Results - Aprocrine or Sweat Gland Cyst

Update since the discovery and decision to have surgery for lump on tail and picking her up from surgery.

Received the results from the lab today on my phone. It read:

"Rainbow's histology report shows a sweat gland cyst.
Further complications unlikely. Dr Compion"

A quick Googling shows that :
Apocrine or Sweat Gland Cyst – The development of apocrine cyst is generally harmless. They are operated in very rare cases when they are found to be causing any serious health problem. Apocrine cysts are generally left on their own till they are cured on their own. But you must be sure enough that the tumor is actually an apocrine sweat gland and not apocrine adenocarcinoma. An apocrine adenocarcinoma is actually the form of malignant cancer and looks almost similar to apocrine cyst. On close examination the color of the apocrine appears to be light blue or purplish while the apocrine adenocarcinoma has the color of dark blue or almost black. 
taken from http://www.petcaregt.com/dogcare/doggrowths.html

Rainbow is back to normal - active again. But her appetite is still huge!

Current photo of the tail  *sorry it's blur-ish!*