Dahlin returned to Rochester in November 1945, intending to begin residency training in
general surgery. However, because of scheduling issues, he was assigned first to the
surgical pathology laboratory at St. Mary's Hospital, under the tutelage of Dr. Malcolm Dockerty. He was then appointed to the staff of the Mayo Clinic as a consultant in pathology. Rapidly, Dahlin became a skilled general surgical pathologist in the mold of Dockerty, but began to develop special expertise in neoplasms of the skeletal system. No one had previously studied such lesions systematically at the Mayo Clinic; indeed worldwide knowledge on that topic was then quite limited. Working with Mark Coventry, an
orthopedic oncologist, Dahlin cataloged the clinical, radiographic, macroscopic, and histopathologic features of virtually all bone tumors in the Mayo archive. That undertaking eventuated in the publication of a book entitled "
Bone Tumors: General Aspects and an Analysis of 2276 Cases," in 1957. That text has subsequently gone through 5 additional editions and is still in print under the editorship of Krishnan K. Unni and Carrie Inwards. ==Later career and honors==