Malignant fibrous histiocytoma (MFH) (synonyms: Fibrohistiocytic tumors; fibroxanthosarcoma; myxofibrosarcoma; soft tissue sarcoma; ICD-10-GM C49.9: Malignant neoplasm of other connective tissue and other soft tissue, unspecified) is a malignant (malignant) neoplasm (neoplasm) of soft tissue, bone tissue, and skin. It belongs to the group of soft tissue sarcomas.Typical of an MFH is that it does not have a clearly assignable cell differentiation.
The following forms of malignant fibrous histiocytoma are distinguished:
- Primary malignant fibrous histiocytoma – cause unknown.
- secondary malignant fibrous histiocytoma (approximately 20% of cases) – due to a preexisting tissue lesion such as a/s:
- Of the following underlying diseases:
- Enchondroma (benign (benign) bone tumor arising from cartilage tissue).
- Fibrous dysplasia (malformation of bone tissue, that is, the bones form tumor-like protrusions).
- Bone fracture (bone fracture)
- Bone infarction (demise of bone tissue).
- Paget’s disease (disease of the skeletal system with bone remodeling).
- Osteomyelitis (inflammation of the bone marrow)
- Surgical intervention
- For MFH of the skin:
- In scar tissue
- In sites of chronic inflammation
- In irradiated areas (radiatio; radiotherapy).
- Of the following underlying diseases:
Sex ratio: males are affected approximately twice as often as females.
Peak incidence: malignant fibrous histiocytoma occurs predominantly between the ages of 20 and 70, with men often developing the disease between the ages of 40 and 60 and women between the ages of 20 and 30.
Malignant fibrous histiocytoma is the third most common (11%) soft tissue sarcoma. Overall, however, it is a very rare malignant neoplasm of adulthood.
The incidence (frequency of new cases) for MFH of the extremities as well as the retroperitoneal type (retroperitoneum = space located behind the peritoneum on the back toward the spine) is 8.8 cases per 1,000,000 population per year and for dermal/cutaneous MFH < 0.5 per 1,000,000 population per year (in Germany).
The course and prognosis depend on the location, extent, and stage of the bone tumor. It is true that “the earlier the tumor is detected, the better the chances of cure”. Malignant fibrous histiocytoma grows relatively slowly, but often behaves very aggressively, forming hematogenous (“via the bloodstream”) and lymphogenous (“via the lymphatic pathway”) metastases to the regional lymph nodes (4-17%) (31-35% of cases). Distant metastasis (the spread of tumor cells from the site of origin via the blood/lymphatic system to a distant site in the body and the growth of new tumor tissue there), especially pulmonary (“to the lungs”; 90%), and rarely osseous (“to the bones“; 8%) or hepatogenic (“to the liver“; 1%), can also be observed. In many cases, the tumor has already “spread” at the time of diagnosis. It must be surgically removed. This is usually followed by radiatio (radiation therapy), and possibly chemotherapy.
Malignant fibrous histiocytoma has a tendency to recur. The local recurrence rate ranges from 19 to 31%.
The prognosis of malignant fibrous histiocytoma is poor (for prognostically unfavorable parameters, see “Consequelae/Prognosis Factors” below).
The 5-year survival rate for malignant fibrous histiocytoma is 58-77%. The 5-year survival rate of retroperitoneal tumors is 15-20%.
The 10-year survival rate of low-grade malignant fibrous histiocytoma is 90%, that of intermediate-grade malignant fibrous histiocytoma is 60%, and that of high-grade malignant fibrous histiocytoma is 20%.
