고양이 지방종 vs 악성 지방육종 자주 묻는 질문 Q&A — 보호자가 꼭 알아야 할 핵심

Soft Lumps: Benign or Malignant? — Key Q&A on Feline Lipomas and Liposarcomas

Oncology/CancerQ&AMeongsiljang Veterinary Advisory Board

Feline lipomas are benign tumors, but liposarcomas are malignant and invasive, with the potential to metastasize. An accurate diagnosis is essential.

What Are the Key Differences Between Feline Lipomas and Malignant Liposarcomas?

Feline lipomas are benign tumors that develop under the skin. They typically grow slowly and are characterized by being soft and easily movable. While common in dogs, they are relatively rare in cats. - Lipoma: These usually grow slowly without causing pain. If encapsulated, complete surgical removal can lead to a cure. However, infiltrative lipomas, although benign, grow by spreading between muscle fibers, which can lead to frequent local recurrence. - Malignant Liposarcoma: This is a malignant tumor that can grow invasively. Incomplete excision carries a high risk of local recurrence, and metastasis is possible. - Malignant Liposarcoma: These tend to grow rapidly, feel fixed rather than movable, and may be associated with pain. Although lipomas and liposarcomas can look similar externally, they are difficult to distinguish without a definitive diagnosis. Histological examination is essential. Early detection is key to successful treatment.

Comparison images of feline lipoma and malignant liposarcoma

Why Is It Important to Accurately Distinguish Between the Two Tumors?

Lipomas, which are encapsulated fatty tumors, are usually cured without recurrence when completely removed through surgery. However, malignant liposarcomas can recur or metastasize after surgery, making early diagnosis crucial for saving lives. - Lipoma: Treatment is straightforward, and the prognosis is generally good. However, infiltrative lipomas, even though benign, can be difficult to completely excise, leading to frequent local recurrences. - Malignant Liposarcoma: The treatment scope is broader, and if excision is incomplete, the risk of local recurrence increases, so radiation or chemotherapy may be used in combination. Misdiagnosis can delay treatment and threaten life. Accurate diagnosis is the starting point for treatment planning. We strongly recommend a biopsy when visiting the hospital.

The process of fine-needle aspiration for feline subcutaneous tumors

When Should You Visit the Vet?

Lumps under a cat’s skin warrant careful attention. You should definitely visit a vet if the lump grows relatively quickly, feels fixed to the skin or deeper tissues rather than moving freely, causes pain, or shows signs of infiltrating between muscle layers. - Lipoma: These typically grow slowly, are painless, and move easily under the skin. However, even though infiltrative lipomas are benign, they can grow between muscle layers. - Malignant Liposarcoma: These may grow rapidly, feel fixed in place, and be accompanied by redness or ulceration of the skin. Early diagnosis is crucial for successful treatment. Ignoring the issue can make treatment more difficult, and delaying a vet visit increases the risk.

Symptoms of feline subcutaneous malignant liposarcoma

Signs That Require an Immediate Vet Visit

If the lump grows relatively quickly, causes pain, limits movement, or causes the skin to become red or flaky, you should visit the vet immediately. These could be signs of a malignant liposarcoma. Early diagnosis is key to successful treatment.

What Tests Are Needed for an Accurate Diagnosis?

Ultrasound helps assess the tumor’s depth, boundaries, and blood flow. However, a tissue biopsy is essential for a definitive diagnosis. - Fine-needle aspiration (FNA): This method is quick and simple, but its accuracy may be limited. - Surgical biopsy: This involves complete removal of the tissue for pathological examination, enabling an accurate diagnosis. The results determine the treatment plan. Accurately determining whether the tumor is malignant is crucial for appropriate treatment. Your veterinarian strongly recommends this test.

A scene of a cat undergoing an ultrasound examination.

How Do Treatment Methods Differ?

Encapsulated lipomas are usually cured by surgery alone, as the tumor can be completely removed. However, infiltrative lipomas may recur even though they are benign, because complete excision is difficult. Malignant liposarcomas may require a wider surgical margin, and sometimes radiation therapy or chemotherapy in addition to surgery. - Lipoma: The encapsulated type has a very low recurrence rate after surgery. - Malignant liposarcoma: The risk of recurrence increases with a wider area of invasion or incomplete excision. The treatment plan depends on the tumor’s size, location, and extent of invasion. Discuss with your veterinarian to determine a personalized treatment plan. Early intervention is important.

Consultation scene for a treatment plan for feline malignant liposarcoma

Comparison Table: Lipoma vs. Malignant Liposarcoma

Item	Lipoma	Malignant Liposarcoma
Nature	Benign	Malignant
Growth rate	Very slow	Fast
Invasiveness	Usually none (infiltrative type invades between muscles)	High
Metastatic potential	None	Present
Treatment method	Surgical removal	Surgery + radiation/chemotherapy

An accurate diagnosis should be made through a tissue biopsy.

Caution: Misjudgment Can Be Life-Threatening

Even if you suspect it’s a lipoma, there’s a chance it could be malignant if it’s growing or feels fixed in place. It’s safest to have a biopsy done before deciding on surgery. Be sure to discuss the situation thoroughly with your veterinarian and develop a treatment plan together.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Are lipomas common in cats?

Lipomas are very common in dogs but relatively rare in cats. They are benign tumors that typically appear in older animals and are usually discovered incidentally, as they rarely cause any symptoms.

Is malignant liposarcoma treatable?

Yes, with early diagnosis and appropriate treatment, we can expect a good outcome. However, if the surgical removal is incomplete, the risk of local recurrence is high, so consistent follow-up care is essential.

Do lipomas grow?

Although they grow slowly, these masses can enlarge over time, potentially restricting movement or causing pain. Infiltrative lipomas, in particular, can spread into the surrounding tissues.

Can a lipoma become cancerous?

Lipomas are benign tumors and are unlikely to become malignant on their own. Malignant liposarcomas are a separate type of cancer, so it is important to perform a biopsy to differentiate between the two if the mass grows or changes in character.

How long does recovery take after surgery?

The recovery period varies depending on the tumor size and the extent of surgical resection, and the surgical site should be closely monitored for signs of infection. Please consult your veterinarian for detailed guidance on your pet’s progress.

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References

[1] Veterinary Surgical Oncology, 2nd Edition. 2018. Wiley-Blackwell.

[2] BSAVA Manual of Canine and Feline Dermatology, 4th Edition. 2020. BSAVA Publications.

[3] Clinical Medicine of the Dog and Cat, 4th Edition. 2019. Elsevier.