Home » Diseases » In dogs » Malignant Fibrous Histiocytoma (Soft Tissue Tumors)

Malignant Fibrous Histiocytoma (Soft Tissue Tumors) in Dogs

Occurrence: rarer
Location of disease: General/Whole body

Author: Dr. med. vet. Gisa Löwe | Last modified: 17.02.2026

When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

If the condition worsens / symptoms persist, consult a veterinarian.

Definition

MalignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. Fibrous Histiocytoma (MFH) is a rare, malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. soft tissue tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. in dogs, characterized by aggressive growth and a high tendency to metastasize.

The most important facts at a glance

Malignant Fibrous Histiocytoma (MFH) is an aggressive soft tissue tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. in dogs that arises from mesenchymal precursor cells. The exact causes are unclear, but genetic factors, environmental influences, and chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. inflammatory conditions could play a role. Older dogs are more frequently affected. Symptoms include swelling, pain, and loss of appetite. DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made through clinical examination, biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions., and imaging procedures such as X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions. or MRI to assess the extent and possible metastasesA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body..

Treatment often requires surgical removal of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions., supplemented by radiation therapyRadiation therapy is the use of radiation, most often to treat cancer. It can be used to kill cancer cells or slow their growth without significantly damaging surrounding healthy tissue. or chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. in metastatic cases. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is guarded to poor, especially with metastatic tumors. Regular follow-up checks are important to detect recurrences early. Since the exact causes are not fully understood, there are no specific preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. measures. Nevertheless, regular veterinary examinations and avoiding carcinogens can lower the overall cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. risk.

Research focuses on the genetic basis of MFH to develop more targeted treatments. New diagnostic methods and forms of treatment such as immunotherapy are being investigated. A healthy lifestyle could have a supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. effect, and studies on the role of nutrition could offer new therapeutic approaches.

Causes

Malignant fibrous histiocytomas belong to the sarcomas, a group of tumors originating from mesenchymal cells. These cells are the precursors of connective tissue, muscle, fat, and other soft tissues. MFH is characterized by a mixture of fiber-forming and histiocytic (macrophage-like) cells. The exact cell line from which MFH originates is not fully understood, but it is assumed that the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. cells derive from undifferentiated mesenchymal precursor cells.

The causes for the development of a malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma are not fully understood. Genetic factors, environmental influences, as well as chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. inflammatory conditions or traumas could play a role in tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. development. There are no specific breed predispositions, but older dogs are more frequently affected.

Genetic mutations that lead to uncontrolled cell division are often the driving force behind tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. development. These mutations can occur spontaneously or be induced by external influences such as environmental toxins or radiation. However, the exact genetic signature of MFH in dogs is still a subject of research.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

Lethargy

Symptoms of a malignantMalignant means “cancerous” and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma can vary depending on the location and size of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions.. The tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. often appears as a fast-growing, painless lump in the subcutaneousSubcutaneous means “under the skin.” In medicine, it refers to the administration of drugs or the placement of implants directly under the skin. tissue. However, it can also occur in deeper soft tissues and exert pressure on surrounding structures there.

In advanced stages, symptoms such as lameness, swelling, weight loss, and general weakness can occur. MetastasesA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body., especially to the lungs, can lead to respiratoryRespiratory refers to breathing or the process of breathing. Respiratory diseases affect the respiratory tract and can impair the ability to breathe effectively. distress. In some dogs, systemic symptoms such as fever or anemia can also be observed, indicating a malignantMalignant means “cancerous” and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. disease.

Since the symptoms are non-specific, it is important to see a veterinarian for any new or unusually fast-growing lump to get an accurate diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients..

Diagnosis

The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of a malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma begins with a thorough clinical examination and medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits.. Since the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. often appears non-specific externally, further diagnostic procedures are required to make an accurate diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients..

A biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions. of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. tissue is the most important diagnostic measure. Tissue samples are taken and examined histopathologically. Microscopic examination typically shows a mixture of spindle and histiocytic cells with high mitotic activity, indicating the aggressiveness of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions..

Imaging procedures such as X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions., ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow., or MRI can be used to assess the extent of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. and possible metastasesA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body.. A chest X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions. can help detect lung metastasesA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body., which are common in MFH.

Therapy

The treatment of malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma requires a multimodal approach. Surgical removal of the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. is the primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. treatment option. An attempt must be made to completely remove the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. with sufficient safety margins to minimize the likelihood of recurrence.

In cases where complete surgical resection is not possible, radiation therapyRadiation therapy is the use of radiation, most often to treat cancer. It can be used to kill cancer cells or slow their growth without significantly damaging surrounding healthy tissue. can be used to destroy the remaining tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. cells. ChemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. may be considered, especially for metastatic tumors or if surgical removal was not complete. However, the effectiveness of chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells. for MFH is limited and depends on the individual tumor biology.

Treatment is often palliativePalliative refers to treatments that aim to alleviate the symptoms of a disease without curing the disease itself. Palliative care focuses on improving the quality of life of patients with incurable diseases., especially for metastatic or inoperable tumors, and aims to improve the animal’s quality of life and relieve symptoms.

Prognosis and follow-up care

The prognosis for dogs with a malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma is generally guarded to poor, especially if the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. has metastasized or cannot be completely removed surgically. Survival time depends on various factors, including tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. size, location, metastasisA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body., and the dog’s overall health.

Dogs where the tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. could be completely removed and that show no signs of metastasisA metastasis is a secondary tumor that originates from a primary, malignant tumor in another part of the body. Metastases indicate that cancer has spread in the body. have a better prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop.. Nevertheless, the recurrence rate is high, and regular follow-up checks are necessary to detect a recurrence early.

The dog’s quality of life is paramount in treatment, and decisions should be made in the best interest of the animal, weighing the burden of treatment against the quality of life.

Prevention

Since the exact causes for the development of a malignant fibrous histiocytoma are not fully understood, there are no specific preventive measures to prevent the occurrence of these tumors.

However, regular veterinary check-ups and early detection of tumors can help improve the prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop.. Monitoring older dogs for unusual swelling or lumps and prompt clarification by a veterinarian are important for identifying malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. tumors early.

Avoiding known carcinogens and maintaining a healthy lifestyle, including a balanced diet and regular exercise, can reduce the overall cancer risk in dogs, even if they do not represent specific preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. against MFH.

Outlook on current research

Research on malignantMalignant means "cancerous" and is used to describe tumors or neoplasms that grow invasively and have the ability to metastasize. Malignant tumors can cause serious health problems in dogs and cats. fibrous histiocytoma (MFH) in dogs is constantly evolving, as it is an aggressive form of soft tissue sarcomaA sarcoma is a malignant tumor that originates from supporting and connective tissues such as bone, adipose tissue, muscles, or blood vessels. Sarcomas can occur in dogs and cats and require aggressive treatment. that occurs in both humans and animals. Currently, many studies are focusing on better understanding the genetic and molecular basis of these tumors. Researchers are investigating specific mutations and genetic markers that could contribute to the development of MFH to develop more targeted and effective treatment strategies. Identifying such genetic anomalies could make it possible to develop personalized therapies that are better tailored to the individual needs of each dog.

Another focus of research is the improvement of diagnostic procedures. Currently, MFH is often diagnosed through a combination of imaging and biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions., but there are efforts to develop less invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. methods. Advances in imaging technology, such as the use of high-resolution MRIs and CT scans, could significantly improve the accuracy of diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and help detect tumors at an earlier stage. In addition, work is being done on the development of biomarkers that can be detected in the blood to facilitate the monitoring and management of the disease.

Therapeutic approaches are also an important area of research. Traditionally, MFH tumors are treated by surgical removal, often in combination with radiation therapyRadiation therapy is the use of radiation, most often to treat cancer. It can be used to kill cancer cells or slow their growth without significantly damaging surrounding healthy tissue. and chemotherapyChemotherapy refers to the treatment of diseases, especially cancer, with chemical substances or drugs. It aims to kill cancer cells or prevent their growth, but can also affect healthy cells.. However, current studies are investigating the potential of newer forms of treatment such as immunotherapy and targeted therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions.. Immunotherapies use the body’s own immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. to attack cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. cells, while targeted therapies attack specific anomalies in the cancerCancer refers to the uncontrolled proliferation of cells that can lead to tumors or spread throughout the body. Various types of cancer occur in dogs and cats, ranging from skin cancer to lymphomas. cells. By combining these methods with traditional forms of treatment, researchers hope for improved outcomes for affected dogs.

In veterinary medicine, the role of nutrition and overall health in the treatment of MFH is also being investigated. A healthy lifestyle could play a supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. role in the treatment and possibly also in the preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of tumors. Studies investigating the influence of diet and nutritional supplements on tumorA tumor is an abnormal growth of tissue that can be benign or malignant. Tumors can develop in any part of the body and affect various functions. growth in dogs could provide valuable insights and lead to new supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. therapeutic approaches.

Frequently asked questions (FAQs)

What is a Malignant Fibrous Histiocytoma?

A malignant fibrous histiocytoma (MFH) is a type of malignant tumor that arises from soft tissues. These tumors are aggressive and can grow quickly and spread to other parts of the body. They occur in both humans and dogs. -

What symptoms does a dog with MFH show?

Symptoms can vary depending on the location of the tumor, but often include swelling or masses under the skin, lameness, pain, or general signs of discomfort such as loss of appetite and weight loss. -

How is MFH diagnosed in dogs?

Diagnosis is usually made through a combination of physical examination, imaging (such as X-ray, ultrasound, CT, or MRI), and a biopsy of the tumor to perform a histological examination. -

What treatment options are available for dogs with MFH?

The primary treatment is usually surgical removal of the tumor, often followed by radiation therapy or chemotherapy to destroy remaining cancer cells and prevent recurrence. -

What is the prognosis for dogs with MFH?

The prognosis depends on various factors, including the size and location of the tumor, the stage at diagnosis, and the chosen treatment. In general, the prognosis is guarded because MFH is aggressive and has a tendency to metastasize. -

Can MFH tumors be prevented in dogs?

There are no specific measures to prevent MFH, as the exact causes are not fully understood. However, a healthy lifestyle and regular veterinary check-ups can help detect tumors early. -

Are there breeds that are more susceptible to MFH?

MFH can theoretically occur in any dog breed, but some studies indicate that larger dog breeds may have a higher risk. Further research is required to better understand genetic predispositions. -

Is MFH painful in dogs?

Yes, MFH can be painful, especially if the tumor grows near nerves or in joints. Pain can also come from metastases or secondary effects of the tumor. -

What role does nutrition play in the treatment of MFH?

A balanced diet can support a dog's general well-being and possibly strengthen the immune system, which can be helpful in fighting cancer. However, there is no specific diet known to directly influence MFH. -

How can I help my dog with MFH?

Ensure your dog receives regular veterinary check-ups and follows the recommended treatment. Support your dog with a balanced diet, appropriate exercise, and plenty of love and attention to improve their quality of life.