http://hl7.org/fhir/StructureDefinition/bodySite|5.2.0

Record details about the anatomical location of a specimen or body part. This resource may be used when a coded concept does not provide the necessary detail needed for the use case.
typedestination
baseDefinitionhttp://hl7.org/fhir/StructureDefinition/Extension
typehttp://hl7.org/fhir/StructureDefinition/Extension
Extension.value[x].typehttp://hl7.org/fhir/StructureDefinition/Reference
Extension.value[x].targetProfilehttp://hl7.org/fhir/StructureDefinition/BodyStructure