Fibrosarcoma (fibroblastic sarcoma) is a

malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

mesenchymal Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every o ...

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 A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells o ...

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 ...

spindle cells in a storiform pattern. 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 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 transcripti ...

) within this tumor are similar to those found in the cellular form of

mesoblastic nephroma Congenital mesoblastic nephroma, while rare, is the most common kidney neoplasm diagnosed in the first three months of life and accounts for 3-5% of all childhood renal neoplasms. This neoplasm is generally non-aggressive and amenable to surgical r ...

. 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 whole ...

, 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 A synovial sarcoma (also known as malignant synovioma) is a rare form of cancer which occurs primarily in the extremities of the arms or legs, often in proximity to joint capsules and tendon sheaths. It is a type of soft-tissue sarcoma. The name " ...

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 A nerve sheath tumor is a type of tumor of the nervous system (nervous system neoplasm) which is made up primarily of the myelin surrounding nerves. From benign tumors like schwannoma to high grade malignant neoplasms known as malignant peripheral ...

and biphenotypic sinonasal sarcoma.

Diagnosis

Ancillary testing for fibrosarcoma includes

IHC IHC may refer to: Medicine * Immunohistochemistry * Intrahepatic cholestasis Science and technology * Indirectly Heated Cathode, a type of hot cathode used in vacuum electronics tubes * Intelligent Home Control, home automation and control s ...

, 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 expressed ...

is positive,

cytokeratin Cytokeratins are keratin proteins found in the intracytoplasmic cytoskeleton of epithelial tissue. They are an important component of intermediate filaments, which help cells resist mechanical stress. Expression of these cytokeratins within epit ...

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 over ...

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. Radia ...

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. Chemotherap ...

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 A vaccine-associated sarcoma (VAS) or feline injection-site sarcoma (FISS) is a type of malignant tumor found in cats (and often, dogs and ferrets) which has been linked to certain vaccines. VAS has become a concern for veterinarians and cat owner ...

. 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