Are Those Lumps Hard or Soft? What Cats’ Cancerous Growths Can Tell You


Cats can develop various types of lumps, masses, and tumors. Some are benign (non-cancerous), while others are malignant (cancerous). Lumps are a common symptom of cancer in cats. According to the American Veterinary Medical Association (AVMA), cancer is a leading cause of death in older cats, with over 90 million cats at risk.

Some of the most common cancers in cats include lymphoma, mast cell tumors, mammary cancer, and soft tissue sarcomas. These cancers can produce visible or palpable lumps on or under the skin. However, not all lumps are cancerous. Some may be harmless growths or abscesses.

It’s important for cat owners to monitor their pet’s body and alert the vet about any new lumps or bumps. An examination and tests are needed to diagnose the cause and determine if it is benign or malignant. Early detection and treatment is key for managing feline cancers.

Types of Cancer in Cats

Some of the most common cancers diagnosed in cats include:

  • Lymphoma – This cancer affects the lymph nodes and white blood cells. It accounts for up to one third of all cancer diagnoses in cats. (
  • Squamous Cell Carcinoma – This skin cancer often occurs on the nose, ears or eyelids of white or light colored cats. It’s the second most common feline cancer. (
  • Mammary Tumors – Tumors in the mammary glands are seen predominantly in unspayed female cats. They account for 17% of feline cancers. (
  • Mast Cell Tumors – These tumors involving mast cells in the skin or internal organs represent up to 20% of skin tumors in cats. (

Other cancers like fibrosarcomas, melanomas, and oral squamous cell carcinomas are also occasionally seen in cats. With early detection and treatment, cats can live for years after a cancer diagnosis.

Symptoms of Cancer

One of the most common symptoms of cancer in cats is the development of lumps or masses on or under the skin. These lumps can be benign or malignant. Benign lumps are non-cancerous growths that typically do not spread or metastasize to other areas of the body. Malignant lumps signal cancerous tumors that can be life-threatening if left untreated.

Lumps caused by cancer may appear suddenly and begin growing quickly. The lumps may feel firm or solid upon palpation. However, some malignant tumors can also feel soft and squishy. Lumps can develop anywhere on the body including the legs, head, abdomen, and spine. Other accompanying symptoms may include lameness if the lump interferes with mobility, lethargy from cancer spread, and decreased appetite.

Some of the most common forms of feline cancers that produce lumps include lymphoma, mast cell tumors, mammary cancer, and soft tissue sarcomas. It is important to have any new lumps or growths on a cat evaluated promptly by a veterinarian. Early detection and diagnosis is key for successful treatment and prognosis (

Characteristics of Benign vs Malignant Lumps

There are some key differences between benign (non-cancerous) and malignant (cancerous) lumps in cats that can help determine the likelihood of cancer:

Feel: Benign lumps often feel soft and movable under the skin. Malignant lumps tend to feel very firm or hard.

Mobility: Benign lumps can usually be moved around under the skin and are not attached to underlying tissues. Malignant lumps are generally fixed in place and immovable.

Appearance: Benign lumps tend to have distinct edges and smooth surfaces. Malignant lumps often have irregular or poorly defined borders and an abnormal surface texture.

In general, benign lumps are soft, movable, and well-circumscribed, while malignant lumps are hard, fixed, and irregularly shaped. However, exceptions occur, so veterinary examination is required for an accurate diagnosis.


Lymphoma is one of the most common cancers in cats, often seen in middle-aged to older cats. It affects the lymphocytes, which are a type of white blood cell vital to the immune system Lymphoma in cats frequently presents as lumps or masses in areas such as the neck, chest, and abdomen as the cancerous lymphocytes proliferate These lumps may grow rapidly over the course of days or weeks and can vary in texture. Lymphoma tends to spread throughout the body as opposed to staying localized in one area.

Mast Cell Tumors

Mast cell tumors are a type of skin cancer that originates from mast cells in the skin, which are involved in the immune system response. These tumors commonly appear as raised, firm lumps on the skin that range from soft to hard in texture. According to the VCA Animal Hospitals, mast cell tumors can feel like soft, movable lumps under the skin or appear as very firm/hard masses adhered to the underlying tissues.1 The tumors are often hairless and may ulcerate or become infected. They can develop anywhere on the body, but are most commonly found on the head, neck, and limbs.

While some mast cell tumors are benign, others can be malignant and metastasize to other areas of the body. One sign of how aggressive the cancer is relates to lump firmness. According to PetMD, very soft or fluid-filled masses are lower grade tumors, while firm, nodular masses that feel fixed in place tend to be higher grade tumors with a greater risk of spreading.2 So both soft and hard lumps can indicate mast cell cancer, but hardened masses are more concerning.

Mammary Cancer

Mammary cancer in cats is common among middle-aged and older felines with approximately 85% of feline mammary tumors being malignant (1). Mammary cancer, also known as mammary carcinoma or mammary adenocarcinoma, occurs due to abnormal, uncontrolled growth of cells in the mammary glands (2).

The most notable symptom of mammary cancer is palpable nodules or masses along the mammary line on a cat’s belly. These tumors may start small but can grow quickly in size. The lumps may be soft, spongy, firm, or hard in texture. Some feline mammary tumors have a characteristic ulcerated appearance (3). While some cancers will remain localized to the primary tumor site, in the case of mammary adenocarcinoma, metastasis often occurs to nearby lymph nodes and vital organs like the lungs.

Diagnosis is made via biopsy of the tumor mass. Treatment typically involves surgical removal of the tumor(s) as well as chemotherapy and supportive care. Early detection and treatment are key for the best prognosis.


Soft Tissue Sarcomas

Soft tissue sarcomas are a type of cancer that originates in the connective tissues like fat, muscle, nerves, fibrous tissues, blood vessels, deep skin tissues, and cartilage[1]. In cats, they most commonly arise under the skin and can present as soft or hard lumps. Approximately 90% of soft tissue sarcomas in cats occur at vaccination sites or sites of previous injury[2].

The most common types of soft tissue sarcomas in cats are fibrosarcomas, liposarcomas, peripheral nerve sheath tumors, and myxosarcomas. They are locally invasive and tend to recur after surgical removal, but usually do not spread to other parts of the body. However, they can occasionally metastasize to the lungs, spleen, and lymph nodes[3].

On physical exam, soft tissue sarcomas often present as subcutaneous nodules that are freely movable underneath normal skin. They can range from soft and fluid-filled to very firm. Some may only be detected as ill-defined thickenings under the skin surface. Their appearance can help distinguish them from benign tumors like lipomas, but a biopsy is required for a definitive diagnosis.

Diagnosing Lumps

A veterinarian must conduct a thorough physical examination of the cat’s lump in order to determine if it may be cancerous. The vet will visually inspect and palpate the lump, noting its size, texture, mobility, and location on the body[1]. Firm, fixed lumps that are rapidly growing are more suspicious for malignancy. The vet will also check for enlarged lymph nodes which can indicate cancer[2].

If cancer is suspected, the vet will recommend a biopsy to analyze cells from the lump[1]. This can be done by fine needle aspiration or surgical biopsy. Cytology is another diagnostic test where cells are collected and examined under a microscope[2]. These tests help differentiate between benign masses like fat deposits versus cancerous tumors.

Advanced imaging such as x-rays, ultrasound, CT scan or MRI can also aid diagnosis by evaluating the lump’s attachments and internal structure[1]. These imaging modalities help stage cancer and plan for surgery if needed. Catching feline cancers early is key, so diagnostic testing is critical.


The treatment for cancerous lumps in cats depends on the type of cancer and how advanced it is. Some of the main treatment options include:

Surgery – Surgery is commonly used to remove localized tumors or cancerous lumps if they have not yet spread to other areas. Completely removing the lump and margins of healthy tissue gives the best chance for a cure.

Chemotherapy – Many types of cat cancers, such as lymphoma, can be treated successfully with chemotherapy drugs. Cats tend to tolerate chemotherapy well with minimal side effects.

Other treatments like radiation therapy, immunotherapy, and targeted therapies may also be options depending on the type and stage of cancer. Determining the optimal treatment plan involves evaluating the type of cancer, how far it has advanced, the cat’s age and health status, and other factors.

Treating cancer in cats aims to remove or destroy cancerous cells while preserving quality of life. Early detection and treatment provide the best chances for remission and long-term survival.

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