I can hear the scream :)

[I am new to this comment section]
 
Masaki Kurosaki, a pure blood Quincy, was infected with hollow essence, by Shiro, a hollow that was made out of soul reapers. -> Quinces don’t have a resistance against hollow powers so instead of hollowfying, the soul suicide will happen -> Isshin Shiba bound his soul reaper powers and soul to Masaki so she doesn’t die. -> They made Ichigo -> Quincy Powers from mother, Hollow powers from Shiro and Soul Reaper powers and Engetsu fron father are all passed down to Ichigo.
 
I don’t what to call Ichigo.
 
Now, Hollow Ichigo is Zangetsu, his soul reaper powers, which include hollow powers. Tensa Zangetsu actually looks like Ichigos Vasto Lorde form.  
So i guess that form is his Bankai manifested. It would be possible, since hollow spirits are active spirits, and not passive like Zanpakutos.

@Background Pony  
Shhhh, Derpibooru is one of the keystones of The Plan(TM)! He can see every pone we poni, man!

@TheAbridgenator  
Well, “officially” it was just a test/ prototype arrancar or something, but most likely it was somehow passed on to Ichigo through Masaki, and then became what we know as Hollow Ichigo.  
Just as Aizen planned. That motherfucker.

Shit, man, if two horns could do that much damage, imagine what a whole set of antlers could accomplish! :D
 
…Did they ever give an explanation on what exactly this was? I have my own theory - that it’s actually Hollow Ichigo fully manifested as a Vasto Lorde - but tis me.