How many letters does the top answer for “a doctor who specializes in medical diagnosis” have?

The most common answer is diagnostician (13 letters).

Crossword clue: a doctor who specializes in medical diagnosis

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

diagnostician 13 letters wn-def

a doctor who specializes in medical diagnosis

pathologist 11 letters wn-def

a doctor who specializes in medical diagnosis