Definition and overview

Malignant fibromatous neoplasm is a cancerous tumour that originates from the fibrous connective tissues of the bone. Also known as fibrosarcoma, it is one of the three types of cancers that share similar traits known as sarcomas, along with osteosarcoma and chondrosarcoma. It is characterised by the proliferation of fibroblasts in the bones, wherein the cells of the bones divide excessively and uncontrollably. Fibroblasts can invade local tissues such as overlying muscles, fat, blood vessels, and joints. They can also spread even to distant sites in another form of the disease known as metastatic fibrosarcoma.

Fibrosarcoma cancer commonly affects bones that are long and flat, such as the femur, tibia, and the mandible, but it can also sometimes develop on the bones of the head and neck. The disease presents in different degrees of severity, namely low-grade fibrosarcoma, immediate malignancy, and high malignancy. A sclerosing epithelioid fibrosarcoma, one of the rarer types of the disease, is one example of a low-grade fibrosarcoma.

Causes of Condition

Fibrosarcoma makes up 5% of all primary bone sarcomas. It is more common among males but can also affect females. It typically occurs between the ages of 25 and 79. It can affect both adults and infants, resulting in two manifestations of the disease:

  • Adult fibrosarcoma – Adult fibrosarcoma often affects middle-aged adults between 35 to 50 years old. Most of them experience pain as a result of the disease.

  • Infantile fibrosarcoma – Infants may also be affected with fibrosarcoma, but in most cases, the disease is congenital. The disease often presents in the first two years of life. This type of the disease, however, is quite rare.

Fibrosarcomas, regardless of whether it affects the bone or soft tissues, are believed to be linked to radiation exposure. Thus, they are more common among patients who have previously had radiation radiation therapy for unrelated cancer.

Another risk factor for developing malignant fibromatous neoplasm is an earlier bone disease, such as Paget’s disease or osteomyelitis, as well as other low-grade lesions such as chondrosarcoma. These lesions increase a person’s risk of developing secondary fibrosarcoma.

Key Symptoms

Fibrosarcoma symptoms include:

  • Pain

  • Swelling

  • Firm lump under the skin or on the bone

  • Broken bone

  • Restricted range of motion

  • Gastrointestinal bleeding, if fibrosarcoma develops on soft tissue in the abdominal region

  • Increased urinary frequency

  • Urinary obstruction, if fibrosarcoma develops in the pelvic region

There are certain barriers to the early diagnosis of fibrosarcoma. Patients who experience pain, swelling, and a restricted range of motion sometimes mistake their symptoms as those caused by arthritis or even minor trauma. These symptoms are rarely immediately associated with a tumour. In many patients, firm lumps and broken bones are stronger indicators that eventually prompt them to seek medical treatment.

Although fibrosarcoma can easily be detected through an x-ray, it may also be challenging to diagnose as a malignant fibromatous neoplasm because it shares most histological features with other types of bone tumours. Several similarities have also been noted between fibrosarcoma and malignant fibrous histiocytoma. As such, it often takes experienced musculoskeletal pathologists to distinguish malignant fibromatous neoplasms from other similar bone lesions. During this process, the patient may need to undergo various tests and scans, including computed tomography (CT) and magnetic resonance imaging (MRI) scans, an angiogram, and a biopsy. These are more advanced tests used to guide treatment. For example, an MRI is helpful in determining the extent of soft tissue and bone marrow involvement – important information that doctors need to plan the best course of treatment for the patient. CT scans, on the other hand, can be performed on various parts of the body to check for metastasis. A chest CT scan is often performed as the lungs is the most common site of metastatic sarcoma.

Who to See and Types of Treatments Available

Fibrosarcoma is treated the same way as other types of bone tumours, with the primary treatment option being complete excision of the tumour. During surgery, the surgeon will also remove an adequate margin of healthy tissue that surrounds the tumour to make sure no malignant cells are left behind. After the surgical excision, patients will need to undergo further cancer treatment, such as chemotherapy, radiation therapy, irradiation, or brachytherapy.

If the tumour is very large to begin with, patients typically undergo chemotherapy first to shrink the tumour. This will make it easier for the surgeon to remove the entire tumour during surgery.

Patients with fibrosarcoma are managed by a multidisciplinary team of medical professionals including medical, radiation, and surgical oncologists, as well as pathologists, dietitians, physical therapists, and occupational therapists.

Fibrosarcoma prognosis depends on many factors, particularly the size, location, and the stage of cancer. The chances of successful treatment are higher among those with local tumours. Treatment is more challenging for those who have metastatic disease, or when malignant fibromatous neoplasm has already spread to distant sites. Secondary fibrosarcoma is known to have very poor outcomes, with only a 10% 10-year survival rating. This means that only 10% of patients with metastatic fibrosarcoma survive up to 10 years following diagnosis.

In comparison to other types of bone sarcomas, fibrosarcoma prognosis is worse than that of osteosarcoma. It currently has a 65% 5-year survival rating and a 30% 10-year survival rating for high-grade fibrosarcomas of the bone while soft-tissue fibrosarcoma has a 40 to 60% 5-year survival rating.

Infantile fibrosarcoma has a relatively higher 5-year survival rating of 80% and long-term survival rating of 50%.

Despite successful treatment, patients who have had malignant fibromatous neoplasm are at risk of recurrences.


  • Krygier J, Lewis V. “Fibrosarcoma of Bone: Review of a Rare Primary Malignancy of Bone.” ESUN.

  • Dickey ID. “Fibrosarcoma.” 2016. Medscape.

  • “Fibrosarcoma.” 2002. Gale Encyclopedia of Cancer.

  • Antonescu CR, Rosenblum MK, Pereira P, Nascimento AG, Woodruff JM. “Sclerosing epithelioid fibrosarcoma: a study of 16 cases and confirmation of a clinicopathologically distinct tumour.” 2001. Am J Surg Pathol. Jun;25(6):699-709.

Share This Information: