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Background
This rare soft tissue tumor was previously thought to be benign but fascinating tumor, probably related to nerves. However, recent reports have described tumors that may have a malignant behavior. Histopathologically, the pathologist is faced with an unusual tumor which must be distinguished from many other soft tissue tumors.
OUTLINE
EPIDEMIOLOGY CHARACTERIZATION INCIDENCE Rare AGE RANGE-MEDIAN 14-79 years Males favored
PATHOGENESIS CHARACTERIZATION CHROMOSOMAL ABNORMALITIES
Ossifying fibromyxoid tumor of soft parts. Cytogenetic findings.Nishio J, Iwasaki H, Ohjimi Y, Ishiguro M, Isayama T, Naito M, Okabayashi H, Kaneko Y, Kikuchi M.
Department of Pathology, School of Medicine, Fukuoka University, 814-0180, Fukuoka, Japan
Cancer Genet Cytogenet 2002 Mar;133(2):124-8 Abstract quote Ossifying fibromyxoid tumor (OFMT) of soft parts is a recently described, rare but morphologically distinctive soft tissue tumor. The histogenesis of this lesion remains uncertain, although several immunohistochemical and ultrastructural features suggest that it is an unusual neural tumor, possibly of Schwann cell origin.
We report here a case of a malignant variant of OFMT that
occurred in the foot of a
52-year-old man. The karyotype of a pulmonary metastasis
exhibited the following complex numeric and
structural aberrations:72 approximately 74,XXY,-5,+6,+del(8)(p21),del(9)(p22),+10,der(11)
t(3;11)(p21;p15),del(12) (q13),der(13)t(5;13)(q13;q34),
+18,+19,+20,-22 [cp10]. A kidney metastasis exhibited
the following karyotypic abnormalities: 46,XY,add(3)(p11),+der(3)t(3;?;11)
(3qter-->3p11::?::11q13-->11qter), -5,del(8)(p21),add(9)(q22),del(9)(p22),
der(11)t(3;11)(p21;p15),
del(12)(q13),
+der(13)t(5;13) (q13;q34),-22. To our knowledge, this is the first
reported case of OFMT in which clonal chromosomal aberrations have been shown.SCHWANN CELL ORIGIN Ossifying fibromyxoid tumor of soft parts: evidence supporting Schwann cell origin.
Donner LR.
Department of Pathology, Scott & White Memorial Hospital, Temple, TX 76508.
Hum Pathol 1992 Feb;23(2):200-2 Abstract quote Immunohistochemical and ultrastructural studies of an ossifying fibromyxoid tumor of soft parts have been performed. Immunoreactivity of neoplastic cells for S-100 protein and glial fibrillary acidic protein, lack of immunoreactivity for type II collagen, and presence of basal lamina indicate that the tumor is of Schwann cell and not cartilaginous origin.
LABORATORY/
RADIOLOGIC/
OTHER TESTSCHARACTERIZATION RADIOLOGIC Nasopharyngeal nonossifying variant of ossifying fibromyxoid tumor: CT and MR findings.
Thompson J, Castillo M, Reddick RL, Smith JK, Shockley W.
Department of Radiology, University of North Carolina School of Medicine, Chapel Hill 27599-7510, USA.
AJNR Am J Neuroradiol 1995 May;16(5):1132-4 Abstract quote The CT and MR findings of a nasopharyngeal nonossifying variant of an ossifying fibromyxoid tumor are presented. The findings are radiographically indistinguishable from more common malignant neoplasms encountered in this region.
The tumor was isointense with muscle on T1-weighted images. On proton density- and T2-weighted images, the mass was mostly isointense with gray matter but contained some areas of lower intensity that might reflect the fibrous tissue component. The tumor eroded through the floor of the middle cranial fossa.
Radiographic appearance of an ossifying fibromyxoid tumor of soft parts.Schaffler G, Raith J, Ranner G, Weybora W, Jeserschek R.
Department of Radiology, University of Graz, Austria.
Skeletal Radiol 1997 Oct;26(10):615-8 Abstract quote This case report describes an ossifying tumor in the left musculus erector spinae in a 32-year-old man. Radiologically it showed irregular lamellar bone formation in the periphery, demonstrating as juxtacortical and macroscopically sarcoma-like features. Histologic it was diagnosed as an ossifying fibromyxoid tumor of soft parts (OFTSP).
The CT features of this tumor have never previously been reported. This is the first time pulmonary metastases, malignant pleural effusion, and death of the patient directly related with an OFTSP have been described.
GROSS APPEARANCE/
CLINICAL VARIANTSCHARACTERIZATION GENERAL VARIANTS HEAD AND NECK
Ossifying fibromyxoid tumour (of soft parts) of the head and neck: a clinicopathological and immunohistochemical study of nine cases.Williams SB, Ellis GL, Meis JM, Heffner DK.
Department of Oral Pathology, Armed Forces Institute of Pathology, Washington, D.C.
J Laryngol Otol 1993 Jan;107(1):75-80 Abstract quote Ossifying fibromyxoid tumour (OFT) is a recently described, mesenchymal neoplasm originally defined as a borderline or low-grade malignant lesion. Prior reports of OFT characterize it as a slow growing lesion with a propensity to occur in both the upper and lower extremities. Most OFTs have occurred within the deep subcutis or skeletal muscle.
We report nine cases which arose in the head and neck region. Six of the nine tumours were classified as ossifying variants of OFT while two were non-ossifying variants that lacked a discernable shell of lamellar bone. One tumour was classified as a malignant OFT. Seven lesions occurred in a subcutaneous site while two lesions occurred intraorally beneath the gingival and palatal mucosa. The OFTs occurred in six men and three women (age range of 29-75 years).
The tumours had histological features compatible with previously described OFTs and consisted of lobulated nests of small, cytologically bland round cells (with the exception of one malignant OFT), with a myxoid to hyalinized stroma and were surrounded in part by dense fibrous connective tissue. Six cases had an incomplete rim of lamellar bone with occasional perpendicularly oriented spicules of bone. Five lesions were immunostained. S-100 protein, neuron specific enolase, and Leu-7 were found in three out of five tumours. Glial fibrillary acidic protein, smooth muscle actin (SMA), and muscle specific actin (MSA) were detected in two out of five lesions, although staining for SMA and MSA was weak in reactivity. Staining for vimentin was strongly positive in all five cases tested. The tumours were not reactive with antibodies directed against cytokeratin, epithelial membrane antigen or neurofilament protein.
Follow-up information, available in eight cases, revealed multiple local recurrences in the one tumour believed to be a malignant OFT. The histogenesis of these tumours is uncertain, although the preponderance of evidence suggests a Schwann cell origin.
PEDIATRIC
Ossifying fibromyxoid tumour of soft parts: report of four cases including one mediastinal and one infantile.Ekfors TO, Kulju T, Aaltonen M, Kallajoki M.
Department of Pathology, University of Turku, Finland.
APMIS 1998 Dec;106(12):1124-30 Abstract quote Four cases of ossifying fibromyxoid tumour of soft parts are described. One of them was in the mediastinum, a hitherto unreported location of this rare neoplasm. Another was removed from the subcutaneous tissue of the head of a two-year-old girl, the youngest patient so far described.
A peculiar feature of this tumour was haphazard spindle cell groups showing smooth muscle differentiation. One tumour was remarkably proliferative with 20 mitotic figures per 10 high power fields and 50% of cells positive for Ki-67 antigen. Immunohistochemical analysis revealed that all the tumours were diffusely positive for vimentin, and focally for S-100-protein. In addition to this the infantile tumour expressed focal alpha-smooth muscle actin, desmin and glial fibrillary acidic protein, while the mediastinal tumour expressed only alpha-smooth muscle actin and the highly proliferative one expressed none of these antigens.
Background cells, including histiocytes, lymphocytes and mast cells were numerous. DNA cytometry analysis using both static and flow methods showed that the mediastinal tumour contained two cell clones, while the others were diploid. The proliferative fraction of cells (S plus G2 phases) was prominent in the proliferative and infantile tumours.
Ossifying fibromyxoid tumor of soft parts in a child: a case report.Ijiri R, Tanaka Y, Misugi K, Sekido K, Nishi T.
Department of Pathology, Kanagawa Children's Medical Center, Yokohama, Japan.
J Pediatr Surg 1999 Aug;34(8):1294-6 Abstract quote Ossifying fibromyxoid tumor (OFMT) is a relatively rare tumor, most of which occur in adults with preferential localization in subcutis or muscles of the extremeties. Although Schwannian or cartilage origin has been suggested, histogenesis of this tumor still is unclear.
The authors present a 6-year-old girl with retroperitoneal OFMT showing paraspinal extension, who is alive and tumor free 9 years after excision.
The current case is the youngest reported patient showing unusual deep trunk site with surgically identified association with the spinal nerve. Both the clinical and histopathologic features strongly suggested Schwannian origin of this tumor.
SKIN
Department of Dermatology, University of Pennsylvania Medical School, Philadelphia, PA, USA.
Ossifying fibromyxoid tumor of soft parts (OFMT) is a rare mesenchymal neoplasm of intermediate malignant potential. The tumor most commonly occurs on the extremities with a male predominance.
We present an unusual case of OFMT occurring as a cystic lesion on the scalp of a female. A 67-year-old woman presented with a 6-year history of a well demarcated cystic scalp mass. Physical examination revealed a slightly movable, multilobular mass of the left parietal scalp which was subsequently excised.- Histological evaluation revealed an OFMT comprised of bland, small cells and a thick collagenous capsule containing an incomplete rim of lamellar bone. OFMT is an unusual tumor which can usually be considered as having an intermediate risk of malignancy. It generally occurs in the extremities with a male predominance. The clinical differential for a cystic mass on the scalp is broadened by this unusual case of an OFMT.
- Ossifying fibromyxoid tumor of the skin: a report of 2 cases with light microscopic, immunohistochemical, and electron microscopic characterization.
Saadat P, Pullarkat S, Kelly L, Vadmal M.
Department of Dermatology, University of Southern California-Keck School of Medicine, Los Angeles, California, USA.
J Am Acad Dermatol. 2005 Apr;52(4):644-7. Abstract quote
Ossifying fibromyxoid tumor is a rare fibro-osseous neoplasm occurring predominantly in the subcutaneous tissue and/or skeletal muscle of the extremities. The immunohistochemical and ultrastructural studies in reported cases favor neural or Schwannian origin.
To date, ossifying fibromyxoid tumor presenting as a primary skin tumor has not been described in the literature. Two cases of primary cutaneous ossifying fibromyxoid tumor with light microscopic, immunohistochemical, and ultrastructural characterization are presented.
Our observations also support neural differentiation of these tumors.
Ossifying fibromyxoid tumor of soft parts of the back.Nakayama F, Kuwahara T.
Department of Dermatology, Sakura Hospital, Toho University School of Medicine, Chiba, Japan.
J Cutan Pathol 1996 Aug;23(4):385-8 Abstract quote We report a first case of ossifying fibromyxoid tumor of soft parts of the back, a 10 x 9.5 x 6 cm well-circumscribed elevated subcutaneous tumor demarcated by an incomplete fibrous capsule with bone formation at its base. The tumor was composed of both myxomatous areas with spindle tumor cells and pseudoalveolar structures with oval tumor cells.
The tumor cells had evenly sized, oval nuclei without atypia and slightly eosinophilic cytoplasm with intracellular vacuoles. Immunohistochemical studies revealed positivity for vimentin and focal positivity for S-100 protein. Ultrastructural examination revealed a few filopodia-like processes, discontinuous basal lamina and a few primitive cell junctions. Based on these immunohistochemical and ultrastructural results, this tumor may be related to Schwann's cells. There has been no recurrence 5 years after wide local excision.
Ossifying fibromyxoid tumor of soft parts: a case report and review.Barrett TL, Skelton HG, Smith KJ, O'Grady TC, Proctor-Shipman L.
Department of Dermatology, Naval Medical Center, San Diego, CA, USA.
J Cutan Pathol 1996 Aug;23(4):378-80 Abstract quote Ossifying fibromyxoid tumor of soft parts is a recently described, rare but morphologically distinctive tumor of soft tissue, including subcutaneous soft tissue.
We report a case of ossifying fibromyxoid tumor of soft parts which occurred in the subcutaneous tissue of a 68-year-old male, and review the clinical, histologic, and immunohistologic features of this tumor. Ossifying fibromyxoid tumor of soft parts tends to occur in the subcutaneous tissue and have been reported from the head and neck, upper and lower extremities, and trunk. Immunohistologic studies have supported a neural origin.
While considered benign, local recurrence after excision is common and these tumors should be excised with clear margins to prevent recurrence.
SUBCUTANEOUS
Department of Surgical Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA.
Ossifying fibromyxoid tumor (OFMT) is an uncommon neoplasm occurring predominantly in the deep soft tissues of the trunk and proximal extremities. The lineage of this rare tumor to date is still uncertain.
We present a case of a subcutaneous OFMT that recurred 8 years after initial resection. The histological findings of the primary and recurrent lesions are compared along with the histologic features possibly associated with aggressiveness.
Dermatopathologists should consider OFMT in the differential diagnosis of subcutaneous neoplasms with a myxoid matrix.
HISTOLOGICAL TYPES CHARACTERIZATION GENERAL
Ossifying fibromyxoid tumor of soft parts: a report of 17 cases with emphasis on unusual histological features.Zamecnik M, Michal M, Simpson RH, Lamovec J, Hlavcak P, Kinkor Z, Mukensnabl P, Matejovsky Z, Betlach J.
Department of Pathology, Postgraduate Medical School, Bratislava, Slovak Republic.
Ann Diagn Pathol 1997 Dec;1(2):73-81 Abstract quote Ossifying fibromyxoid tumor of soft parts is an unusual benign neoplasm, with a tendency for local recurrence. Its typical microscopic appearance is that of a multinodular proliferation of round to spindle shaped cells separated by fibrous bands in which bone formation is often seen.
Herein, we present the clinicopathologic features of 17 examples of this tumor with particular emphasis on some unusual histopathologic features that may place pitfalls in the diagnosis of this tumor, including satellite micronodules, mucinous microcysts, absence of myxoid areas, crush artifact, multiple microcalcifications, epidermoid cysts, atypical chondroid differentiation with binucleate lacunar cells, pericytic growth pattern, and malignant change.
Awareness of these unusual morphologic features should lead to a search for areas displaying the more typical features of ossifying fibromyxoid tumor to arrive at a correct diagnosis.
Ossifying fibromyxoid tumor of soft parts. A clinicopathological analysis of 59 cases.
Enzinger FM, Weiss SW, Liang CY.
Armed Forces Institute of Pathology (AFIP), Department of Soft Tissue Pathology, Washington, D.C. 20306-6000.
Am J Surg Pathol 1989 Oct;13(10):817-27 Abstract quote We describe 59 cases of a microscopically unique neoplasm that has not been previously reported.
The tumor almost exclusively affected adults (range 14-79 years) and had a male predominance (38 men and 21 women). It presented in most cases as a small, painless, well-circumscribed mass (median, 4 cm) in subcutis or muscle. It occurred chiefly in the upper and lower extremities (40 cases) and less frequently in the trunk (11 cases) and the head and neck region (eight cases).
Microscopically, the tumor was partly lobulated and composed of small, round cells that had vesicular nuclei and indistinct cytoplasm. Typically, the cells were arranged in a cord- or nestlike pattern within a myxoid matrix that frequently showed transitions toward hyaline fibrosis and focal osteoid formation. In about two-thirds of the cases, the cells contained immunoreactive S-100 protein. An additional typical feature, seen in 48 (81%) of the 59 cases, was the presence of an incomplete shell of mature bone in the capsular region of the tumor.
Follow-up information, available in 41 cases, revealed that 11 patients (27%) experienced one or more recurrences. One patient with three recurrences developed a second tumor in the opposite thigh, presumably a metastasis. None of the patients died of the tumor, but three died of causes unrelated to the disease. Although the histogenesis is uncertain, cartilaginous or neural origin seem to be most likely.
Until this issue is resolved, we prefer the descriptive and less committal designation of "ossifying fibromyxoid tumor of soft parts."
Ossifying fibromyxoid tumor of soft parts. Additional observations of a distinctive soft tissue tumor.Miettinen M.
Department of Pathology, University of Helsinki, Finland.
Am J Clin Pathol 1991 Feb;95(2):142-9 Abstract quote The author studied four subcutaneous soft tissue tumors, similar to those recently described by Enzinger and associates (Am J Surg Pathol 1989;13:817) by the name "ossifying fibromyxoid tumor," by immunohistochemistry and electron microscopy to further understand the cellular nature of this lesion.
The four tumors were composed of uniform round cells often surrounded by a lacunar space. The tumors often contained a peripheral zone of metaplastic bone. The cellularity was high, but the mitotic rate was low, suggesting a benign or borderline nature of the lesion. Longer follow-up was available for three cases, showing recurrence-free survival times of 11, 8, and 3 years. Immunohistochemistry studies revealed that all tumors were strongly positive for S-100 protein and focally positive for Leu-7, whereas melanoma-specific marker HMB45 was negative. Vimentin was the main type of intermediate filament protein, and one case also contained scattered glial fibrillary acidic protein-positive cells. Epithelial markers (keratins, epithelial membrane antigen), desmin, and muscle actins were negative. Electron microscopic examination showed partial, sometimes reduplicated, basal lamina surrounding many cells. Complex cell processes were also present.
No myofilaments were found. The immunohistochemical and electron microscopic results may suggest that this tumor has Schwann's cell differentiation.
Ossifying fibromyxoid tumor of soft parts.Yoshida H, Minamizaki T, Yumoto T, Furuse K, Nakadera T.
Department of Pathology, Tottori University School of Medicine, Yonago, Japan.
Acta Pathol Jpn 1991 Jun;41(6):480-6 Abstract quote A histologically uncommon soft-tissue tumor of the extremities and neck of a 54-year-old male is reported. The solid, bony-hard tumors occurred at the inner region of the right thigh at 44 years of age with additional tumor formation at the posterior region of the same thigh, at the inner region of the right upper arm and at the neck during the following 10 years. All tumors were located in the deep muscle layer. The neck tumor directly invaded the fifth cervical vertebra and later the upper mediastinum.
Histologically, all three tumors of the extremities contained mixed lobular growths of round-to-fusiform cells with myxoid matrix and an extensive bone formation. The tumor cells showed a small round nucleus and eosinophilic cytoplasm lacking cytoplasmic glycogen. The myxoid matrix was stained significantly by alcian blue and colloidal iron and was digested completely by pretreatment with hyaluronidase. Another major component was mature bone trabeculae showing a dense meshwork throughout the entire tumor with active bone formation toward the periphery.
Positive immunostaining was obtained against antivimentin and S-100 protein antibodies.
We suggest that this uncommon tumor can be tentatively distinguished as an ossifying fibromyxoid tumor of soft parts, (an entity defined by Enzinger et al.) differing from other previously described soft-tissue tumors.
VARIANTS ATYPICAL AND MALIGNANT
Ossifying fibromyxoid tumor of soft parts: a clinicopathologic study of 70 cases with emphasis on atypical and malignant variants.Folpe AL, Weiss SW.
Am J Surg Pathol 2003 Apr;27(4):421-31 Abstract quote The ossifying fibromyxoid tumor of soft parts (OFMT) is an uncommon soft tissue neoplasm of uncertain lineage. Approximately 100 cases of OFMT have been reported. Although the majority behave in a benign fashion, very rare tumors with histologic and clinical evidence of malignancy have been reported. Criteria for malignancy in OFMT have not as yet been defined.
Seventy cases of OFMT were retrieved from our consultation archives and studied with respect to patient age and sex, tumor site and size, growth pattern, percentage of typical OFMT, cellularity and nuclear grade, mitotic figures (MF)/50 high power fields (HPF), atypical mitoses, necrosis, vascular invasion, and the presence of bone.
Immunohistochemistry for pancytokeratin, S-100 protein, smooth muscle actin, desmin, and collagen II was performed on a subset of cases. Follow-up information was obtained from the submitting pathologists and clinicians. The Fisher exact test was used for statistical analysis.
Patients (39 male, 31 female) ranged in age from 14 to 83 years (median 49 years). The tumors occurred primarily as subcutaneous or deeply seated masses in the trunk and proximal extremities and ranged from 1 to 14 cm (median 4.0 cm). The percentage of typical OFMT present in each case ranged from 0% to 100% (median 70%), and bone was present in 44 cases (63%). Mitotic activity ranged from 0 to 40 MF/50 HPF (median 2 MF/50 HPF), necrosis was present in 12 cases (17%), and vascular invasion was seen in 8 cases (11%). High cellularity or high nuclear grade was seen in 14 and 13 cases, respectively.
Immunohistochemical results were as follows: S-100 protein (33 of 55, 60%), pancytokeratin (5 of 48, 10%), smooth muscle actin (2 of 44, 5%), desmin (5 of 39, 13%), and collagen II (1 of 26, 4%).
Follow-up (51 cases, mean 54 months, median 36 months, range 5-151 months) showed local recurrences in nine patients and metastases in eight patients. Currently, 41 patients are disease free, 6 are alive with disease, 4 are dead of disease, and 1 died of other causes. The presence of high cellularity (p = 0.002), high nuclear grade (p = 0.001), or >2 MF/50 HPF (p = 0.004) were significantly associated with the development of metastatic disease and local recurrence. Infiltrative growth was also associated with increased risk of local recurrence (p = 0.03).
We conclude that the histologic spectrum of OFMT is broader than previously appreciated, as many clinically benign cases display moderate cellularity, nuclear enlargement, or have identifiable mitotic figures.
Our results strongly suggest that OFMT with 1) high nuclear grade or 2) high cellularity and mitotic activity of >2 MF/50 HPF should be regarded as sarcomas with significant potential for metastasis and untoward outcome ("malignant OFMT"). The remainder can be considered within the spectrum of OFMT, recognizing that even these lesions possess a risk, albeit very low, of metastasis.
Consequently, OFMT should be considered tumors of intermediate malignancy. Their line of differentiation remains unclear, although we suggest they may belong to the category of translocation-associated sarcomas, not all of which recapitulate a normal line of differentiation.
Atypical and malignant variants of ossifying fibromyxoid tumor. Clinicopathologic analysis of six cases.Kilpatrick SE, Ward WG, Mozes M, Miettinen M, Fukunaga M, Fletcher CD.
Department of Pathology, North Carolina Baptist Hospital, Bowman Gray School of Medicine, Winston-Salem, USA.
Am J Surg Pathol 1995 Sep;19(9):1039-46 Abstract quote Ossifying fibromyxoid tumor (OFMT) of soft parts is a recently defined fibro-osseous neoplasm, the biologic behavior of which is generally regarded as benign.
We report six variant cases of OFMT with histologic features of malignancy, two of which behaved aggressively. All these tumors arose in the extremities of adults (aged 36-76 years), and five of the six were subcutaneous. Four patients were men. Macroscopically, all the tumors were well circumscribed and somewhat lobulated. Cardinal morphologic features included lobules of round to spindled cells within a fibromyxoid matrix and randomly distributed, often centrally located osteoid within which were plump neoplastic cells.
In contrast to typical OFMT, a hypocellular, cytologically benign, lamellar bony shell was observed only focally; cellularity was increased (four cases), and mitotic activity was frequent, exceeding two mitotic figures per 10 high-power fields (three cases). One case associated with metastases was morphologically bland. Immunohistochemically, positivity for S-100 protein was observed in the primary tumors of three cases and in the pulmonary metastasis of a fourth. Desmin was positive in one case. Ultrastructural features in three cases were very similar to usual OFMT. Clinical follow-up revealed local recurrence in two cases; one patient has developed recurrent pulmonary metastases.
We believe these findings support the view that some atypical cases of OFMT exhibit morphologic patterns that might predict more aggressive behavior.
MYOFIBROBLASTIC DIFFERENTIATION
Ossifying subcutaneous tumor with myofibroblastic differentiation: a variant of ossifying fibromyxoid tumor of soft parts?Fukunaga M, Ushigome S, Ishikawa E.
Department of Pathology, Jikei University School of Medicine, Tokyo, Japan.
Pathol Int 1994 Sep;44(9):727-34 Abstract quote Immunohistochemical, ultrastructural, and flow cytometric studies were performed on an ossifying soft-tissue tumor, presumed to be a variant of ossifying fibromyxoid tumor of soft parts, which was located in the subcutis of the left buttock of a 76 year old Japanese woman.
Histologically, this was a benign-looking spindle, oval, or round cell lesion, having a fibrous capsule with a discontinuous rim of bone as seen in typical cases. However, this lesion was also characterized by a high degree of cellular proliferation in storiform and whorl arrangements, extensive ossification, osteoid and metaplastic bone formation and absence of myxoid features. In an immunohistochemical study using formalin-fixed, paraffin-embedded sections, many tumor cells expressed vimentin, S-100 protein, Leu-7, neuron specific enolase, and desmin. Ultrastructurally, this neoplasm consisted of fibroblast-like cells and myofibroblast-like cells. This tumor had an aneuploid DNA content.
No recurrence has been observed for 16 months. These results suggest that the neoplastic cells may show the phenotypic expressions of myofibroblast and also osteogenic differentiation.
SPECIAL STAINS/
IMMUNOPEROXIDASE/
OTHERCHARACTERIZATION SPECIAL STAINS IMMUNOPEROXIDASE
Ossifying fibromyxoid tumor of soft parts: a morphological and immunohistochemical study.Yang P, Hirose T, Hasegawa T, Gao Z, Hizawa K.
First Department of Pathology, School of Medicine, University of Tokushima.
Pathol Int 1994 Jun;44(6):448-53 Abstract quote A case is presented of ossifying fibromyxoid tumor of soft parts (OFMTSP) which occurred in the left cheek of a 59 year old Chinese woman.
Histologically, the tumor was located in the subcutis with a fibrous pseudocapsule that contained discontinuous rims of mature trabecular bone. The tumor cells were small, round to ovoid with a uniform, round nucleus and a pale or slightly eosinophilic cytoplasm. Most of the cells were arranged in a random manner, some in a vague lace-like pattern. Mitotic figures were extremely rare. The stroma appeared fibromyxoid with scattered foci of mucinous lakes.
Immunohistochemically, most of the neoplastic cells displayed immunoreactivities for S-100 protein, S-100 protein alpha, vimentin and alpha-smooth muscle actin; many tumor cells were positive for desmin. The tumor also showed stromal immunoreactivity for type IV collagen and was negative for cytokeratins, epithelial membrane antigen, glial fibrillary acidic protein, neurofilaments, muscle-specific actin, Leu-7, myelin-basic protein, osteocalcin and melanoma-specific antigen.
The immunophenotypes expressed by the present OFMTSP seem to reflect two lineages of neoplastic cell differentiation, that is of nerve sheath and of smooth muscle; at the present stage, it is premature to diagnose this lesion as either nerve sheath or smooth muscle tumor.
ELECTRON MICROSCOPY
Ossifying fibromyxoid tumour of soft parts: immunohistochemical and ultrastructural analysis.Schofield JB, Krausz T, Stamp GW, Fletcher CD, Fisher C, Azzopardi JG.
Department of Histopathology, Hammersmith Hospital, London, UK.
Histopathology 1993 Feb;22(2):101-12 Abstract quote Ossifying fibromyxoid tumour of soft parts is a recently described benign neoplasm which usually presents in soft tissue. The histogenesis or pattern of differentiation is a source of controversy. Thirteen cases are reported herein. All arose in adults, principally on the upper trunk or head and neck region. None recurred. All but one tumour showed a shell of lamellar bone, laid down by reactive osteoblasts, at the tumour-host interface.
The characteristic laciform, glomoid and fascicular patterns, usually in combination, necessitate differential diagnosis from chondroid, smooth muscle and neural tumours especially. Immunohistochemistry revealed positivity for S-100 protein in 10/12, desmin in 7/10 and smooth muscle actin in 4/8.
Ultrastructural examination of four cases revealed prominent intermediate filaments, without myofilamentous organization, and a discontinuous external lamina. Immunoelectronmicroscopy localized desmin positivity to the filamentous meshwork. Differentiation therefore appears to take the form of an incomplete neural and smooth muscle phenotype, without evidence of complete maturation.
DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES LOW-GRADE FIBROMYXOID SARCOMA
Low-grade fibromyxoid sarcoma: a report of eight cases with histologic, immunohistochemical, and ultrastructural study.Zamecnik M, Michal M.
Department of Pathology, Slovak Postgraduate Academy of Medicine, Derer's Hospital, Bratislava.
Ann Diagn Pathol 2000 Aug;4(4):207-17 Abstract quote We present eight cases of low-grade fibromyxoid sarcoma (LGFS) of soft tissues. The patients, six men and two women, ranged in age from 28 to 44 years (median, 39 years).
All tumors were subcutaneous. They were located in the lower extremity (three cases), inguinal/perineal region (two cases), trunk (one case), upper extremity (one case), and neck (one case). Grossly, the lesions were similar to those described in previous studies; fibrous and well circumscribed, with pseudocapsules, and without any necrosis or nodularity. In a single case of hemosiderin-rich tumor, rusty brown strips were seen on the cut surface. Histologically, the tumors were composed of alternating fibrous and myxoid areas with various cellularity and with swirling and whorled growth patterns. The cells were stellate or spindle shaped and displayed none to mild nuclear pleomorphism and hyperchromasia. Some hypercellular areas showed a fascicular or herring bone pattern similar to common fibrosarcomas. In addition to the known typical picture of LGFS, we also have seen some unusual features. The cells of myxoid areas were often arranged in rows, thus resembling ossifying fibromyxoid tumor or myxoid chondrosarcoma of soft tissues. In a single case, the tumor cells contained a large amount of hemosiderin and the cellular nests contained synovial metaplasia-like clefts. The intranuclear invaginations of cytoplasm represented another interesting finding that was present in all tumors in our series.
They seem to be constant or at least frequent features of LGFS, which may assist in the differential diagnosis. The immunohistochemical and ultrastructural findings were consistent with the fibroblastic nature of LGFS. Four cases also showed features of possible histiocytic modulation of the neoplastic fibroblasts.
OSSIFYING EPITHELIOID HEMANGIO-ENDOTHELIOMA
Ossifying epithelioid hemangioendothelioma.Kiryu H, Hashimoto H, Hori Y.
Department of Dermatology, Kitakyushu Municipal Medical Center, Japan.
J Cutan Pathol 1996 Dec;23(6):558-61 Abstract quote A case of small epithelioid hemangioendothelioma encapsulated by an egg-shaped bony shell composed of newly formed mature lamellar bone is presented. A nodule measuring 10 x 5 x 5 mm was excised from inside of the right cheek muscle of a 46-year-old man.
Histopathologically, the nodule consisted mainly of round-to-short spindled epithelioid cells with round nuclei and occasional cytoplasmic vacuoles associated with some foci of osseous metaplasia. Characteristically, egg shell-like lamellar bone enclosed this lesion showing well-circumscribed appearance. The main component cells were immunohistochemically stained positive for factor VIII-related antigen, CD 34, UEA-1, and vimentin, and proved to be vascular endothelial cells. The term ossifying epithelioid hemangioendothelioma is proposed for this unique lesion.
This type of epithelioid hemangioendothelioma has not been previously reported to our knowledge, and differentiation from ossifying fibromyxoid tumor of soft parts is considered to be important.
PARACHORDOMA
Parachordoma: a clinicopathologic and immunohistochemical study of four cases of an unusual soft tissue neoplasm.Fisher C, Miettinen M.
Department of Histopathology, Royal Marsden NHS Trust, London, UK.
Four soft tissue tumors correspondi
Ann Diagn Pathol 1997 Oct;1(1):3-10 Abstract quote Four soft tissue tumors corresponding with the previously reported parachordoma are described. Three of the patients were men, and one was a woman, and their ages ranged from 14 to 53 years (mean age, 29).
The tumors were located either superficially or within muscle, and, in one case, involved a tendon. Histologically, the tumors displayed whorls, nests, and pseudoglandular cords of uniform polygonal cells with eosinophilic, vacuolated cytoplasm, in a focally myxoid stroma. Transitions were seen between fascicles of ovoid-spindled cells, with scanty cytoplasm in a fibrous stroma, and, in one case, whorls of bland spindly cells were also present. Electron microscopy of one case showed cells with short interdigitating microvilli and ill-defined junctions. The principal cells in all cases were positive for S100 protein, Leu-7, keratin (CAM5.2), and epithelial membrane antigen (EMA). All tumors were negative with antibody AE1 and with antibodies to cytokeratins CK7 and CK19. No tumor displayed immunoreactivity for carcinoembryonic antigen (CEA), muscle specific actin (MSA), smooth muscle actin (SMA), desmin, glial fibrillary acid protein (GFAP), CD31, or CD34.
Parachordoma appears to be an entity with clinical and pathological differences from chordoma, which has a different cytokeratin profile, behaves in a more aggressive fashion, and can dedifferentiate. The differential diagnosis includes myxoid chondrosarcoma, myoepithelial cell tumor, ossifying fibromyxoid tumor, and chondroid lipoma.
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