Mysterious lump found on Rocky

Rocky is a 6 year old Boxer, one of the dignified gentlemen of the Boxer world. A little shy but always a pleasure to meet.

As he has gotten older, Rocky has developed a couple of little skin growths that have always been tested and appear to be just “skin tags”. Recently however, Rocky came in for a check-up because his owners had discovered another lump on his tummy that was quite different to the rest. The lump had developed over a couple of weeks and seemed to be quite red and raised off the skin. Whilst Rocky did not seem bothered by the lump, his owners wisely sought to have it checked, particularly because Boxers can be prone to a variety of skin lumps, some nastier than others.

On examination, Rocky had a 1.5cm diameter red raised mass on his abdomen that appeared to be merging into the skin at its margins. A fine needle aspirate sample was taken of the lump as a simple diagnostic test. The vet team are able to assess lumps for cells and cell changes that might be characteristic for certain types of skin cancers. A lot of the time, however, a fine needle sample cannot tell us exactly what type of cancer might be present. In Rocky's case, the lump appeared to have “round cells”, cells with a circular shape and round nucleus. The nucleus is the area of the cell that contains all the genetic information of the cell. We were able to determine that there were multiple cells of different size and some of the cells appeared to be preparing their DNA to divide. These two changes can be indications of cancerous processes occurring. Cancer cells divide and grow uncontrollably, thus many different sizes of the same type of cell can be seen.

Although there were some changes suggestive of a cancerous process, some inflammatory skin lumps can look very similar. These inflammatory lumps tend to improve with anti-inflammatory medication and disappear with time. To rule these out, we decided to trial Rocky on some anti-inflammatories.

Unfortunately, the lump did not reduce much in size or disappear on the medical trial. We recommended surgical removal of the lump. As with any condition, treating early is always better than delaying treatment. With skin lumps, the size of the lump greatly influences the extent of surgery that needs to be performed. A lump that has grown in size means additional surgical trauma to remove it completely. In some cases, extra skin may need to be moved in the form of a skin flap or skin graft to cover the surgical wound. This means a much larger wound and more discomfort for our patients. Rocky's owners were keen to have the lump removed quickly. Additionally, we decided to send the lump off to the laboratory to work out what type of cells we were dealing with.

Rocky's surgery procedure was performed without a hitch. We were able to remove the lump with one centimeter margins of skin around the mass and one tissue plane below the lump. No extra manipulation of the skin was required as surgery was performed early in the course of the disease, before the lump had grown too much in size. The lump was submitted to the laboratory for analysis.

The biggest benefit of submitting a lump to the laboratory is that we are usually able to determine what kind of cells make up that lump. From there, the vets can give you an idea of the behaviour of those cells, whether they tend to be aggressive, spread to other parts of the body, come back after removal or if surgical removal is a permanent fix. Pathologists also give us an idea of the 'margins of excision', the amount of healthy tissue with no cancer cells that surround the lump. When clean margins are achieved, no cancer cells are seen in the tissue around the lump, reducing the likelihood that cells have been left behind. Cancer cells left behind in the skin, or any other tissue, have the tendency to grow back even more aggressive than they were before. Because of this, the first attempt at surgical removal is always our best chance of a cure.

The lump that Rocky had was quite unusual with many changes that meant that, visually, the pathologists could not determine the exact cell type of the lump. What we did manage to determine was that the surgery had achieved clean margins around and under the lump, and that there was definite evidence of cancerous change in the cells. Further testing would be required to check for cell markers by immunohistochemistry to differentiate the likely cell types. Rocky's very conscientious owners were keen to get to the bottom of this lump and allowed us to request the additional testing as it meant that we could either get peace of mind regarding the lump or we would be able to pick the most appropriate additional treatment for Rocky.

The pathologists' report came in the next day with a diagnosis of a plasma cell tumour, a cancer of the B-lymphocyte white blood cell line. These tumours are generally benign and do not require further treatment when removed with clean margins. This was great news for Rocky! Whilst we still need to keep a very close eye on his skin and lymph nodes, the likelihood is that we should have no further issues with the lump. Rocky's owners were delighted with the news.

Rocky's case highlights the benefits of achieving an accurate diagnosis when it comes to lumps and bumps. In addition, early treatment improves our chances of removing a lump completely and achieves a quicker diagnosis. Getting a final diagnosis means that the vets can make the most appropriate recommendation when it comes to further treatment.

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