Page 1247 - Cote clinical veterinary advisor dogs and cats 4th

624 Mammary Gland Neoplasia, Dog

• Signs of malignancy include fixation to skin • Inguinal/axillary lymphadenopathy (reactive, • Goal is to remove all tumor by simplest
surgical procedure that ensures clean margins.
neoplastic)
or underlying structures, rapid increase in • Inguinal hernia • Unilateral radical chain mastectomy decreases
VetBooks.ir inflammation, and edema. Initial Database the chances of tumor development in the
size, ill-defined borders, ulceration, pain,
remaining mammary tissue. In one study,
○ Absence of these signs does not exclude
malignancy.
○ Measure primary tumor (T).
• Inflammatory carcinomas present with • Physical exam 58% of dogs that underwent a regional
mastectomy for a solitary mammary tumor
diffuse, firm, and painful swelling of the ○ Describe possible signs of invasiveness developed a new tumor in the ipsilateral
affected gland or chain. The adjacent extrem- (ulceration, fixation). mammary chain after the first surgery.
ity may be affected. Cutaneous involvement ○ Evaluation of regional lymph nodes (N): • Remove inguinal lymph nodes with
in the form of small, beadlike nodules may palpation and cytologic study caudal gland tumors; excise axillary nodes
be found. • CBC, serum biochemistry profile, urinalysis only if metastasis is suspected; always
• Regional lymph nodes (inguinal and axil- • Thoracic radiographs (three views) submit all excised tissue for histologic
lary) may be enlarged (due to metastasis or • Abdominal ultrasound in case of suspected assessment.
reactive hyperplasia) or normal on palpation. metastasis to abdominal organs or lymph • Inflammatory carcinoma is nonresectable;
The internal iliac, popliteal, sternal, and nodes palliative surgery may be possible in select
prescapular nodes may also be affected. • Coagulation profile in cases of suspected cases.
inflammatory carcinoma (risk of DIC)
Etiology and Pathophysiology Chronic Treatment
• Estimated malignancy rates: 30%-50% Advanced or Confirmatory Testing • Chemotherapy: limited information available
• Tumors metastasize most commonly to the • Biopsy of the tumor and thorough histologic ○ Antitumor activity has been demon-
regional lymph nodes and lungs, although exam are necessary to obtain a definitive strated in vitro in selected patients with
liver and bone metastases are frequently diagnosis. gross metastatic disease and as adjuvant
described. ○ Fine-needle aspiration for cytologic exam treatment in a small group of dogs with
• Tumors are classified according to their tissue of mammary masses may help distinguish advanced-stage disease. Dogs with tumors
of origin as epithelial, mesenchymal, and nonmammary tumors (lipomas, mast at high risk for metastasis may benefit
mixed tumors. cell tumors) from mammary tumors, from adjuvant chemotherapy.
○ Inflammatory carcinoma is not a specific although cytologic findings alone may ○ Chemotherapeutics studied for monother-
histologic subtype but an aggressive, not be helpful in distinguishing benign apy include doxorubicin, 5-fluorouracil,
high-grade carcinoma with invasion of from malignant mammary tumors. cyclophosphamide, taxanes, and platinum
the dermis and dermal lymphatics. The • Incisional biopsy may not represent the compounds (i.e., cisplatin or carbopla-
inflammatory cell infiltrate is moderate in whole tumor but is recommended before tin). Special handling requirements and
most cases and consists of lymphocytes, excisional biopsy if malignancy is not initially potentially severe, life-threatening adverse
plasma cells, and macrophages. suspected. patient effects exist for these drugs.
• Primary mesenchymal mammary tumors (e.g., • Lymph node metastasis: fine-needle aspira- ○ COX2 inhibition with nonsteroidal anti-
fibrosarcoma, osteosarcoma) are uncommon. tion and cytologic evaluation of lymph inflammatory drugs may have anticancer
Malignant mesenchymal mammary tumors nodes has been shown to increase diagnostic activity.
often behave aggressively, with frequent accuracy of mammary tumor metastasis. • OHE at time of mammary tumor surgery:
metastasis and a short survival time. Metastases may be present in palpably normal benefit is controversial, with some studies
• Mixed mammary tumors consist of epithelial, nodes. reporting increased survival and others
myoepithelial, and mesenchymal tissue. • Advanced imaging (CT, MRI [p. 1132]) may showing no difference.
Benign mixed mammary tumors (fibroepithe- be more sensitive for detecting metastatic • Radiation therapy: limited information is
lial) and malignant mixed mammary tumors lesions in the thoracic and abdominal cavities available; may be of use in the palliative
(carcinosarcoma) have been described. and should be considered when metastasis setting or to improve local control in inoper-
• Complex mammary tumors include epithelial is suspected but cannot be detected on able cases
and myoepithelial components. radiographs or ultrasound. • Anti-estrogen therapy (tamoxifen): not
• Cyclooxygenase 2 (COX2) is overexpressed in recommended. Most anaplastic mammary
most mammary carcinomas. Prostaglandin E 2 TREATMENT tumors lack estrogen receptors, and anti-
(PGE 2 ), the product of COX2, may promote estrogen therapy may not be beneficial for
tumor development and angiogenesis/ Treatment Overview most cases in which systemic therapy is
metastasis. COX-2 inhibitors may play a Treatment consists of complete surgical removal indicated. Estrogen-like side effects, including
role in tumor control.. of the mammary tumor(s). The role of chemo- vulvar swelling, vaginal discharge, stump
therapeutics in delaying the onset of metastatic pyometra, signs of estrus, and urinary tract
DIAGNOSIS disease has not been well defined in dogs. For infection may occur.
dogs with inoperable tumors or inflammatory • Pain medication: analgesics should be
Diagnostic Overview carcinomas, palliation with antiinflammatory considered in the palliative treatment of
The diagnosis is suspected based on finding medications may improve quality of life. advanced-stage disease or inflammatory
a mass in the mammary chain. Histologic carcinoma. Options include nonsteroidal
evaluation is required for definitive diagnosis. A Acute General Treatment antiinflammatories (including carprofen 2
diagnostic and treatment approach is presented • Mainstay of treatment is surgical excision of mg/kg PO q 12h, deracoxib 1-2 mg/kg PO
on p. 1434. sufficient width to completely remove the q 24h, meloxicam 0.1 mg/kg PO q 24h,
mammary tumor(s). firocoxib 5 mg/kg PO q 24h, or piroxicam
Differential Diagnosis • Type of surgery (nodulectomy, regional or 0.3 mg/kg q 24h).
• Mastitis radical mastectomy) depends on the size,
• Dermatitis location, and number of tumors. Recommended Monitoring
• Fibroepithelial hyperplasia ○ Type of surgery does not influence survival Regular exam of surgical site and local lymph
• Other cutaneous and subcutaneous tumors, as long as the entire tumor is removed nodes: radiology or other imaging techniques
including benign lipoma with histologically clean margins. if indicated (e.g., diagnosis of malignancy,

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