The Rise and Fall of Malignant Fibrous Histiocytoma
Robert A. Erlandson
Memorial Sloan-Kettering Cancer Center
South Burlington, VT
The chronology of what was for many years the most common soft tissue tumor of older adults,
malignant fibrous histiocytoma (MFH), begins in the early 1960's in the Laboratory of Surgical Pathology
at the College of Physicians and Surgeons of Columbia University under the tutelage of the eminent
pathologist Dr. Arthur Purdy Stout. Margaret R. Murray, Ph.D., who had a major influence on Stout's
studies of the histogenesis of tumors , found that the cells composing cultured explants of soft
tissue neoplasms characterized by a storiform or cartwheel-like growth pattern and variable numbers of
pleomorphic and giant tumor cells initially exhibited ameboid movement and phagocytosis, thus resembling
histiocytes. Upon further growth, the cells became elongate (bipolar shape) similar to fibroblasts.
Based on these observations, Stout and his associates postulated that these pleomorphic soft tissue
tumors arose from histiocytes that are capable of fibroblastic transformation, the so-called "facultative
fibroblast" . The term malignant fibrous histiocytoma was coined to designate these pleomorphic
tumors presumably derived from histiocytes that are capable of fibroblastic transformation
previously designated malignant histiocytoma and fibroxanthosarcoma  were also included in the
umbrella designation malignant fibrous histiocytoma .
Verification, Histologic Classification, and Histogenesis of MFH (1970's &
During the 1970's and 1980's a number of large series of cases of MFH were published reaffirming
the concept of MFH as a pathologic entity
. Since neoplasms designated as MFH exhibit a wide range
of histological appearances, Enzinger and Weiss subdivided them into five subtypes: 1.
Storiform-pleomorphic; 2. myxoid (myxofibrosarcoma); 3. giant cell (malignant giant cell tumor of soft
parts}; 4. inflammatory (xanthosarcoma and malignant xanthogranuloma}; and 5. angiomatoid
most common and prototypical histologic subtype is a cellular tumor consisting of a variable mixture of
storiform and pleomorphic areas aptly designated storiform-pleomorphic MFH. This classic subtype consists
of plump spindly fibroblastic cells arranged in short fascicles in a storiform or cartwheel pattern
around slit-like blood vessels. Occasional plump histiocytic cells also are evident. In the pleomorphic
areas, the fibroblastic cells are plumper and greater numbers of histiocytes are seen. A characteristic
feature of the pleomorphic areas is the presence of numerous giant tumor cells with hyperchromatic
irregular nuclei and an abundant cytoplasm. Mitotic figures, normal and abnormal, also are prominent.
Nonneoplastic elements include xanthoma cells and chronic inflammatory cells. Delicate collagen fibers
surround individual cells. In the myxoid subtype at least half of the tumor should be myxoid. Highly
myxoid neoplasms that contain well-differentiated bipolar fibroblastic cells have been designated
. Approximately one forth of cases of MFH are myxoid . The last three
variants of MFH are uncommon and more controversial. The giant cell subtype is a multinodular neoplasm
consisting of a mixture of fibroblasts, histiocytes and osteoclast-type giant cells. Bands of collagen
fibers and areas of hemorrhage and necrosis are notable. This variant is also termed malignant giant
cell tumor of soft parts . The inflammatory (prominent xanthoma cells and secondary inflammatory
cells) and angiomatoid (histiocytes, blood-filled spaces, intense inflammation, and extensive necrosis)
subtypes probably are not variants of MFH and require further study. They will not be discussed in this
presentation. Malignant fibrous histiocytoma thus became the commonest type of soft tissue sarcoma in
elderly adults until the 1990's.
Ultrastructural studies of many cases of MFH, notably the common storiform-pleomorphic subtype,
were published in these two decades in order to identify the cell types composing the sarcomas and
establish their histogenesis
. The following cell types were identified:
spindly fibroblastic cells with a prominent rough endoplasmic reticulum (RER); histiocytic
(histiocyte-like) plump cells containing lysosomes, lipid droplets, hyaline globules (some cells), 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;
myofibroblasts with RER cisternae and peripheral arrays of actin myofilaments; and xanthomatous cells
that have numerous membrane bound lipid droplets. The most common cell types were fibroblastic,
histiocyte-like, intermediate, and undifferentiated. The myxoid variant (myxofibrosarcoma) consisted of
fibroblastic cells with dilated RER cisternae containing a flocculent substance similar to that of the
myxoid matrix. The stroma also contained variable numbers of collagen fibers
Histochemical and immunohistochemical studies demonstrated the presence of a number of lysosomal
enzymes primarily in the histiocytic cells, notably acid phosphatase , naphthyl thiol acetate
esterase , alpha-1-antitrypsin and antichymotrypsin
, lysozyme , and monocyte/macrophage
differentiation antigens . These findings were inconclusive since some of the investigators claimed
that the presence of lysosomal enzymes in the tumor cells indicated histiocytic origin
most of the reports (particularly in the late 1980's) stated that they do not express the characteristic
Three theories of histogenesis (cell of origin) emerged from the above studies. The overwhelming
majority of investigators favored origin from a primitive (undifferentiated) multipotential mesenchymal
cell that differentiates into both fibroblastic and histiocytic neoplastic cells
Only a minority of reports favored histiocytic
or fibroblastic  origin.
Concept of Malignant Fibrous Histiocytoma Challenged (1990's to Present)
Even before the last decade of the 20th century some distinguished pathologists
questioned the concept of MFH. In 1986, Enzinger stated that MFH has become a diagnosis of exclusion
, while Dehner in 1988 raised the question as to whether MFH is a morphologic pattern or a true
pathologic entity . Perhaps the most provocative report concerning the overdiagnosis of MFH was that
by Fletcher in 1992 . A critical review of 159 neoplasms diagnosed as pleomorphic sarcoma/MFH
revealed that only 13% could possibly be diagnosed as MFH. The majority of these tumors were pleomorphic
subtypes of other sarcomas, e.g., liposarcoma. Meister also raised the question as to whether MFH is a
histomorphologic pattern or a distinct tumor type . Fletcher, in his Soft Tissue Tumors chapter of a
Diagnostic Histopathology of Tumors book, stated that it is accepted that virtually none of the so-called
"fibrohistiocytic tumors" show true histiocytic differentiation and noted that the term
"fibrohistiocytic" is a misnomer . Fletcher also noted that in tumors designated pleomorphic MFH a
specific line of differentiation can be demonstrated in most cases. Precise classification of
"pleomorphic sarcoma/MFH" requires thorough sampling of the tumor and the judicious use of
immunohistochemistry and/or electron microscopy
More critical histochemical, immunohistochemical, and ultrastructural studies of cases of so-called
MFH, notably the storiform-pleomorphic classic subtype, also found that neoplastic histiocytes or
"facultative fibroblasts" are not present in these tumors
. McHugh and Miettinen reported that
the so-called histiocyte-specific marker KP1 (CD68) is found in a variety of soft tissue tumors as well
as melanomas and carcinomas . Iwasaki and associates suggested that MFH is a tumor of "facultative
histiocytes," or fibroblasts that show partial histiocytic differentiation, the opposite of the
"facultative fibroblast" . A critical evaluation of 130 cases of MFH, all of which were
ultrastructurally examined in our laboratory at Memorial Sloan-Kettering Cancer Center, found that the
classic storiform-pleomorphic subtype, and most likely the myxoid and giant cell variants are
fibrosarcomas variably consisting of fibroblasts with a well developed RER which often is dilated,
myofibroblasts with additional peripheral actin myofilaments, large rounded fibroblastic cells with an
abundant cytoplasm containing a prominent Golgi apparatus and variable numbers of primary and secondary
lysosomes, and undifferentiated mesenchymal cells cells with a scanty cytoplasm and few organelles .
In the myxoid tumors, the dilated cisternae of the fibroblasts contained a flocculent substance similar
to that found in the myxocollagenous stroma. In addition to various types of fibroblastic cells,
osteoclast-like multinucleate cells characterized the giant cell neoplasms. Excluding likely
nonmalignant osteoclasts, the giant fibroblastic tumor cells had primarily multisegmented nuclei with
clumped chromatin and large nucleoli. The abundant cytoplasm often contained accumulations of vimentin
filaments, which when prominent, appears rhabdoid by light microscopy and corresponds to the
hyaline/eosinophilia of the cytoplasm. The only true histiocytic cells identified in the tumors were
obviously nonneoplastic (reactive). The largest series of ultrastructurally studied cases of MFH was
published in 2000 by Suh, Ordonez, and Mackay from the M.D. Anderson Cancer Center in Houston, Texas
. They examined 157 cases representing the four main subtypes of MFH with immunohistochemical stains
performed on 77 neoplasms. Their findings were similar to ours. No true histiocytic differentiation was
evident and it was concluded that "malignant fibrous histiocytoma forms part of the histologic spectrum
of tumors of fibroblasts." However, the concept of MFH being a "pleomorphic fibrosarcoma" is still not
accepted by many surgical pathologists with an interest in soft tissue neoplasms, since fibrosarcomas are
regarded to consist of a relatively uniform population of spindle cells devoid of multinucleated or
pleomorphic giant cells – the classic definition
The Remarkable Differentiation Capabilities of the Fibroblast
In 1990, Sappini, Schurch and Gabbiani published an important paper concerning the differentiation
capabilities of fibroblastic cells, including the expression of cytoskeletal proteins as markers of these
phenotypic modulations . Schmitt-Graf and associates subsequently reported myofibroblastic
phenotypic heterogeneity as another example of fibroblastic cell plasticity . Benign and malignant
neoplasms composed primarily of myofibroblasts – myofibroblastomas and myofibrosarcomas – also were
. The current status of myofibroblasts in nonneoplastic conditions and
neoplasms is reviewed by Schurch et al. . Montgomery and Fisher recently reported cases of MFH in
which myofibroblastic differentiation of the neoplastic cells was prominent . They proposed the
designation "pleomorphic myofibrosarcoma" for these neoplasms.
In addition to smooth muscle and histiocytic differentiation, fibroblasts also are capable of
cytokeratin protein expression indicative of epithelial differentiation, notably in cases of MFH
In the cases of MFH expressing cytokeratin proteins, the number of immunoreactive cells varies
from only 1% to a high of 32%. We recently reported four cases of fibrosarcoma that morphologically
resembled plasmacytoma or carcinoma . Interestingly, cytokeratin markers were negative, two cases
expressed epithelial membrane antigen, and all the tumors were strongly positive for vimentin. In
addition to the classic ultrastructural features of fibroblasts, rudimentary cell junctions, lumen-like
structures, microvilli, and neurosecretory-type granules were variously seen in the four neoplasms.
Considering that "myofibroblast" is accepted terminology for fibroblasts exhibiting smooth muscle
features, in order to be consistent, we propose the designation "histiofibroblast" for the so-called
fibrohistiocytic cells, and "epithelialfibroblast" for the uncommon fibroblasts with cytokeratin
immunoreactivity and/or ultrastructural epithelial cell structures. The former designations "facultative
fibroblast," "facultative histiocyte," and "fibrohistioblast"  are archaic, confusing, and
inaccurate. Likewise, the commonly used term "fibrohistiocyte" is a misnomer since these cells are most
likely fibroblasts showing some histiocytic features .
and a Proposed New Classification for Tumors Formerly
Designated Malignant Fibrous Histiocytoma
It is intriguing why many pathologists do not accept the designation pleomorphic fibrosarcoma while
pleomorphic liposarcoma , leiomyosarcoma , and rhabdomyosarcoma  are recognized as distinct
histologic entities? It is noteworthy that Stout in his classic 1948 paper on fibrosarcoma classified
these tumors as congenital, fibroblastic, juvenile, myxoid, and pleomorphic variants `66,67}. Figure 9
of Hajdu's historic commentary on fibrosarcomas illustrates a "high grade pleomorphic fibrosarcoma with
pleomorphic fibroblasts in abundant collagenous matrix" . Ultrastructural examination of the large
pleomorphic tumor cells found in most cases of MFH have clearly shown that these cells are fibroblasts
. Hajdu also stated that "undifferentiated malignant fibrous Neoplasms" were
originally described by Stout in the 1950's.
On the basis of the above findings, we propose the following new classification for tumors that
were formerly designated "MFH", excluding Enzinger's controversial inflammatory and angiomatoid subtypes:
|Storiform-pleomorphic MFH|| Storiform-pleomorphic or pleomorphic |
Pleomorphic sarcoma, NOS
|Myxoid MFH || Pleomorphic Myxofibrosarcoma|
|Giant cell MFH || Giant cell fibrosarcoma with osteoclasts |
Malignant giant cell tumor of soft parts
When another entity such as pleomorphic liposarcoma , dedifferentiated liposarcoma (primarily
retroperitoneal tumors] , and pleomorhic malignant nerve sheath tumor  are ruled out, the
neoplasm should be designated pleomorphic fibrosarcoma. Rare cases that demonstrate no line of
differentiation by immunohistochemistry and electron microscopy should be classified as pleomorphic
sarcoma, not otherwise specified (NOS). The overwhelming majority of tumors designated the myxoid
subtype of MFH are pleomorphic myxofibrosarcomas
. The majority of the uncommon giant
cell variants of MFH are most likely giant cell fibrosarcomas with nonneoplastic osteoclasts
However, cases containing large numbers of histiocyte-like and xanthoma cells questionably show
fibroblastic differentiation and are more appropriately designated "malignant giant cell tumor of soft
parts" . Since the diagnostic term "malignant fibrous histiocytoma" is familiar to surgeons and
clinicians, when the new classification is used the term MFH should be placed in parenthesis after the
diagnosis, e.g., pleomorphic fibrosarcoma (MFH). Consider that hematologists and hematopathologists no
longer use the old term "malignant lymphoma, histiocytic type, diffuse" in the current non-Hodgkin's
It is interesting to speculate whether the MFH-like areas in other specific types of soft tissue
sarcoma exhibit fibroblastic differentiation. It has been reported that the most common pattern of
dedifferentiated areas of dedifferentiated liposarcomas consist of "high-grade pleomorphic MFH" or
"storiform fibroblastic MFH"
. As expected from the cellular complexity of "MFH", cases that
have had cytogenetic analysis show a wide range of abnormal karyotypes .
- Lattes R. Surgical Pathology at the College of Physicians and Surgeons of Columbia University. In: Rosai J, ed.Guiding the Surgeon's Hand. The History of American Surgical Pathology. Washington, DC: American Registry of Pathology, AFIP;1997:41-60.
- Ozzello L, Stout AP, Murray MR. Cultured characteristics of malignant histiocytomas and fibrous xanthomas. Cancer 1963;16:331-344.
- O'Brian JE, Stout AP. Malignant fibrous xanthomas. Cancer 1964;17:1446-1455.
- Kempson RL, Kyriakos M. Fibroxanthosaroma of soft tissues: a subtype of malignant fibrous histiocytoma. Cancer 1972;29:961-976.
- Stout AP, Lattes R. Tumors of soft tissue. In: Atlas of Tumor Pathology, 2nd Series, Fascicle 1. Washington, DC: AFIP, 1967:32-52.
- Weiss SW, Enzinger FM. Malignant fibrous histiocytoma: a analysis of 200 cases. Cancer 1978;41:2250-2266.
- Kearny MM, Soule E, Ivins JC. Malignant fibrous histiocytoma. A retrospective study of 167 cases. Cancer 1980;45:167-178.
- Enjoji M, Hashimoto H, Tsuneyoshi M, Iwasaki H. Malignant fibrous histiocytoma. A clinicopathologic study of 130 cases. Acta Pathol Jpn 1980;30:727-741.
- Weiss SW. Malignant fibrous histiocytoma: a reaffirmation. Am J Surg Path 1982;6:773-784.
- Enzinger F. Recent developments in the classification of soft tissue sarcomas. In: Management of Primary Bone and Soft Tissue Sarcomas. Chicago: Year Book of Medical Publishers, Inc., 1977.
- Enzinger FM, Weiss SW. Soft Tissue Tumors. St. Louis: CV Mosby; 1983:166-198.
- Leak LV, Caufield JB, Burke JF, et al. Electron microscopic studies on a human myxofibrosarcoma. Cancer Res 1967;27:261-285.
- Kindblom L-G, Merck C, Angervall L. The ultrastructure of myxofibrosarcoma. A study of 11 cases. Virchows Arch A 1979;381:121-139.
- Fukuda T, Tsuneyoshi M, Enjoji M. Malignant fibrous histiocytoma of soft parts: an ultrastructural quantitative study. Ultrastruct Pathol 1988;12:117-129.
- Lagace R. The ultrastructural spectrum of malignant fibrous histiocytoma. Ultrastruct Pathol 1987;11:153-159.
- Lagace R, Delage C, Seemayer TA. Myxoid variant of malignant fibrous histiocytoma. Ultrastructural observations. Cancer 1979;43:526-534.
- Tsuneyoshi M, Enjoji M, Shinohara N. Malignant fibrous histiocytoma. An electron microscopic study of 17 cases. Virchows Arch A 1981;392:135-145.
- Du Bouley CEH. Demonstration of alpha-1-antitrypsin and alpha-1-antichymotrypsin in fibrous histiocytomas using the immunoperoxidase technique. Am J Surg Pathol 1982;6:559-564.
- Soini Y, Miettinen M. Alpha-1-antitrypsin and lysozyme. Their limited significance in fibrohistiocytic tumors. Am J Clin Pathol 1989;91:515-521.
- Strauchen JA, Dimitriu-Bona A. Malignant fibrous histiocytoma: expression of monocyte/macrophage differentiation antigens detected with monoclonal antibodies. Am J Pathol 1986;124:303-309.
- Wood GS, Beckstead JH, Turner RR, Hendrickson MR, Kempson RL, Warnke RA. Malignant fibrous histiocytoma cells resemble fibroblasts. Am J Surg Pathol 1986;10:323-335.
- Lawson CW, Fisher C, Gatter KC. An immunohistochemical study of differentiation in malignant fibrous histiocytoma. Histopathology 1987;11:375-383.
- Brecker ME, Franklin WA. Absence of mononuclear phagocytic antigens in malignant fibrous histiocytoma. Am J Clin Pathol 1986;86:344-348.
- Taxy JB, Battifora H. Malignant fibrous histiocytoma. An electron microscopic study. Cancer 1977;40:254-267.
- Alguacil-Garcia A, Unni KK, Goellner JR. Malignant fibrous histiocytoma. An ultrastructural study of six cases. Am J Clin Pathol 1978;69:121-129.
- Fu YS, Gabbiani G, Kaye GI, Lattes R. Malignant soft tissue tumors of probable histiocytic origin (malignant fibrous histiocytomas): general considerations and electron microscopic and tissue culture studies. Cancer 1975;35:176-198.
- Roholl PJM, Kleijne J, van Basten CDH, van der Putte SCJ, van Unnik JAM. A study to analyze the origin of tumor cells in malignant fibrous histiocytoma. A multiparametric characterization. Cancer 1985;56:2809-2815.
- Enzinger FM. Malignant fibrous histiocytoma 20 years after Stout. Am J Surg Pathol 1986;(suppl) 10:43-53.
- Genberg M, Mark J, Hakelius L, Ericsson J, Nister M. Origin and relation between different cell types in malignant fibrous histiocytoma. Am J Surg Pathol 1989;135:1185-1196.
- Kauffman SL, Stout AP. Histiocytic tumors (fibrous xanthoma and histiocytoma) in children. Cancer 1961;14:469-482.
- Hoffman MA, Dickersin GR. Malignant fibrous histiocytoma. An ultrastructural study of 11 cases. Hum Pathol 1983;14:913-922.
- Dehner LP. Malignant fibrous histiocytoma. Non specific morphologic pattern, specific pathologic entity, or both? Arch Pathol Lab Med 1988;112:236-237.
- Fletcher CDM. Pleomorphic malignant fibrous histiocytoma: fact or fiction? A critical reappraisal based on 159 tumors diagnosed as pleomorphic sarcoma. Am J Surg Pathol 1992;16:213-228.
- Meister P. Malignant fibrous histiocytoma: histomorphological pattern or tumor type. Pathol Res Pract 1996;192:877-881.
- Fletcher CDM. Soft tissue tumors. In: CDM Fletcher, ed. Diagnostic Histopathology of Tumors. New York: Churchill Livingstone; 1995:1066-1072.
- Erlandson RA, Woodruff, JM. Role of electron microscopy in the evaluation of soft tissue neoplasms, with emphasis on spindle cell and pleomorphic tumors. Hum Pathol 1998;29:1372-1381.
- Takeya M, Yamashiro S, Yoshimara T, et al. Immunophenotype and immunoelectron microscopy characterization of major constituent cells in malignant fibrous histiocytoma using cell lines and their transplanted tumors in immunodeficient mice. Lab Invest 1995;72:679-688.
- Iwasaki H, Isayama T, Ohjimi Y, et al. Malignant fibrous histiocytoma. A tumor of facultative histiocytes showing mesenchymal differentiation in cultured cell lines. Cancer 1992;69:437-447.
- Erlandson RA. Diagnostic Transmission Electron Microscopy of Tumors: with clinicopathological, immunohistochemical, and cytogenetic correlations. New York: Raven; 1994:368-373.
- Hatano H, Tokonuga T, Ogose A,et al. Origin of the histiocytic cells and mujltinucleated giant cells in malignant fibrous histiocytoma: neoplastic or reactive? Pathol Int 1999;49:14-22.
- McHugh M, Miettinen M. KP1 (CD68): its limited specificity for histiocytic tumors. Appl Immunohistochem 1994;21:186-190.
- Suh CH, Ordonez NG, Mackay B. Malignant fibrous histiocytoma: an ultrastructural perspective. Ultrastruct Pathol 2000;24:243-250.
- Antonescu CR, Erlandson RA, Huvos AG. Primary fibrosarcoma and malignant fibrous histiocytoma of bone – a comparative ultrastructural study: evidence of a spectrum of fibroblastic differentiation. Ultrastruct Pathol 2000;24:83-91.
- Weiss LM. Soft tissues. In: Weidner N, Cote RJ, Suster S, Weiss LM, eds. Modern Surgical Patholoogy. Philadelphia: Saunders; 2003:1806-1816.
- Sappino AP, Schurch W, Gabbiani G. Differentiation repertoire of fibroblastic cells: expression of cytoskeletal proteins as markers of phenotypic modulation. Lab Invest 1990;63:144-161.
- Schmitt-Graf A, Desmouliere A, Gabbiani G. Heterogeneity of myofibroblast phenotypic features: an example of fibroblastic cell plasticity. Virchows Arch 1994;425:3-24.
- Herrera GA, Johnson WW, Lockard VG, et al. Soft tissue myofibroblastomas. Mod Pathol 1991;4:571-577.
- Mentzel T, Calonji E, Wedden C, et al. Myxofibrosarcoma. Clinicopathologic analysis of 75 cases with emphasis on the low-grade variant. Am J Surg Pathol 1996;20:391-405.
- Mentzel T, Fletcher CDM. The emerging role of myofibroblasts in soft tissue neoplasia. Am J Clin Pathol 1997;107:2-5.
- Montgomery E, Goldblum JR, Fisher C. Myofibrosarcoma. A clinicopathologic study. Am J Surg Pathol 2001;25:219-228.
- Eyden BP, Banerjee SS, Harris M, et al. A study of spindle cell sarcomas showing myofibroblastic differentiation. Ultrastruct Pathol 1991;15:367-378.
- Schurch W, Seemayer TA, Gabbiani G. The myofibroblast a quarter century after its discovery. Am J Surg Pathol 1998;22:141-147.
- Montgomery E, Fisher C. Myofibroblastic differentiation in malignant fibrous histiocytoma (pleomorphic myofibrosarcoma): a clinicopathological study. Histopathology 2001;38:499-509.
- Hirose T, Sano T, Abe J-I, et al. Malignant fibrous histiocytoma with epithelial differentiation? Ultrastruct Pathol 1988;12:529-536.
- Hirose T, Kudo E, Hasegawa T, Abe J, Hizawa K. Expression of intermediate filaments in malignant fibrous histiocytoma. Hum Pathol 1989;20:871-877.
- Miettinen M, Soini Y. Malignant fibrous histiocytoma: heterogeneous patterns of intermediate filament proteins by immunohistochemistry. Arch Pathol Lab Med 1989;113:13363-1366.
- Roholl PJM, Prinsen I, Rademakers PHM, et al. Two cell lines with epithelial cell-like characteristics established from malignant fibrous histiocytomas. Cancer 1991;68:1963-1972.
- Litzkey LA, Brooks JJ. Cytokeratin immunoreactivity in malignant fibrous histiocytoma and spindle cell tumors: comparison between frozen and paraffin-embedded tissues. Mod Pathol 1992;5:30-34.
- Rosenberg AE, O'Connell JK, Dickersin GR, Bhan AK. Expression of epithelial markers in malignant fibrous histiocytoma of the musculoskeletal system: an immunohistochemical and electron microscopic study. Hum Pathol 1993;24:284-293.
- Weiss SW, Brathauser BA, Morris PA. Postirradiation malignant fibrous histiocytoma expressing cytokeratin: implications for the immunodiagnosis of sarcomas. Am J Surg Pathol 1988;12:554-558.
- Antonescu CR, Erlandson RA. Fibrosarcoma mimicking plasmacytoma or carcinoma: an ultrastructural study of 4 cases. Ultrastruct Pathol 2001;25:31-37.
- Brooks JJ. The significance of multiphenotypic patterns and markers in human sarcomas. A new model of mesenchyme differentiation. Am J Surg Pathol 1986;125:113-123.
- Downes KA, Goldbllum JR, Montgomery EA, Fisher C. Pleomorphic liposarcoma: a clinicopathologic analysis of 19 cases. Mod Pathol 2001;14:179-184.
- Oda Y, Miyajma K, Kawaguchi K-I, et al. Pleomorphic leiomyosarcoma. Clinicopathologic and immunohistochemical study with special emphasis on its distinction from ordinary leiomyosarcoma and malignant fibrous histiocytoma. Am J Surg Pathol 2001;25:1030-1038.
- Gaffney EF, Dervan PA, Fletcher CDM. Pleomorphic rhabdomyosarcoma in adulthood: analysis of 11 cases with definition of diagnostic criteria. Am J Surg Pathol 1993;17:601-609.
- Stout AP. Fibrosarcoma: the malignant tumor of fibroblasts. Cancer 1948;1:30-63.
- Hajdu SI. Fibrosarcoma. A historic commentary. Cancer 1998;82:2081-2089.
- Coindre J_M, Mariani O, Chibon F, et al. Most malignant fibrous histiocytomas developed in the retroperitoneum are dedifferentiated liposarcomas: a review of 25 cases initially diagnosed as malignant fibrous histiocytoma. Mod Pathol 2003;16:256-262.
- Jabi M, Jeans, D, Dardick I. Ultrastructural heterogeneity in malignant fibrous histiocytoma of soft tissue. Ultrastruct Pathol 1987;11:583-592.
- Hirose T, Sano T, Hizawa K. Ultrastructural study of the myxoid area of malignant fibrous histiocytoma. Ultrastruct Pathol 1988;12:621-630.
- Henricks WH, Chu YC, Goldblum JR, Weiss SW. Dedifferentiated liposarcoma. A clinicopathologic analysis of 155 cases with a proposed expanded definition of dedifferentiation. Am J Surg Pathol 1997;21:271-281.
- Mc Cormick D, Mentzel T, Beham A, Fletcher CDM. Dedifferentiated liposarcoma. Clinicopathologic analysis of 32 cases suggesting a better prognosis subgroup among pleomorphic sarcomas. Am J Surg Pathol 1994;18:1213-1223.