Every nerve runs inside a wrapping of connective tissue called the nerve sheath. Tumors can grow from the cells of this wrapping. Vets group them into benign types (such as neurofibromas and schwannomas) and a malignant type, the malignant nerve sheath tumor, sometimes called a neurofibrosarcoma [2]. The same family also includes neuromas that form where a nerve has been cut [1][4]. Dogs and cats can both get them, and in cats they mostly turn up in the skin and the tissue just under it [3].
In the skin, these tumors look like many other lumps. Telling them apart takes a sample from the lump, checked in a lab [1][2].
Have your vet check any new lump on your pet’s skin.
Neurofibromas and neurofibrosarcomas
These tumors are made of long, spindle-shaped cells that come from the nerve sheath [1][2].
- Age: soft tissue sarcomas, the group that includes the malignant nerve sheath tumor, are seen mostly in middle-aged and older dogs [1]. In one study of 68 dogs with nerve sheath tumors, the median age was 8 years [2].
- Look: a lump in or under the skin. In a study of 53 cats, the tumors were found in the skin, the layer below it, muscle or the lining of the mouth and nose, and three out of four were on the head, neck or legs [3].
- Benign or malignant: both forms exist [2][3]. In that cat study, most tumors were benign and about a quarter showed signs of malignancy [3]. The malignant form belongs to the soft tissue sarcoma group [1]. For that group of tumors, see soft tissue sarcoma in dogs.
In dogs, a nerve sheath tumor can be hard to tell apart from a perivascular wall tumor, the group that includes the hemangiopericytoma. A 2026 veterinary oncology consensus notes that some experts question where these tumors really start, that they are often hard to separate under the microscope, and that the two share more genetic features with each other than with fibrosarcomas [1].
Amputation neuromas after tail docking
When a nerve is cut, the cut end can grow into a tangled lump of nerve tissue called a neuroma [4]. Neuromas have been found in the tail stumps of docked dogs [4]. A review of tail docking notes reports of dogs chewing at their tail stumps one to four years after docking, which suggests a painful neuroma may keep drawing the dog’s attention to the area [4].
How vets diagnose them
Your vet may start with a fine needle sample of cells from the lump. This is a useful first screen, but with these spindle-cell tumors it often cannot give a firm answer: in one study of 40 dogs it was inconclusive or did not match the final result in more than a third of cases [1]. The consensus says a firm diagnosis always needs a tissue sample (a biopsy) examined by a pathologist, and it advises a biopsy before removing a large lump or one that may be hard to remove fully [1]. Telling a malignant nerve sheath tumor from other sarcomas, or from a benign nerve sheath tumor, can be difficult even for pathologists [2].
For other lumps your vet may consider, see lumps and bumps on dogs and lumps and bumps on cats.
Treatment
Your vet will advise on treatment for your pet.
- Neurofibromas and neurofibrosarcomas: surgery is the standard treatment. The aim is to take out the whole tumor with a rim of normal-looking tissue around it, so the lab can confirm nothing was left behind [1]. When the edges are narrow or tumor cells remain, radiation therapy after surgery can help control regrowth [1]. Chemotherapy is not a routine first treatment and is kept mostly for high-grade tumors or tumors that have spread [1].
- Amputation neuromas: your vet can advise on the options for a painful tail stump.
At home, as directed by a vet:
- note the size, place and date of any lump, so you can show your vet any change;
- do not squeeze or try to drain a lump;
- go back for every recheck.
Outlook
Most soft tissue sarcomas in dogs are low grade. They tend to grow into the tissue around them, but their chance of spreading to distant parts of the body is fairly low; the risk is higher for high-grade tumors [1]. In the cat study, tumors came back after removal in 9 cases, and none was recorded as having spread [3].
These are statements about groups of animals. They cannot predict how one pet will do. Your vet can explain what this means for your pet.
When to see your vet
See your vet if your dog or cat has:
- a new lump in or under the skin, especially in an older pet [1][3];
- a lump that comes back after it was removed [3];
- a docked tail that your dog keeps chewing or bothering [4].
FAQ
Is a nerve sheath tumor cancer?
It can be either. There are benign and malignant forms [2][3]. Only a lab result from a sample can tell which one your pet has.
Is this the same as a hemangiopericytoma?
Not quite, but in dogs the two can be very hard to tell apart, and experts still debate how closely they are related [1].
Can I tell a nerve sheath tumor from other lumps by touch?
No. Many skin lumps look and feel alike, and even a needle sample is often not enough [1]. Your vet takes a sample to know.
The bottom line
Nerve sheath tumors grow from the connective tissue wrapping around a nerve and show up as lumps in or under the skin of dogs and cats, often in older dogs. There are benign and malignant forms. Surgery to remove the whole tumor is the standard treatment. Only a lab sample tells these from other lumps, so have your vet check any new lump.
This article is for general information only and does not replace advice from your veterinarian. If your pet has a new lump, see your vet.
Sources
- Fonseca-Alves CE, Biondi LR, Dos Anjos DS, et al. Canine cutaneous and subcutaneous soft tissue sarcoma in dogs: a consensus report from the Brazilian association of veterinary oncology. Frontiers in Veterinary Science. 2026;13. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC13192336/
- Tekavec K, Švara T, Knific T, et al. Loss of H3K27me3 expression in canine nerve sheath tumors. Frontiers in Veterinary Science. 2022;9:921720. CC BY. https://pmc.ncbi.nlm.nih.gov/articles/PMC9372589/
- Schulman FY, Johnson TO, Facemire PR, Fanburg-Smith JC. Feline peripheral nerve sheath tumors: histologic, immunohistochemical, and clinicopathologic correlation (59 tumors in 53 cats). Veterinary Pathology. 2009;46(6):1166-80. PubMed abstract. https://pubmed.ncbi.nlm.nih.gov/19605904/
- Mellor DJ. Tail docking of canine puppies: reassessment of the tail’s role in communication, the acute pain caused by docking and interpretation of behavioural responses. Animals. 2018;8(6):82. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC6028921/