Fibrosarcoma (fibroblastic sarcoma) is a

malignant Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...

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 ever ...

tumour A neoplasm () is a type of abnormal and excessive growth of tissue (biology), 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 tiss ...

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

fibroblasts A fibroblast is a type of biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibrobla ...

or undifferentiated

anaplastic Anaplasia () is a condition of cells with poor cellular differentiation, losing the morphological characteristics of mature cells and their orientation with respect to each other and to endothelial cells. The term also refers to a group of mor ...

spindle cells in a

storiform pattern A woven or storiform pattern is a histopathologic architectural pattern. The name "storiform" originates , as storiform tissue tends to resemble woven fabric on microscopy. Storiform fibrosis is a histologic sign of IgG4-related disease, acco ...

. Fibrosarcomas mainly arise in people between the ages of 25 and 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 lo ...

and

Beta-catenin Catenin beta-1, also known as β-catenin (''beta''-catenin), is a protein that in humans is encoded by the ''CTNNB1'' gene. β-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 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. It is generally non-aggressive and amenable to surgical removal, tho ...

. 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 of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

, 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 is the most dangerous type of skin cancer; it develops from the melanin-producing cells known as melanocytes. It typically occurs in the skin, but may rarely occur in the mouth, intestines, or eye (uveal melanoma). In very rare case ...

, spindle cell

squamous cell carcinoma Squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, comprises 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 A leiomyosarcoma (LMS) is a rare malignant (cancerous) smooth muscle tumor. The word is . The stomach, bladder, uterus, blood vessels, and Gastrointestinal tract, intestines are examples of hollow organs made up of smooth muscles where LMS can be ...

, 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. Nerve sheath tumors can be benign or malignant, and may affect both the peripheral and central n ...

and biphenotypic sinonasal sarcoma.

Diagnosis

Ancillary testing for fibrosarcoma includes

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

, 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 Intermediate filament#Type III, type III intermediate filamen ...

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 ep ...

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 ...

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 (RT, RTx, or XRT) is a therapy, treatment using ionizing radiation, generally provided as part of treatment of cancer, cancer therapy to either kill or control the growth of malignancy, malignant cell (biology), ...

and

chemotherapy Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents or alkylating agents) in a standard chemotherapy re ...

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 corporation, 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. ...

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 three 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 six 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 euthanized because of local recurrence, usually within nine 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