewhere. We report an example of primary MFH of the lung and review 15 previously reported acceptable cases with current follow-up information. Histologically, the tumor in our case was pleomorphic with storiform and fascicular areas. Tumor cells showed positive immunostaining for alpha 1-antitrypsin, alpha 1-antichymotrypsin, and vimentin. Stains for desmin, cytokeratin, myoglobin, epithelial membrane antigen, S-100 protein, and lysozyme were negative. Electron microscopic study showed histiocyte-like, fibroblast-like, intermediate, and undifferentiated tumor cells. A variety of methods were used to treat these patients. Two patients survived for 5 or more years, two were alive and well at 8 and 12 months, respectively, two were alive with metastatic tumor at 3 and 18 months, respectively, and ten patients died of tumor, with an average survival of 1 year.

Does the pleomorphic xanthoastrocytoma exist? Problems in the application of immunological techniques to the classification of brain tumors

A case of a fibrous xanthomatous tumor of the meninges is reported. This is a rare tumor of childhood in which the characteristic pleomorphic histology contrasts with the good clinical prognosis. These tumors were reclassified as pleomorphic xanthoastrocytomas (PXA) due to their glial fibrillary acidic protein (GFAP) positivity. In the present tumor, GFAP was absent from nearly all cell bodies in most of the leptomeningeal regions of the tumor but could be detected with greater frequency at the cortical-leptomeningeal border zones and in the areas in which the tumor had infiltrated the cortex. All the tumor cells expressed vimentin and in, addition, most expressed alpha-1-antitrypsin, alpha-1-antichymotrypsin, tartrate-resistant acid phosphatase, common leukocyte antigen, and OKM1. This spectrum of marker staining corresponded not only to the pattern observed in two cutaneous fibrous histiocytomas and one malignant fibrous histiocytoma, but also to the results previously published in the literature with regard to fibrohistiocytic tumors. By contrast, this spectrum of monocytic-histiocytic marker staining was not seen in gliomas. We, therefore, regard the PXA as a mesenchymal tumor of the meninges, identical to benign fibrous histiocytomas elsewhere in the body. The possible reasons why this mesenchymal tumor can show GFAP positivity in the leptomeningeal border zone are discussed.

Diagnostic immunohistochemistry of canine round cell tumors

Sixty-five canine skin neoplasms studied using immunocytochemistry, included 22 histiocytomas, 18 amelanotic melanomas, 14 cutaneous lymphosarcomas, six mast cell tumors, and five transmissible venereal tumors. Formalin-fixed, paraffin-embedded sections were stained using the avidin-biotin-peroxidase complex (ABC) immunoperoxidase technique for reactivity with S-100 protein, kappa and lambda immunoglobulin light chains, alpha-1-antitrypsin, alpha-1-antichymotrypsin, leukocyte common antigen (LCA), neuron-specific enolase, keratin, cytokeratin, muramidase, and vimentin. Detection of S-100, kappa and lambda light chains, neuron-specific enolase, and vimentin were most useful for screening these neoplasms. None of the markers examined was consistent in staining histiocytomas. While reactivity of S-100 (ten cases) and neuron-specific enolase (ten cases) was detected in some amelanotic melanomas, lambda light chain immunoglobulin (eight cases) was relatively consistent in cutaneous lymphomas. Mast cell neoplasms reacted with avidin and, therefore, were positive, even on negative control sections. Vimentin reacted strongly on all amelanotic melanomas and transmissible venereal tumors examined. These antibodies are helpful adjuncts in the differential diagnosis of canine skin tumors.

Atypical fibroxanthoma of the skin: a clinicopathological and immunohistochemical study and a discussion of its histogenesis

The morphological and immunohistochemical characteristics of 37 atypical fibroxanthomas of the skin were examined. Twenty-four tumours were nodular ulcerative lesions on the head and face of patients with a median age of 75 years, whereas 13 tumours occurred on the trunk and limbs of patients with a median age of 48 years. Both pleomorphic polygonal and giant cells as well as the spindle cell component of the tumours stained for the histiocytic markers alpha 1-antichymotrypsin, alpha 1-antitrypsin, lysozyme and, less frequently, for ferritin. Leu M1 antigen and peanut agglutinin receptors were not demonstrable in tumour cells. This antigenic profile was contrasted with the findings in six cases of dermatofibroma which were largely not reactive with the antisera used. The immunohistochemical findings in atypical fibroxanthomas suggest that they represent a homogeneous group of tumours which are related to tissue histiocytes. These results are discussed in the context of the published findings in other so-called fibrohistiocytic tumours including dermatofibrosarcoma protuberans and malignant fibrous histiocytoma. The diagnoses in three cases coded as atypical fibroxanthomas were revised on the basis of their showing a different immunohistochemical profile.