Joe Manganiello Posts Hospital Pics From Mysterious Health Battle

Joe Manganiello is giving his followers a firsthand look at what he was dealing with during his yearslong health battle ... and the hospital pics are pretty gnarly.

The actor shared a shot sitting in his hospital room, where he's hooked up to all sorts of machines and you can see he's significantly slimmer.

Joe explained in the caption that he'd lost 60 pounds in the 2 weeks after his surgery ... and notes you can see part of his ostomy bag if you look close enough.

The next photo's a bit graphic ... showing the incisions on his abdomen after having his ostomy bag removed and his digestive tract reconnected.

If you're squeamish you might not want to look ... because you can see the bloody hole in his stomach.

The last pic is a close-up of Joe's face covered in red spots. He explains in the caption that he'd been experiencing a "multitude of skin conditions" he suffered over the course of his 7-year illness.

He wrote ... "My skin, an immune organ, was stricken with just about every condition known to man, usually in combination."