With "recurrent Nevus phenomenon" could a previously benign mole now appear dysplastic if pathologist not aware of previous biopsy or laser ablation?

Yes. Hx is important. When a benign nevus grows back after biopsy, and is re-biopsied or excised, it may now show features that closely mimic a dysplastic nevus or even melanoma under the microscope. This melanoma-like pattern is called "recurrent nevus phenomenon." A pathologist might accidentally misdiagnose a benign, recurrent nevus as a DN or melanoma, if they don't know (or suspect) it was previously treated.

Related Questions

Can a recurrent Nevus be misdiagnosed as melanoma or dysplastic if the pathologist is not aware of previous biopsy or laser ablation?

Incompletely removed. A nevus is a benign skin growth (mole or beauty mark) that may be of concern if it has a changing or irregular appearance. A biopsy can be performed to determine if there are abnormal cells that would prompt removal. If not removed completely, it can recur. Further removal is then indicated if the cells were abnormal. It can be difficult to interpret pigmented cells, a challenge for pathologists. Read more...
False DX of melanoma. When a benign or dysplastic nevus grows back after biopsy, and is re-biopsied or excised, it may now show features that closely mimic a melanoma under the microscope. This melanoma-like pattern is called "recurrent nevus phenomenon." A pathologist might accidentally misdiagnose a benign, recurrent nevus as melanoma, if they don't know (or don't suspect) it was previously biopsied. Read more...