this spoils the answer, but also colloquially we would not pluralize this. e.g. “bilateral renal cell carcinoma”. bilateral primary tumors are quite rare which is probably why but i favor rejection
I disagree, and I don’t see how it spoils the answer (I think your referring to c2?). When filling in the blank for “…will typically develop ____ retinoblastomas”, both “unilateral” and “bilateral” are equally valid grammatically (i.e., “…will typically develop unilateral retinoblastomas” is a perfectly valid (however incorrect) response).
Rather, saying that patients “will typically develop a bilateral retinoblastoma” is grammatically weird. To your point, we don’t say patients develop “a” bilateral RCC.
At the very least, I think it make sense to remove “a(n)”. The pluralization of retinoblastoma, I’m less tied to, but still stand by.
Your example of RCC is generally an exception to the rule. Typically, we pluralize disease entities when they occur in separate anatomic structures, even if they’re of the same type—e.g., “bilateral cataracts” not “bilateral cataract”; “bilateral meningiomas”; “bilateral hemangiomas”; “bilateral vestibular schwannomas”; “bilateral pulmonary emboli.” The reasoning is that each side harbors a distinct lesion or neoplasm, rather than a single bilateral disease process.
By contrast, certain cancers like RCC are often treated as a single disease entity that can involve one or both organs, so the singular tends to persist (“bilateral RCC”). In my understading, retinoblastoma behaves more like those in the first group—it arises independently in each eye, not as one bilateral tumor, so to speak