Common tumor type arising from glandular epithelial tissue.
Prognosis: depends on site.
Treatment: variable response to chemotherapy, surgery and/or radiation therapy which are the mainstays of treatment.
In general malignant tumors/adenocarcinomas are much more common than benign adenomas/adenomas.
Adenocarcinomas occur in the skin (sweat gland and ceruminous gland), oropharynx, nasal chamber, salivary gland, stomach, intestine, bile duct, gall bladder, mammary gland, larynx, trachea and lung.
Adenomas occur in the skin (sweat gland), oropharynx, intestine, bile duct, mammary gland, kidney and thyroid gland.
Adenocarcinomas are locally invasive and depending on site metastasize to local and distant sites
Adenomas are non-invasive and do not metastasize.
Presenting signs
Depends on site.
Adenocarcinomas are often locally invasive and may be ulcerated.
Adenomas are small, well defined and non-ulcerated.
Sweat gland adenocarcinomas often occur on head and neck.
Ceruminous gland adenocarcinoma in external and middle ear canal.
In the gastrointestinal tract adenomas are rare, adenocarcinomas common, majority occur in small intestine (ileum or jejunum), causing diarrhea and/or vomiting, rarely in the stomach.
Bile duct adenomas and adenocarcinomas occur with similar frequency and present with cranial abdominal mass/hepatomegaly and signs of vague malaise and jaundice.
Mammary adenocarcinomas often originate from the caudal two mammary glands. The mass may be ulcerated. There may be signs of tumor metastasis, eg dyspnea due to pulmonary metastasis.
FeLV unlikely to be associated with intestinal adenocarcinoma.
Pathophysiology
Malignant adenocarcinomas/adenocarcinomas much more common.
Adenocarcinomas are generally locally invasive and often metastasize to local and distant sites.
Gastrointestinal metastatic disease is usually abdominal.
Tumor behavior
Sweat gland and ceruminous gland adenocarcinomas - locally invasive, metastasis not common, to lungs, lymph nodes, liver, digits.
Salivary gland adenocarcinoma - limited studies suggest cure with excision followed by radiation therapy.
Mammary tumors - 90% are adenocarcinoma and are aggressive. Systemic metastasis can occur - to lymph node, pleura, lung, liver, spleen, kidneys. Metastatic potential depends on size and histology.
Pulmonary adenocarcinoma - aggressive tumor.
Nasal adenocarcinoma - usually locally invasive but with low metastatic potential.
Intestinal adenocarcinomas often extend into mesentery. Distant metastasis to lymph nodes, spleen, lungs or kidney common in small intestinal adenocarcinomas, less common in large intestine.
Adenocarcinoma of feline intestine is usually at advanced stage, at the time of diagnosis some cats with confirmed lymph node metastasis have lived for average of 12 months following surgical resection of intestinal adenocarcinoma.
Chemotherapy not usually effective.
Combination chemotherapy using doxorubicin and cyclophosphamide has been shown to induce short-term response in about 50% of cases with non-resectable tumors or tumor metastasis.
nasal discharge, obstruction, sneezing.
