Let's talk about Histo, baby

Fungal is my favorite. Is that weird to say?

This case is from a 2 year old cat with intermittent lethargy. 

On presentation he had several non-healing cutaneous wounds, mostly focused on his carpi and tarsi. 

He was prescribed antibiotics, but then returned when the wounds persisted. 

On re-presentation, the vet did an impression smear of one of the open sores. 

This is what we saw:

Histoplasma! 

One of the reasons I like fungal infections is that when you find the organism, it's like solving a mystery. 

We now know this cat has a fungal infection causing his wounds - and the culprit is Histoplasma capsulatum! 

Side note: Sporothrix (known in the human world as "Rose Gardener's Disease") can look very similar to histoplasma on cytology. However, Sporothrix yeast are typically elongated/oblong. They don't have to be though, so it's important to consider Sporothrix as another differential in endemic areas and when the presentation fits (very commonly causes cutaneous lesions in cats). 

Histoplasma is a dimorphic fungus, which means it lives in one form in the environment and then transforms into yeast once inside the animal (inhalation from the environment being the most common route of infection). 

Those yeasts then travel throughout the animal's body and can cause a variety of problems including organomegaly, skin "wounds"/masses, lymphadenomegaly, and ocular pathology. 

This kitty was started on antifungal therapy and thankfully, he did great!