kitten lump

Question
I have an 18 week old female kitten. It seems like overnight she developed a nickel-sized, ball-shaped cyst right below her shoulder blade next to her spine. It moves around when you touch it and it doesn't hurt her, i don't even think she's noticed. Does this sound like it could be harmful or cancerous?  

Answer
Hi Emily.  Did your kitten recently have her vaccinations?  It sounds like this lump COULD be a reaction to her FVRCP vaccine.  This vaccine protects against feline distemper, calici virus and feline herpes and is given in the right shoulder.  If the location fits, it may just be a vaccine site reaction.  The good news is that this vaccine is not typically linked to cancer like the rabies or feline leukemia vaccines are.  Most swellings in response to the injection go away within a couple of weeks.

However, any lump should be brought to the attention of the vet.  Cancer is uncommon in kittens this young but is still possible.  Lumps could indicate infections under the skin, bug bites, allergic reactions, or they might be fluid-filled cysts or fatty tumors.  These sebaceous cysts and fatty tumors, called lipomas, are non-cancerous and are not harmful.  It is generally advised not to treat them.