What is a Histiocytoma?

These are usually angry looking, raised, hairless masses found on the skin of young dogs.
The most common areas are on the head, limbs and ears (often the front end of the body).
These are benign lesions and usually regress within a period of 3 months.

How to make a diagnosis:

Appearance
Age of the dog
Location
Cytology
Cytology is a very useful tool in diagnosing histiocytoma, the appearance is relatively typical.  Cytology also helps to exclude other growths which can look similar.
 

What to do once a histiocytoma is diagnosed:

Once we are confident that a lump is a histiocytoma and it is not causing distress, we tend to monitor them regularly and allow them to regress spontaneously – this usually happens in 6 to 8 week period.
However these masses can be very irritating or be associated with infections/reactions, or regression may not progress as expected – in which case medication or removal and histopathology is indicated.

Can’t we just leave all lumps to see if they disappear?

The simple answer is – this is a bad idea, and not in your pets best interests. There are many lumps that can look similar, some of these are very malignant, and the sooner they are removed the better. For example, mast cell tumours (MCT) are a very common and malignant tumour and can look exactly the same as a histiocytoma. We believe that using cytology helps us make choices that are in the best interest of your pets health at the early, and most important stage of evaluating tumours.