The Collaborative International Dictionary of English v.0.48:

pathologist \pa*thol"o*gist\, n. [Cf. F. pathologiste.]
   One skilled in pathology; an investigator in pathology; as,
   the pathologist of a hospital, whose duty it is to determine
   the causes of the diseases.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pathologist
    n 1: a doctor who specializes in medical diagnosis [syn:
         diagnostician, pathologist]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "pathologist":
   anesthesiologist, cardiologist, chiropodist, dermatologist,
   eye doctor, eye-ear-nose-throat specialist, geriatrician,
   gerontologist, gynecologist, immunologist, internist, neurologist,
   obstetrician, oculist, ophthalmologist, orthopedist,
   otolaryngologist, otologist, pediatrician, pediatrist, podiatrist,
   psychiatrist, radiologist, serologist, skin man, specialist