Fibrosarcoma: a review and update.

Adult fibrosarcoma, defined by the World Health Organization as a 'malignant neoplasm composed of fibroblasts with variable collagen production and, in classical cases, a "herringbone" architecture', is a very rare soft tissue sarcoma. Once considered the most common adult sarcoma, the incidence of adult fibrosarcoma has declined dramatically over the past several decades. This is due to (i) evolution in the classification of soft tissue tumours (ii) recognition of clinically, morphologically and genetically distinctive subtypes of fibrosarcoma and (iii) increased understanding of the many other mesenchymal and non-mesenchymal tumours that may mimic fibrosarcoma. This review article will summarize the current state of our knowledge about strictly defined adult fibrosarcoma and discuss important entities in its differential diagnosis, including various fibrosarcoma variants, monophasic synovial sarcoma and other potential mesenchymal and non-mesenchymal mimics.

The contribution of electron microscopy to the characterization of soft tissue fibrosarcomas.

In recent years, with the application of immunohistochemical and cytogenetic methods, numerous lesions formerly diagnosed as fibrosarcoma were reclassified as other malignant soft tissue tumors, and therefore conventional fibrosarcoma has largely become a diagnosis of exclusion. On the other hand, several new entities belonging to the group of fibrosarcomas have been characterized, including low-grade fibromyxoid sarcoma / hyalinizing spindle cell tumor with giant rosettes, sclerosing epithelioid fibrosarcoma, acral myxoinflammatory fibroblastic sarcoma, and the epithelioid variant of myxofibrosarcoma. Electron microscopy has contributed to the identification of the fibroblastic phenotype in these fibrosarcoma variants and still retains a central role in the differential diagnosis of these soft tissue sarcomas, thus helping to render specific diagnoses and to broaden the spectrum of fibrosarcoma variants.

Low-grade fibromyxoid sarcoma: a clinicopathologic study of 18 cases, including histopathologic relationship with sclerosing epithelioid fibrosarcoma in a subset of cases.

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon tumor with diverse histopathologic features. It has been found to be histopathologically and genetically related to hyalinizing spindle cell tumor with giant rosettes. Lately, sclerosing epithelioid fibrosarcoma (SEF) has been identified as another rare variant of fibrosarcoma. Very few studies have addressed the aspect of its histopathologic relationship with LGFMS. The present study was conducted to critically analyze the clinicopathologic features of a series of LGFMS cases, including identification of cases with histopathologic similarity with SEF. During a 7-year period, 18 LGFMS cases were diagnosed in 9 male and 9 female patients, had ages ranging from 10 to 69 years (median, 32.5 years), and were most commonly identified in the lower extremities (8 cases, or 44.4%). Most cases (16, 88.8%) showed "classic" features of LGFMS with mild (13 cases, or 72.2%) to moderate atypia (5 cases) and nil mitosis (12 cases, or 66.6 %). Variable features included whorling tumor growth pattern, small rosettes, perivascular hyalinization, and amianthoid-like collagen, along with epithelioid differentiation and nuclear pseudoinclusions within tumor cells. Four cases (22.2%) with large collagenous rosettes were diagnosed as hyalinizing spindle cell tumor with giant rosettes. Distinct SEF-like areas were observed in 6 cases (33.3%). On immunohistochemistry, consistent vimentin positively reinforced fibroblastic lineage of the tumor. Therapeutically, all 4 of 7 cases with available follow-up details, which underwent wide excisions, have been free of disease at 5 to 61 months. Eight excisions with unclear margins included 3 cases free of disease (24, 36, and 52 months) and 1 case with recurrence and metastasis. Two cases of marginal excision had tumor recurrences, including 1 case that recurred after 10 years. Low-grade fibromyxoid sarcoma is an uncommon sarcoma with diverse histopathologic features. Histopathologic relationship exists between LGFMS and SEF in a few cases. An LGFMS is optimally managed with surgical wide excision and follow-up.

Detection of GNAS mutations in intramuscular / cellular myxomas as diagnostic tool in the classification of myxoid soft tissue tumors.

BACKGROUND: Intramuscular / cellular myxomas and low-grade myxofibrosarcomas are two different tumor entities with a significant histological overlap, especially if dealing with small biopsies. Despite the morphological similarities, they differ considerably in their biological behaviour. Intramuscular / cellular myxoma rarely shows signs of recurrence and never metastasizes, in contrast to myxofibrosarcoma that tends to recur more aggressively and to metastasize haematologically. Therefore, it is of great importance to distinguish these lesions - evaluation of GNAS mutation status could be of tremendous help. METHODS: We reviewed 13 cases with intramuscular / cellular myxomas. The 13 cases included 5 men and 8 women, aged from 33 to 71 years (mean age 55.5 years). Immunohistochemistry was performed as well as next generation sequencing. Ten cases were located in the lower extremities and three cases were located in the upper extremities. Two lesions were initially misdiagnosed as a low-grade myxofibrosarcoma. RESULTS: Performing next generation sequencing 12 out of 13 specimens showed a GNAS mutation. CONCLUSIONS: Our findings demonstrate that GNAS mutations are more common in intramuscular / cellular myxomas, than had been reported in literature in the past. Next generation sequencing for determining GNAS mutation status on small biopsies or diagnostically challenging cases facilitates the diagnosis of intramuscular / cellular myxoma and separates this tumor entity from its mimics.

Establishment and characterization of a novel myxofibrosarcoma cell line.

We established a novel human myxofibrosarcoma cell line NMFH-1 and analyzed it with spectral karyotyping and comparative genomic hybridization (CGH). NMFH-1 cells are composed of two different types of cells, small, spindle-shaped mononuclear cells and bizarre multinucleated giant cells, which were maintained in vitro over 200 passages. Xenografted tumor showed typical features of myxofibrosarcoma, which included bizarre multinucleated giant cells. Cytogenetic analyses revealed complex abnormalities, including a t(17;22)(q2?2;q13), which has been found in dermatofibrosarcoma protuberans. Subsequent reverse-transcription polymerase chain reaction revealed that the cell line did not have the COL1A1-PDGFB gene fusion. Significant gains of the 1q12 approximately q23 and 8q13 approximately qter regions and loss of the 9p21 approximately pter and 13q12 regions often found in MFH were observed by CGH analysis. We investigated the origin of multinucleated giant cells in xenografted tumor through DNA in situ hybridization. In this system, the human-specific Alu sequence and the mouse L1 sequence were used as specific cell markers of identity. In situ hybridization revealed neoplastic proliferation of the multinucleated giant cells of human origin.

The Evolution of Pediatric Soft Tissue Sarcoma Classification in the Last 50 Years.

This review discusses the history of the classification of soft tissue sarcomas in children and adolescents, the current transition toward integration of morphology and molecular genetics as new entities emerge, and future perspectives.

Proliferative fibroblastic lesions. From hyperplasia to neoplasia.

It is rare to find a pathologist whose ideas and beliefs are so sound and pervasive as to influence our thinking decades after his writing. Yet such was the case with Dr. Stout, to whom we owe our basic classification of fibroblastic tumors, our concept of fibromatosis, and our diagnostic approach to fibrosarcomas. We need to continue the progress Dr. Stout made in these areas and to search for biochemical and molecular differences in these tumors with the hope that this knowledge will lead to new avenues for therapy.

Sclerosing epithelioid fibrosarcoma: a cytogenetic, immunohistochemical, and ultrastructural study of an unusual histological variant.

A case of sclerosing epithelioid fibrosarcoma was studied. The tumor cells expressed vimentin, focally epithelial membrane antigen and CD34, contained cisternae of rough endoplasmic reticulum, large Golgi apparatus, many pinocytotic vesicles, and were devoid of basal lamina. Their composite karyotype was 45,Y,t(X;6)(q13;q15), t(6;13)(p11.2;q13),-22¿2/46,Y,t(X;6)(q13;q15),add(13)(p12), add(22)(q13)¿3/44 approximately 46,der(X)t(X;6)(q13;q21),-Y, t(13;14)(q10;q10),-22,add(22)(q13)¿7/46,XY¿8.

Classification and grading of soft-tissue sarcomas.

This article provides an overview of the classification of soft-tissue sarcomas as influenced by modern histopathologic techniques. The overview is followed by a practical grading system for these tumors based on a study of 282 eligible patients. The primary tumors of this trial were adequately treated. The quantitative data (mitotic count and size of the tumor) were based on the results of the statistical analysis.

Classification and grading of bone sarcomas.

Bone tumors generally are classified according to the cytologic features or products of the lesional cells. In most instances, the classification corresponds to a normal cell or tissue type indigenous to bone. This article focuses on sarcomas of bone and features a classification scheme similar to what has been described at the Mayo Clinic.

An improved system for quantifying AgNOR and PCNA in canine tumors.

BACKGROUND: Quantifying silver stained nucleolar organizer regions (AgNORs) and proliferation cell nuclear antigens (PCNA) are useful techniques to measure proliferative activity of tumor cells; however, the nonspecific deposition of stains and overlappings of AgNOR and PCNA counts between grades of tumors hamper their applications. MATERIALS AND METHODS: Fifty-two surgical specimens from dogs, including mast cell tumors, perianal gland tumors and hyperplasias, fibromas, fibrosarcomas, and normal tissues were studied. The 3 microns dewaxed sections of formalin-fixed tissues were stained to detect AgNORs by a modified inverted incubation technique in a newly developed silver staining device. Data were collected and analyzed using a high-resolution digital microscope camera and image analysis software. Sequential sections were also stained for PCNA using an immunohistochemical method. RESULTS: The improved system for quantifying AgNOR provided more accurate and non-overlapping mean AgNOR counts, which enable us to distinguish benign states from malignant changes. The mean AgNOR cut-off points that discriminated grade II or III mast cell tumors from grade I, perianal gland carcinomas from adenomas (or hyperplasia), fibrosarcomas from non-fibrosarcoma tissues, were 6.0, 14.1, 9.4, and 8.8 respectively. The mean AgNOR areas, relative AgNOR areas, and PCNA positive rates of some malignant and non-malignant tissues (benign tumor and normal tissues) were significantly different (P < 0.05). CONCLUSIONS: This improved system is a sensitive and rather precise method for quantifying the AgNOR and PCNA. It provides a valuable objective measurement for differentiating benign and malignant tumors.

Congenital-infantile fibrosarcoma: a clinicopathological study of five patients entered on the Prague children's tumor registry.

Five children with congenital-infantile fibrosarcoma are analyzed. The tumor was found at birth in four children: in one patient it was recognized at the age of 7 months. In three children the tumor affected the lower extremity. In one patient the inguinal region was the primary site, in another the abdominal wall. The morphology was that of a highly cellular spindle cell sarcoma with cells arranged in a fascicular pattern. Variations of this common pattern such as a cartwheel arrangement, and foci of small oval cells were observed. The immunohistochemistry revealed positivity of vimentin in four investigated tumors and muscle specific actin in three. Desmin, sarcomeric actin and myoglobin were all negative. There were scattered cells positive with KP1 (CD68), MAC 387, and in one case, with factor XIIIa antibodies which were considered to be reactive rather than tumor cells. The flow cytometry study showed DNA content in three tumors within diploid range; one tumor was hyperdiploid with the DNA index 1.2. Three children are disease-free from nine to 21 years after the diagnosis. One of them had the tumor preoperatively irradiated, and the subsequent histological examination revealed an almost complete tumor necrosis. In one patient there were six recurrences (treated by surgery only), and the child is well 25 months after the last recurrence. In one child the disease had an unusually aggressive course, and the patient died of widespread metastases to the lungs, lymph nodes and bones.

Fine-needle aspiration biopsy: dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) represents a spectrum of mesenchymal spindle cell tumors that typically involve both dermis and subcutis. Presented herein are six cases of DFSP, four of which were initially diagnosed by FNAB. The cytologic features useful in the identification of this lesion on Papanicolaou- and Diff-Quik-stained smears are discussed. Chief among these are the storiform stromal fragments, presence of entrapped adipose tissue and the recognition of fibrohistiocytic spindle cells. The potential pitfalls and the differential diagnostic possibilities of spindle-cell lesions, particularly those of fibrohistiocytic origin are discussed.

Fine needle aspiration cytology of low grade fibromyxoid sarcoma. Report of a case with histologic correlation.

BACKGROUND: Low grade fibromyxoid sarcoma, first described in 1987, is a rare sarcoma characterized by a bland and deceptively benign histologic appearance but with aggressive behavior. CASE: A 51-year-old female presented with a history of a recurrent and slowly growing mass in the left foot. Fine needle aspiration biopsy showed an abundant myxoid background with occasional thick bands of collagen. Tumor cells present in the myxoid background were spindle shaped, with focally mild or a light degree of nuclear enlargement, hyperchromasia and pleomorphism CONCLUSION: Low grade fibromyxoid sarcoma has particular cytologic features. Besides a careful cytologic evaluation of all the components, clinical and radiographic correlation is necessary to make the correct diagnosis.

Fibrosarcoma-like lipomatous neoplasm: a reappraisal of so-called spindle cell liposarcoma defining a unique lipomatous tumor unrelated to other liposarcomas.

The term "spindle cell liposarcoma" has been applied to liposarcomas (LPSs) composed predominantly or exclusively of spindled cells. These tumors have been considered variants of well-differentiated LPS (WDL), myxoid LPS, and spindle cell lipoma, suggesting that this is a heterogenous group of lesions. Using strict morphologic criteria and molecular and immunohistochemical analyses, we have identified a homogenous group of spindle cell lipomatous tumors, histologically and genetically distinct from other forms of LPS, which we have called "fibrosarcoma-like lipomatous neoplasm." Cases classified as "spindle cell LPS" or "low-grade LPS with spindle cell features" were reviewed. Final selection criteria included: (1) an exclusive low-grade spindle cell component resembling fibrosarcoma; (2) a mixture of bland fibroblastic cells resembling the preadipocyte and early-adipocyte stage of embryonic fat; and (3) molecular-genetic analysis that excluded other forms of lipomatous tumors. Of the initial 25 cases identified, comparative genomic hybridization (CGH) was uninformative in 2 cases; 5 were reclassified as WDL on the basis of molecular data (MDM2 amplification) and 6 as spindle cell lipoma (CGH profiles with a few gains and losses including a constant loss of chromosome 13 and frequent losses of chromosomes 16 and 6). The 12 remaining cases showed flat CGH profiles; of these cases, 11 were negative for DDIT3 gene rearrangements, and 1 result was uninterpretable. Patients ranged in age from 15 to 82 years (mean 50 y); male patients were affected slightly more often (7:5). Tumors arose in the deep (6) and superficial (3) soft tissue of the groin (4), buttock (3), thigh (2), flank (1), shoulder (1), and paratesticular tissue (1) and ranged in size from 2 to 20 cm (mean 7.5 cm). Clinical follow-up in 11 patients (9 mo to 20 y; mean 68 mo) showed no recurrences or metastases. As defined above, "fibrosarcoma-like lipomatous neoplasm" is a unique lipomatous tumor that should be distinguished from WDL/(low-grade) dedifferentiated LPS and myxoid LPS on combined histologic/molecular features because of its better prognosis.

[Fibrosarcoma in children and adolescents: different entities for the same name]. / Les « fibrosarcomes ¼ de l'enfant et de l'adolescent : un même nom pour différentes entités.

Fibrosarcomas (FS) are rare malignant tumors in pediatrics, classified in the heterogeneous non-rhabdomyosarcomas group of malignant mesenchymal tumors. Infantile FS are found typically in children less than 2 years of age, and include congenital FS usually occurring in infants in the first 3 months of life. Histological diagnosis can be difficult; and confirmed with detection by molecular biology of the ETV6-NTRK3 fusion protein. FS is most often a localized disease at diagnosis, with involvement of an extremity. The management of these patients must be multidisciplinary, to define the different phases of treatment and avoid mutilating surgery. Cellular or atypical mesoblastic nephroma (MN) is a subtype of malignant pediatric renal tumors, most often present in children of less than 3 months. Histopathological characteristics of the cellular MN are very close to the congenital FS due to a fusion transcript common to both diseases. Treatment schedule is defined by initial local stage of the disease. FS called "adult-type" found exceptionally in childhood occur most often after 10 years old. Adult FS differ from infantile FS in their clinical presentation because of a strong local aggressiveness and problematic appearance of metastasis in 50% of cases, sometimes late. These three diseases present therefore histological similarities. Both have a common name but different clinical presentation and outcome: infantile FS and adult FS. Two have different names and initial location but similar histology, chromosomal rearrangement, sensitivity to chemotherapy and outcome: the congenital FS and cellular mesoblatic nephroma. Authors present a review of the literature of these entities.