What is this tumor?
This tumor is a disordered and purposeless overgrowth of sweat gland cells. Most sweat glands are attached to the hair follicles (paratrichial) but a few are not associated with follicles (atrichial). Most sweat gland tumors are benign and can be permanently cured by total surgical removal. Malignant tumors that spread to other parts of the body are rare.
What do we know about the cause?
The reason why a particular pet may develop this, or any cancer, is not straightforward. Cancer is often seemingly the culmination of a series of circumstances that come together for the unfortunate individual.
We do not know precisely what causes these tumors. Induction of cancer is a multi-step process called tumor progression. The majority of sweat gland cancers never progress past the first stages and are technically hyperplasias (overgrowths) rather than true, out-of-control cancers. Hyperplasia and benign tumors (adenomas and complex adenomas) grade into each other.
Is this a common tumor?
The tumors are uncommon. They are usually found in animals over six years of age but can occur earlier. Malignant tumors are rare and when they do occur tend to be in slightly older animals.
On the eyelid, these tumors are frequently multiple. The proximity of the eye makes full excision difficult.
How will this tumor affect my dog?
These tumors are usually noticed as lumps and the main problems are physical because of the size and sites. They are often cystic and may ulcerate and bleed or become secondarily infected. Tumors may be painful if they have ruptured because sweat is irritant.
The malignant tumors (adenocarcinomas) are locally aggressive. Distant metastasis only occurs after some time.
How is the tumor diagnosed?
Clinically, these tumors resemble other tumors of the skin. They may be dark in color so can be mistaken for other tumors. Diagnosis relies upon microscopic examination of tissue. Needle aspiration for microscopic examination of cell samples (cytology) may be helpful for rapid or preliminary tests but is less diagnostic than histopathology. Histopathology is the microscopic examination of specially prepared and stained tissue sections. This is done at a specialized laboratory where the slides are examined by a veterinary pathologist. The information from this examination also enables more accurate prediction of behavior (prognosis) and a microscopic assessment of whether the tumor has been fully removed. Histopathology also rules out other cancers.
The diagnosis includes words that indicate whether a tumor is "malignant’. Malignancy is often shown by the word ending "carcinoma’.
What treatment is available?
Treatment is surgical removal of the lump. If this is then sent for histopathological diagnosis, the diagnosis can be confirmed, the completeness of excision assessed and other diagnoses ruled out.
Can this tumor disappear without treatment?
Tumors very rarely disappears without treatment. Very occasionally, spontaneous loss of blood supply to the cancer can make it die but the dead tissue will still need surgical removal. The body’s immune system is not effective in causing this type of tumor to regress.
How can I nurse my dog?
Preventing your pet from rubbing, scratching, licking or biting the tumor will reduce itching, inflammation, ulceration, infection and bleeding. Any ulcerated area needs to be kept clean.
After surgery, the operation site similarly needs to be kept clean and your pet should not be allowed to interfere with the site. Any loss of sutures or significant swelling or bleeding should be reported to your veterinarian.
How will I know if the tumor is permanently cured?
’Cured’ has to be a guarded term in dealing with any tumor.
Histopathology will give your veterinarian the information that will help to indicate how the tumor is likely to behave. The veterinary pathologist usually adds a prognosis that indicates the probability of local recurrence or metastasis (distant spread).
Hyperplasias and benign tumors can be cured by surgery. The rare malignant tumors can usually be cured surgically as well as metastasis is unusual and rarely occurs at an early stage of the cancer.
Are there any risks to my family or other pets?
No, these are not infectious tumors and are not transmitted from pet to pet or from pets to people.
Based on material written by Joan Rest, BVSc, PhD, MRCPath, MRCVS. and modified with permission from Lifelearn Inc.
© Copyright 2004 Lifelearn Inc.
