Why some lumps matter and others don’t (warning: gory pictures!)

I often get asked if I can tell what a lump is just from a hands-on examination. There’s no certainty in life but in most cases we can get a good idea what’s going on, and classify them into high, medium and low risk.

Soft “domed” lumps under the skin on older dogs, usually carrying some middle aged spread, can usually be diagnosed as low risk “lipomas” or fatty lumps with little further investigation. Sometimes something isn’t quite right…

Derv came in to see us with a small lump on his back. His owners and I were concerned as to its nature, so we decided to do a biopsy by removing the lump and sending it to the lab. The lump appeared to be a reasonably low risk benign skin tumour with very clear edges; if lumps are suspected of being something more sinister then usually we try to submit just a few cells so as to leave them relatively undisturbed. “Operate once and operate well” as my old surgery professor used to boom at us.

Here’s how Derv looked after we’d done the biopsy:

The lab report made for unsettling reading; Derv was suffering from a moderately aggressive “mast cell” tumour. This is a cancer of cells found in the skin- left untreated this could become more malignant, spread to other organs and eventually kill him. Unfortunately they tend to spread invisibly through the skin around the lump, so it looked like major surgery to attempt a cure. We needed to extend the incision to a 2.5cm radius of clear skin all the way around the original site, and go down to the muscle layers. This meant a fist sized hole in his side- how could we close the wound afterwards? Here was our plan:


Here’s our first incision:


So far so good:


The four incisions to the sides are part of a plastic surgery technique known as an H-plasty. Two advancement flaps are raised either side to bring across and close the site.
Stitches going in:


The final result: (the white concertina is an active surgical drain which was left in for 24 hours)

10 days post operation, the stitches are all out, the wound’s healing well and Derv’s a happy man:


…and I hear today he’s completely back to his normal self and just waiting for the hair to grow back!