The Pathologic Diagnosis as an Argument

By: AMFS Board Certified Clinical Pathologist 

The pathologist daily engages in deductive arguments in which the truths of conclusions (diagnoses) are the logical consequences of their premises. In medical-legal cases meticulous examination of the premises will establish the truth/untruth of the diagnosis and the place to start is the pathology report and the medical record.

The pathology report is an extremely complex document and at a minimum contains the following premises/assumptions:

1. Detailed laboratory identifying information
2. Patient’s identifying information
3. Clinical history
4. Gross/macroscopic description
5. Microscopic description (interpretation of slide morphology)
6. Intraoperative consultation
7. Diagnosis
8. Comments
9. Amended reports
10. Internal consultation
11. Additional studies (special stains, immunohistochemical stains, molecular pathology studies, flow cytometric studies, cytogenetic analysis, electron microscopy, immunofluorescence, etc.)
12. Outside (expert) consultations
13. Quality assurance procedures — especially communications

As each case is evaluated the pathologist continually examines these premises/assumptions to ensure the evidence supports the factual correctness.

If in a medical-legal case, the truth of a pathologic diagnosis is in question, early consultation with a qualified expert pathologist will help greatly in examining this issue. Pathologists think differently than lawyers and most other physicians and are uniquely trained to evaluate the question of diagnostic truth. The following are a few examples of diagnostic errors found by determining certain premises/assumptions were incorrect.

Assumption that the tissue present on the H&E-stained slide was that of the patient. A discrepancy was noted during the comparison of the description of the tissue submitted for microscopic examination and the appearance on the H&E-stained slide. DNA testing confirmed a mismatch and investigation revealed that the slide had been mislabeled during processing. The patient had unnecessary surgery.

Assumption that all pertinent diagnostic features present on the H&E-stained slides were seen by the examining pathologist. An appendix was diagnosed as showing acute appendicitis. Subtle features of an uncommon mucinous adenocarcinoma were overlooked and the diagnosis and treatment of malignancy were delayed.

Assumption that the pathologist is qualified by training and experience to reach a diagnosis in certain cases and to recognize when to request expert consultation. An atypical proliferative soft tissue lesion was diagnosed as a rare type of sarcoma, rarely seen by any pathologist. Upon review inconsistencies were noted in clinical presentation, imaging studies and interpretation of histologic features. When the case was reviewed by a multidisciplinary team with considerable soft tissue experience, they easily reclassified the lesion as benign. The patient had received several cycles of chemotherapy and was scheduled for radical surgery.

Assumption that everything that looks malignant is malignant. A needle biopsy of a lung mass in a smoker was diagnosed as malignant. An excisional biopsy showed the presence of tuberculosis with marked reactive atypia. The medical literature clearly documents that false positive diagnoses of malignancy in cases of tuberculosis can occur due to the marked atypia induced by the infection. Excisional biopsy is required to resolve this issue and therefore no harm was done to the patient.

The pathologist is uniquely qualified to examine pathology reports (and medical records) regarding correctness of premises/assumptions. Get them involved early to evaluate the facts and formulate appropriate questions to focus your efforts. Consulting a qualified pathologist prior to deposing an opposing pathologist will ensure you ask the right questions.