Mammary diseases Flashcards
Which dog breed might be predisposed to malignant mammary tumors?
German shepherds

What is the relative likelihood of malignant mammary tumors in dogs?
- Most common neoplasm in intact female dogs
- 70% of all tumors (benign and malignant)
- 50% malignant in dogs
Do multiple tumors occur commonly?
Yes– > 60%
Why do all mammary tumors need to be removed?
Malignant transformation is possible
“Watch and wait” is NEVER appropriate
EVER
NEVER EVER

Why should each mammary tumor be tested histopathologically?
- Different histologic subtypes in the same dog
- Each mass should be submitted
What are some differences between hyperplasia and neoplasia?
- Hyperplasia will regress on its own while neoplasia will not
- Hyperplasia occurs after heat cycle due to progestin
- ID by history and pattern of masses
- More likely to see hyperplasia in young dogs than neoplasia
- Multiple little tiny masses throughout chain indicative of hyperplasia
Which tests are indicated for work-up?
- Minimum database (CBC/chem/UA)
- 3 view thoracic rads
- Abdominal U/S, CT, or MRI
- Biopsy
Why is it necessary to include 3-way thoracic rads in the workup?
- 25-50% of malignancies have metastasis at initial diagnosis
- Presence of metastasis makes good prognosis unlikely
When is/isn’t abdominal US/CT/MRI indicated for the workup?
- Especially for caudal mammary tumors
- Drainage to the iliac LN
- Not necessary for small, single masses
Why is a biopsy recommended for workup?
- Only way to differentiate malignant vs. benign
- Excisional biopsy usually diagnostic of choice
Is cytology valuable in the workup of mammary tumors?
- Questionable value
- Cannot definitely rule out malignancy
- Treatment for benign tumors is identical
- Differentiate mammary from other (e.g. mast cell tumor)
- FNA of LN if palpable
What criteria is associated with malignancy in mammary tumors?
- Rapid growth (history)
- Size (> 0.5cm diameter)
- Fixed to skin or underlying tissues/invasive
- Poorly circumscribed
- Ulceration or inflammation
T/F: Even single, small masses should always be removed
TRUE–NEVER WATCH AND WAIT

Benign masses can become malignant
What are the appropriate margins for wide excision of a potentially malignant tumor?
2-3cm margin circumference
If invasive: fascia and muscle plane deep
When is a lumpectomy indicated?
Only appropriate if no criteria of malignancy
Periphery of gland or between glands only
What is a simple mastectomy? When is it indicated?
Removal of single, entire mammary gland
Solitary mass within 1-2cm of gland
When is a regional mastectomy indicated?
For multiple tumors in adjacent glands
What are the indications for a chain mastectomy?
- Multiple masses throughout the chain
- Tumors in gland 3 with any COM–variable lymphatic drainage
- Solitary masses anywhere with multiple COM
Explain the lumpectomy procedure
- Mass removed with 1cm margins
- Mass should be between glands or near periphery
- Incision into gland–>leakage of lymph–>inflammation
Explain the procedure of a simple mastectomy
- Elliptical incision includes entire mammary gland
- If mass is in middle of gland this ensures 2-3cm margins
- Ensures complete removal of malignancy
- Elliptical incisions easier to close
Explain the procedure of a regional mastectomy
- “Regional” = same lymphatic/vessel drainage
- Remove glands cranial and caudal to mass
- Glands 1-3 for tumors in glands 1 & 2
- Glands 3-5 for tumors in glands 4 & 5
- Superficial inguinal node removed with gland 5
What is special about gland 3 when performing regional mastectomy? When would you need to perform a chain mastectomy instead?
- Gland 3 has unpredictable lymphatic drainage
- If tumor is in gland 3 and simple masectomy is not indicated, must perform chain mastectomy
What is a chain mastectomy? When should it not be performed?
- Removal of the entire chain of mammary glands
-
Do not perform if animal has metastasis
- Not worth the surgery/complications
Why is regional mastectomy rarely used?
60% of dogs have recurrence on the same side

