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Lumps and Bumps

Over the course of the past 6 months Beebee's mother had noticed several small lumps developing on and under Beebee's skin. She says that Beebee seems to be in good health otherwise.


10-year-old spayed Rottweiller mix, "BeeBee"


Over the course of the past 6 months Beebee's mother had noticed several small lumps developing on and under Beebee's skin. She says that Beebee seems to be in good health otherwise.


Beebee was alert and responsive at the time of her examination. Examination of her musculoskeletal, cardiovascular and gastrointestinal systems was non-remarkable.

Beebee had four skin lumps. On the back side of her neck there was a 2-3 cm firm subcutaneous lump with a palpable stalk extending into the deeper tissues. At the base of her left ear and at the point of her left shoulder were two 1-2 cm hairless pigmented soft cutaneous masses. The final lump was located on the back surface of her left hind leg at the level of the knee. This lump was 1 cm in diameter and firm.


All lesion were presumed to be skin tumors based on their appearance.


Beebee's owner was advised that the lumps were tumors of some variety and should be tested to try to more specifically identify them prior to definitive treatment. Fine needle aspiration of all masses was performed using a 20 gauge needle. Samples were then submitted to a pathology lab for identification. In addition, CBC and blood chemistry were also performed.


The CBC and chemistry revealed no abnormalities. Cytological evaluation of the lumps was suggestive of some form of melanoma on the shoulder and ear. A connective tissue tumor, likely malignant, was identified on the sample from the neck region. Aspirates from the back of the left leg were non-diagnostic.


Beebee was returned for surgical removal of all lumps. Because the lump on the neck had been identified as a likely malignancy, a wide, aggressive resection was performed removing the lump with 2 cm skin margins and a deep margin one-tissue plane beyond the apparent limit of the mass. The other masses were removed with less aggressive margins and all samples were submitted for biopsy and margin evaluation. Beebee rec /langs/en.js" type="text/javascript"> overed uneventfully from her procedure and went home the same evening.


The mass from the neck was identified as a fibrosarcoma, a malignancy with locally aggressive tendencies. Margins were greater than 1 cm in all planes and surgical excision was deemed adequate.

Both the lump from the ear and the shoulder were identified as malignant melanomas. The shoulder lesion was deemed adequately excised, while the mass from the ear was considered a marginal surgical excision based on margins of less than 5mm in one plane.

The lesion on the hind limb were identified as a benign growth arising from the glands of the hair follicles.


Beebee's case illustrates the importance of early evaluation of skin lumps in dogs and cats. On initial examination, our clinical impression of the lumps was that the lump on the neck was likely to be malignant, that the lumps near the ear and on the shoulder were likely to be benign and that the lump by on the hind limb was of concern. All skin lumps should be evaluated by fine-needle aspiration without exception. This is a simple, non-invasive relatively painless outpatient procedure of immense value. The accuracy is about 75-90%, depending on the size and nature of the skin lesion. Small lesions that are poorly exfoliating may yield ambiguous or possibly erroneous results. As with Beebee, even educated clinical impressions can be incorrect. The fact that a tumor is movable and is not attached to deeper tissues is not a valid means of assessing its potential for malignancy. Microscopic evaluation by a trained pathologist is the most accurate means of determining a tumor's nature. This knowledge is important in developing an effective surgical plan so that a single surgery can be curative rather than finding out after surgery that the excision was inadequate and having to subject the pet to a second procedure.

In addition, any tumor of questionable identity or previously deemed malignant on cytology should be submitted for a full biopsy when it is excised. This should include identification of tumor type as well as evaluation of surgical margins to assess the adequacy of the excision.

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