Pathology review services exist internationally (e.g. independent second opinions on biopsy / pathology results). 
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Some diagnostic centers or labs have panels of specialist consultants for imaging / radiology / histopathology to review difficult or unclear cases. Usually this is part of their internal quality assurance or second-opinion practice.

Teleradiology / telepathology platforms (sending data / images to remote experts) are also used in some places for specialist consultations.