Fibrosarcoma (fibroblastic sarcoma) is a malignant mesenchymal

tumour A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

derived from fibrous connective tissue and characterized by the presence of immature proliferating fibroblasts or undifferentiated

anaplastic Anaplasia (from grc, ἀνά ''ana'', "backward" + πλάσις ''plasis'', "formation") is a condition of cells with poor cellular differentiation, losing the morphological characteristics of mature cells and their orientation with respect to e ...

spindle cells in a

storiform pattern A woven or storiform pattern is a histopathologic architectural pattern. The name "storiform" originates from Latin ''storea'' (''woven''), as storiform tissue tends to resemble woven fabric on microscopy. Storiform fibrosis is a histologic sign ...

. Fibrosarcomas mainly arise in people between the ages of 25–79 It originates in fibrous tissues of the bone and invades long or flat bones such as the femur, tibia, and mandible. It also involves the periosteum and overlying muscle.

Presentation

Adult-type

Individuals presenting with fibrosarcoma are usually adults thirty to fifty-five years old, often presenting with pain. Among adults, fibrosarcomas develop equally in men and women.

Infantile-type

In infants, fibrosarcoma (often termed congenital infantile fibrosarcoma) is usually congenital. Infants presenting with this fibrosarcoma usually do so in the first two years of their life. Cytogenetically, congenital infantile fibrosarcoma is characterized by the majority of cases having a translocation between chromosomes 12 and 15 (notated as t(12;15)(p13;q25)) that results in formation of the fusion gene, ''ETV6-NTRK3'', plus individual cases exhibiting trisomy for chromosomes 8, 11, 17, or 20. The histology, association with the ''ETV6-NRTK3'' fusion gene as well as certain chromosome trisomies, and the distribution of markers for cell type (i.e.

cyclin D1 Cyclin D1 is a protein that in humans is encoded by the ''CCND1'' gene. Gene expression The CCND1 gene encodes the cyclin D1 protein. The human CCND1 gene is located on the long arm of chromosome 11 (band 11q13). It is 13,388 base pairs lon ...

and

Beta-catenin Catenin beta-1, also known as beta-catenin (β-catenin), is a protein that in humans is encoded by the ''CTNNB1'' gene. Beta-catenin is a dual function protein, involved in regulation and coordination of cell–cell adhesion and gene transcrip ...

) within this tumor are similar to those found in the cellular form of mesoblastic nephroma. Indeed, mesoblastic nephroma and congenital infantile sarcoma appear to be the same disease with the exception that mesoblastic lymphoma originates in the kidney whereas congenital infantile sarcoma originates in non-renal tissues.

Pathology

The tumor may present different degrees of differentiation: low grade (differentiated), intermediate malignancy and high malignancy (anaplastic). Depending on this differentiation, tumour cells may resemble mature fibroblasts (spindle-shaped), secreting

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whol ...

, with rare mitoses. These cells are arranged in short fascicles which split and merge, giving the appearance of "fish bone" known as a herringbone pattern. Poorly differentiated tumors consist in more atypical cells, pleomorphic, giant cells, multinucleated, numerous atypical mitoses and reduced collagen production. Presence of immature blood vessels (sarcomatous vessels lacking endothelial cells) favors the bloodstream metastasizing. There are many tumors in the differential diagnosis, including spindle cell

melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...

, spindle cell

squamous cell carcinoma Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...

, synovial sarcoma,

leiomyosarcoma Leiomyosarcoma is a malignant (cancerous) smooth muscle tumor. A benign tumor originating from the same tissue is termed leiomyoma. While leiomyosarcomas are not thought to arise from leiomyomas, some leiomyoma variants' classification is evolvi ...

, malignant peripheral nerve sheath tumor and biphenotypic sinonasal sarcoma.

Diagnosis

Ancillary testing for fibrosarcoma includes IHC, where

vimentin Vimentin is a structural protein that in humans is encoded by the ''VIM'' gene. Its name comes from the Latin ''vimentum'' which refers to an array of flexible rods. Vimentin is a type III intermediate filament (IF) protein that is expresse ...

is positive, cytokeratin and S100 are negative, and

actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...

is variable.

In animals

Dogs

Fibrosarcoma occurs most frequently in the mouth in dogs. The tumor is locally invasive, and often recurs following surgery.

Radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...

and

chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemother ...

are also used in treatment. Fibrosarcoma is also a rare bone tumor in dogs.

Cats

In cats, fibrosarcoma occurs on the skin. It is also the most common vaccine-associated sarcoma. In 2014,

Merial Boehringer Ingelheim Animal Health is a multinational animal health company, formed in January 2017 when Merial was acquired by Boehringer Ingelheim and merged with Boehringer Ingelheim's existing animal health assets. Overview In August 1997, ...

launched Oncept IL-2 in Europe for the management of such feline fibrosarcomas. Bostock DE, et al. performed a study of cats that had fibrosarcomas excised and were followed for a minimum of 3 years, or until death. Two factors, tumor site and mitotic index, were found to be of prognostic significance, but tumor size, duration of growth, and histologic appearance were not. Following removal of fibrosarcomas from the flank in 6 cats, none died as a result of the tumor but 24 of 35 (70%) cats with fibrosarcoma in the skin of the head, back, or limbs were euthanatized because of local recurrence, usually within 9 months of surgery.

References

External links

Fibrosarcoma of Bone: Review of a Rare Primary Malignancy of Bone

Atlas of Pathology
{{Osseous and chondromatous tumors Connective and soft tissue neoplasms Sarcoma Osseous and chondromatous neoplasia Cancer in cats Cancer in dogs