I've searched up medical terms mainly for breasts and this is what I found:

What's been drawn before:
Macromastia(enlarged breasts)
Andromastia(breasts on men)
Polymastia(more than two breasts)
Mastipioe(breast production)
Orochio-intramastia(fictional; testicles inside breasts)
Oophorintramastia(fictional; ovaries inside breasts)
Hyperlactia(high lactation rate)
Mammopeptia(fictional; breast digestion)

Other conditions that happen in real life to draw:
Amastia(absence of breasts)

Completely new fictional ideas:
Scleromastia(hard breasts)
Chondromastia(cartaliage breasts)
Antimastia(anti-breasts, breasts that consume milk or steals mammary glands)
Mammintrasomatia(breasts inside body)
Angiomastia(Vessel breasts; breasts that are hollow)

There are still a lot more medical terms to combine for new ideas.