Unfortunately though, without having the means to express "exterior surface", the problem remains.
If we say the tumor protrudes from the bone, then the question is, from which surface ?
Most bones have four surfaces; ventral/dorsal/medial-inner/lateral-outer. Let alone the fact, that the need to specify outer has often to do with the need to say that the tumor doesn't break through the surface of the bone facing the medullary cavity.
Then you should make your wish-list choices ventral, dorsal, medial-inner, and lateral-outer.
It may be telling that you are using specialized jargon to
describe these. We don't have a lot of specialized anatomical
words in Klingon -- we do have some -- so without being told how
Klingon anatomy describes these, we can't answer the question of
how to say it.
You might argue that you should be able to say top of the bone, front of the bone, back of the bone, and so on. And you can, in fact, say these things. But again, we're working with layman's vocabulary, not jargon.
You can proclaim that we don't have a word meaning outer surface, but you don't know that. You just know that you don't know it.
You can also complain that you don't have a word meaning outer
surface, but what are we supposed to do about it?
Anyways, I can understand that no constructed language can have words for everything. But I can't understand the need to avoid admitting that some missing words can be indeed at times necessary.
I don't do that. I'm doing my best to give alternatives and to
speculate on the general case, but all I can do is speculate.
There are some who like to force people to make their questions
conform to answers they've already decided, but not everyone here
is doing that.
As far as the interesting question "how would I describe cancer", the answer is simple:
You didn't say cancer; you said tumor. There are
multiple reasons for tumors.
I leave you with this question. What is the English singular,
third-person pronoun that refers to a person but doesn't require
you to name that person's sex? Your answer should be an
uncontroversial one. Surely there has to be a word for
that, right? Klingon has one: ghaH. Why wouldn't English
have such an obviously necessary word?
-- SuStel http://trimboli.name