In some situations, you may code without the pathology. In others, you must wait for pathology to accurately code.
When coding profee (physician), your payment is based on CPT codes, not the ICD10 codes. If the pathology would potentially change the CPT, then you should definitely wait for pathology.
I do know some practices wait for pathology on almost everything, but I do it only if it potentially changes the CPT.
Prime example is skin lesion removals. Benign vs malignant. Is it maybe a skin tag? Entirely different codes. In my specialty, for laparoscopic hysterectomies, there are different codes based on the weight of the uterus. So if the uterus is mentioned as enlarged in any way, I wait for pathology as it might change the CPT and payment.
Regarding "code based on the doctor's impression at the time of removal." Remember you cannot code suspected, likely, consistent with, rule out, etc. when coding profee. Until you have a definitive diagnosis, you code signs and symptoms. Inpatient facility rules differ.
The guideline stating to code only a definitive diagnosis or sign/symptoms in absence of a definitive diagnosis is in your ICD10 book. Check Section 1.B.4 and 1.B.18. It's also in various CMS documents.