NRAS-mutated oncocytic benign liver lesion in an organ donor: Pitfalls and troubles in frozen section diagnosis and risk assessment.

Background: In the transplant setting, the definition of the risk of neoplastic transmission from donor to recipient often requires intraoperative pathological evaluation on frozen sections. Although most lesions can be easily classified into acceptable or unacceptable risk according to the Italian National Guidelines, there are cases in which unusual histologic features cannot be further investigated because of the lack of ancillary techniques on frozen sections.

Case Presentation: Here we present a case of a liver lesion in a 51-year-old male donor, subjected to histopathological on-call examination.

Multifocal Fibrosing Thyroiditis: an Under-recognized Mimicker of Papillary Thyroid Carcinoma.

Multifocal fibrosing thyroiditis (MFT) is an enigmatic entity, characterized by multiple fibrotic scar-like lesions with a paucicellular fibrotic center surrounded by a cellular peripheral area with reactive-appearing follicular cell atypia and variable chronic inflammation. Although poorly recognized and likely underreported in surgical pathology, the entity is considered rare with only 65 cases to date-including the current one reported to expand on the preoperative findings of this under-recognized entity. The average age of the patients is 46.