Cutaneous (skin) lymphoma is a cancer of lymphocytes, a type of white blood cell, that settles in the skin. In dogs it is a fairly uncommon form of lymphoma, and only a small share of all canine skin tumors turn out to be lymphoma. [2]
It can be hard to recognize. The red, scaly, crusty or itchy skin it causes looks a lot like other skin diseases, and in dogs it can resemble immune-mediated skin disease both on the outside and under the microscope. [1][2] If your pet has skin changes like the ones below, see your vet, who may suggest a biopsy (a small skin sample examined under the microscope). [1][4]
For other lumps and skin changes, see lumps and bumps on dogs and lumps and bumps on cats.
The two main forms
- Epitheliotropic lymphoma (also known as mycosis fungoides or cutaneous T-cell lymphoma): the cancer cells move into the outer layer of the skin (epidermis) and its structures, such as hair follicles. [4] In dogs it targets the haired skin and the edges where skin meets the lips, nose and eyelids (mucocutaneous junctions). [1]
- Nonepitheliotropic lymphoma: the cancer cells are found mostly in the deeper skin layer (dermis) and/or the tissue under the skin. [4]
Skin lymphoma in dogs
Which dogs get it
The epitheliotropic form mostly affects middle-aged to older dogs. [1] In a 2023 study of 176 dogs from the archives of the University of Pennsylvania and the University of Bern, the dogs came from 48 breeds and their mean age was 10.4 years. [5]
Signs
- Signs can include red, scaly or itchy skin, loss of color (depigmentation), sores (ulcers), crusts, hair loss, and raised plaques or lumps. They can show up on the haired skin, on the lips, nose and eyelids, on the footpads and inside the mouth. [1][2]
- In people the disease tends to move through set stages, from flat patches to thicker plaques to tumors. In dogs these changes can appear in any order. [2]
- In the 2023 study, the most common signs were redness (131 of 176 dogs), crusting (108) and scaling (102). Affected sites were the haired skin (159), lips (74), nose (49) and paw pads (48). [5]
- A 2018 study of 148 dogs divided epitheliotropic lymphoma into a skin (cutaneous) form and a form affecting the mucous membranes and the edges where they meet the skin (mucocutaneous/mucosal). [6]
- Some dogs develop many red lumps spread over the face, back and body, with smaller bumps on the belly. [2]
The nose and lips can also be affected by other conditions; see dry, crusty nose in dogs.
The nonepitheliotropic form in dogs
In this form the cancer cells sit deeper, in the dermis and the tissue under the skin, rather than in the outer layer, and a biopsy is how this form is told apart from the epitheliotropic one. [4]
Skin lymphoma in cats
- Skin lymphoma is uncommon in cats. In an Australian study of 1,705 cats with lymphoma, the skin was the main site in 44 of them (2.8%); the gut was by far the most common site. [3]
- A 2022 study of 41 cats with skin lymphoma from four veterinary teaching hospitals found a median age at diagnosis of 12.3 years. Most were domestic shorthair cats (29), and males were over-represented (30 of 41). Clinical signs and exam findings varied among the cats. [7]
How it is diagnosed
- Skin lymphoma is confirmed with a skin biopsy. The forms are told apart by where the cancer cells sit in the skin. [4]
- In dogs, early epitheliotropic lymphoma can be hard to tell apart from immune-mediated skin disease, even on a biopsy. In unclear cases, how the disease behaves over time and a second biopsy may be needed before the diagnosis is certain. [1]
- Your vet may also send samples for extra lab tests that look for a single cancerous group of lymphocytes. [1]
Treatment and outlook
- There is no standard treatment for epitheliotropic lymphoma in dogs, and treatment aims to ease the signs rather than cure it. [2]
- The outlook is generally poor, but the disease varies from slow and mild to fast and aggressive. [2]
- Your vet or a veterinary oncologist will choose any treatment; this guide does not give doses.
What studies report. Outcomes vary between studies:
- In the 2018 study of 148 dogs, the overall median survival time was 264 days (skin form: 130 days; mucous membrane form: 491 days). A single lesion had a better outlook, and the skin form and multiple lesions were linked to shorter survival. In dogs with multiple skin lesions, chemotherapy, retinoid treatment and complete remission were linked to longer survival. [6]
- In the 2023 study of 176 dogs, the median survival time was 95 days (range 1 to 850). Dogs treated with chemotherapy or with prednisone had longer median survival times than dogs given supportive care only. [5]
- A 2022 study of 46 dogs with cutaneous T-cell lymphoma found shorter overall survival with the epitheliotropic form (141 days) than with the nonepitheliotropic form (374 days). [8]
- In the 2022 cat study, 20 of the 34 treated cats responded to treatment (partial response or complete remission). The authors noted that the small number of cats limited what the study could show. [7]
These studies looked at groups of pets. A link between a treatment and longer survival does not prove the treatment caused it, and group figures cannot predict how one pet will do. Your vet can explain what they mean for your pet.
When to see your vet
- Red, scaly or crusty patches or plaques on your dog’s skin. [1][5]
- Sores, raised areas or lumps in or under the skin of your dog or cat. [2][4]
- Changes on the lips, nose, eyelids or footpads, or inside the mouth. [1][5]
- Any new skin change on an older cat. [7]
FAQ
What does skin lymphoma look like in dogs?
Signs vary and may include red, scaly or crusty skin, itching, loss of skin color, sores, hair loss, plaques or lumps, on the haired skin, the lips, nose, eyelids, footpads or inside the mouth. [1][2][5]
Can skin lymphoma look like allergies?
It can look like other red, itchy, scaly skin diseases, and in dogs it can resemble immune-mediated skin disease. [1][2] That is why a biopsy matters.
How is skin lymphoma diagnosed?
With a skin biopsy; the forms are told apart by where the cancer cells sit in the skin. [4] Early cases in dogs sometimes need a second biopsy. [1]
Do cats get skin lymphoma?
Yes, but it is uncommon; in cats lymphoma is found far more often in the gut than in the skin. [3][7]
The bottom line
Skin lymphoma is an uncommon cancer of lymphocytes in the skin. [2] In dogs, the epitheliotropic form affects middle-aged to older dogs and can look like other skin diseases, so a biopsy is needed to tell. [1] There is no standard treatment, and care aims to ease the signs rather than cure the disease. [2] See your vet about skin changes like these.
This article is for general information and is not a substitute for a veterinary exam. If you are worried about your pet’s skin, see your veterinarian.
Sources
- Gerber N, Brunner MAT, Jagannathan V, Leeb T, Gerhards NM, Welle MM, Dettwiler M. Transcriptional differences between canine cutaneous epitheliotropic lymphoma and immune-mediated dermatoses. Genes (Basel). 2021;12(2):160. doi:10.3390/genes12020160. Open access (CC BY). https://pmc.ncbi.nlm.nih.gov/articles/PMC7912288/
- Lee GW, Song SB, Kang MH, Park HM. Clinical response to isotretinoin and interferon-α of two dogs with cutaneous epitheliotropic T-cell lymphoma: a case report. BMC Vet Res. 2018;14(1):382. doi:10.1186/s12917-018-1710-y. Open access (CC BY). https://pmc.ncbi.nlm.nih.gov/articles/PMC6278019/
- Bennett P, Williamson P, Taylor R. Demographics of feline lymphoma in Australian cat populations: 1705 cases. Vet Sci. 2024;11(12):641. doi:10.3390/vetsci11120641. Open access (CC BY). https://pmc.ncbi.nlm.nih.gov/articles/PMC11680128/
- Rook KA. Canine and feline cutaneous epitheliotropic lymphoma and cutaneous lymphocytosis. Vet Clin North Am Small Anim Pract. 2019;49(1):67-81. doi:10.1016/j.cvsm.2018.08.007. PMID 30262145. https://pubmed.ncbi.nlm.nih.gov/30262145/
- Dettwiler M, Mauldin EA, Jastrebski S, Gillette D, Stefanovski D, Durham AC. Prognostic clinical and histopathological features of canine cutaneous epitheliotropic T-cell lymphoma. Vet Pathol. 2023;60(2):162-171. doi:10.1177/03009858221140818. PMID 36541607. https://pubmed.ncbi.nlm.nih.gov/36541607/
- Chan CM, Frimberger AE, Moore AS. Clinical outcome and prognosis of dogs with histopathological features consistent with epitheliotropic lymphoma: a retrospective study of 148 cases (2003-2015). Vet Dermatol. 2018;29(2):154-e59. doi:10.1111/vde.12504. PMID 28983988. https://pubmed.ncbi.nlm.nih.gov/28983988/
- Siewert J, Pellin MA, Husbands BD, Curran KM, Scavelli D, Sampene E. Feline cutaneous lymphoma: an evaluation of disease presentation and factors affecting response to treatment. J Feline Med Surg. 2022;24(4):389-397. doi:10.1177/1098612X211028837. PMID 34284671. https://pubmed.ncbi.nlm.nih.gov/34284671/
- Azuma K, et al. Outcomes and prognostic factors in canine epitheliotropic and nonepitheliotropic cutaneous T-cell lymphomas. Vet Comp Oncol. 2022;20(1):118-126. doi:10.1111/vco.12752. PMID 34250731. https://pubmed.ncbi.nlm.nih.gov/34250731/