misdiagnose
From Longman Dictionary of Contemporary Englishmisdiagnosemis‧di‧ag‧nose /ˌmɪsdaɪəɡˈnəʊz $ -ˈnoʊs/ verb [transitive] FIND OUT#to give an incorrect explanation of an illness, a problem in a machine etcmisdiagnose something as something Her condition was misdiagnosed as arthritis.→ See Verb tableExamples from the Corpusmisdiagnose• Roy's heart condition was originally misdiagnosed as pneumonia.