Pathologists In Medical Malpractice Cases
by Gregory R. Kauffman, M.D., J.D.

Introduction

Pathology is a broad specialty of medicine which overlaps many other fields. Pathologists are responsible for making or confirming the diagnosis of cancer and other conditions based upon naked eye and microscopic examination of tissue samples removed at surgery, and cells and body fluids spread out on microscopic slides, such as with a Pap smear. Pathology malpractice often involves cancer diagnosis. Misdiagnosing a benign condition as cancer can subject a patient to debilitating surgery, radiation and chemotherapy, and the emotional trauma of a death sentence. Misdiagnosing cancer as a benign condition can result in delay in diagnosis, allowing a curable cancer to become incurable. Pathologists as expert witnesses on causation issues can dramatically affect the course of non-pathology medical malpractice and other personal injury and wrongful death cases.

The major divisions of pathology are anatomic pathology and clinical pathology. Board certification is available in both, and most pathologists in clinical practice are trained and board certified in both. Anatomic pathology mainly involves examination of tissues (surgical pathology) and cells (cytology), and the performance of autopsies on the bodies of persons dying in the hospital from conditions not believed to be the result of accident, suicide or homicide. Clinical pathology consists of performance and interpretation of laboratory tests on tissues and body fluids, such as chemical testing of blood and urine, DNA testing, blood counts, examination of spinal fluid for chemical changes, inflammatory cells and bacteria associated with meningitis, and cross-matching of blood for transfusion.

Pathology malpractice cases typically involve anatomic pathology, arising from misdiagnosis of cancer. Pathology experts in other medical malpractice cases are usually anatomic pathologists, testifying most commonly on causation issues. This articles provides background information about anatomic pathology practice and discusses deposition and cross examination of pathologists as defense experts in colon and breast cancer litigation where they are frequently employed, and as defendants in misdiagnosis cases.

The Practices Of Anatomic Pathology

With few exceptions, organs and tissue specimens removed at surgery are submitted to the laboratory for examination and diagnosis by an anatomic pathologist. The gross examination consists of a naked eye inspection and description of the specimen usually by a pathologist but sometimes by a non-physician assistant. Smaller specimens such as biopsies are usually entirely put into a "block", imbedded in paraffin from which thin slices are cut, put onto microscopic slides and treated with various stains which color different components differently to allow for microscopic examination. Representative sections are cut from organs and larger specimens and similarly processed. Tissue blocks and microscopic slides are usually kept for many years. Remaining portions of organ and large specimens are kept in preservative for a shorter time. Microscopic examination and diagnosis can often be completed in a day or two from surgery.

"Frozen Section" refers to an intraoperative pathology diagnosis where a biopsy is taken immediately to the laboratory, quickly frozen, and thin sliced and put onto slides for immediate microscopic examination and diagnosis. The frozen tissue is then processed as above for "permanent" slides. The microscopic appearance on frozen sections is not as detailed as with permanent sections and contains more artefacts so that definitive diagnosis sometimes cannot be made on frozen sections, and must be deferred to permanent slides.

Cytology includes interpretation of pap smears, fine-needle aspirates (suspensions of cells obtained from tumors, for example, using long, thin, hollow needles) and slides made from body fluids. Especially with Pap smears, initial interpretations may be made by non-physician cytotechnologists, with only abnormal slides being reviewed by a pathologist.

The Pathologist as a Defense Expert

1. Misdiagnosis of Breast Cancer

Breast cancer is not a single disease, but rather occurs in a variety of forms based upon pathologic type.^1,2,3 The most common form of breast cancer is ductal cancer, arising from the cells lining the ducts of the milk glands in the breast. The cancer cells may be confined to the ducts (intraductal) or, often at diagnosis, may have penetrated the ducts and extended into the adjacent breast tissue (infiltrating ductal cancer). Infiltrating cancers have the capacity to invade blood vessels and lymphatic channels, and thereby metastasize, or spread through different organs such as lymph nodes, lung and bone. During this author's experience, little has changed in defense of these cases.

The defense expert pathologist typically attempts to establish that the victim's prognosis did not change on account of any delay in diagnosis.^4,5 Depending upon the circumstances, the expert testifies that the cancer is unusually aggressive, or that its growth rate was such that delay made no difference.

In cases of so-called "inflammatory" cancer, a cancer which has invaded lymphatic channels in the skin causing the skin to appear inflamed and a form of breast cancer with a very poor prognosis, the pathologist will claim that the cancer was an inflammatory cancer from its inception. Some infiltrating ductal cancers, however, which start out as a curable cancer in the form of an isolated breast lump, can, if neglected long enough invade skin lymphatics and become inflammatory. Such cancers may not be a different type of cancer but rather a stage in development of cancer.^6,7

Through testimony of a pathologist, the defense may claim that a cancer is very rapidly growing and has a particularly bad prognosis, despite a long history of a palpable lump which enlarged only slowly. The pathologist may testify that microscopically, the cancer is poorly differentiated, meaning that the cells look markedly different from normal cells, which generally correlates with more aggressive behavior, or that it shows blood vessel and/or lymphatic invasion or that numerous cancer cells are in the process of dividing, appearing as "mitotic figures"^8,9, also indicating a worse prognosis. It is well-established, however, that breast cancer may remain localized and slow growing for some time, and then show accelerated growth which may be due to an increase in the degree of genetic abnormality of the cancer cells accompanied by a change in the microscopic appearance of the cells to one of lesser differentiation. If caught earlier, the cancer would likely have been better differentiated, slower growing, and less aggressive. A change in the immunologic status of the host may also allow the cancer to grow faster. Predicting the behavior of a primary cancer from a focus of spread (metastasis) may make the cancer appear more aggressive, since metastases often grow faster than the primary. Most cancer cells which break away from a primary cancer, the original cancer giving rise to metastases, probably die. Cancer cells which are able to lodge at a distant site and grow tend to be the hardier, more rapidly growing and more aggressive cells.

DNA flow cytometry is sometimes used by defense expert pathologists to suggest that a cancer was aggressive and already incurable at the time it could first have been diagnosed.^10,11 In the author's experience, this is most often done with breast cancer. DNA flow cytometry is a laboratory technique to measure the amount of DNA in cancer cells. The DNA content of normal cells is referred to as "diploid", meaning two sets of each chromosome are present. The DNA index (DI) of normal cells is 1.0. Cancer cells tend to be "aneuploid", accumulating extra sets of chromosomes as the cells become less differentiated, and to have correspondingly higher DI values. The same counter arguments as with other pathology defenses apply. DNA flow cytometry has remained a largely investigational procedure, and is not done routinely in most centers. Establish who called for the analysis, why, and what, if any, use was made of the test results other than defending a lawsuit. DNA flow cytometry is often not obtained until litigation is begun. Prognosis tables in routine clinical use do not incorporate DNA flow cytometry results in determining prognosis, nor is such testing routinely used to determine treatment.^12,13

A defense expert pathologist, surgeon or oncologist may take the position that delay in diagnosis of breast cancer, as a generality, makes no difference in survival, relying upon a number of mostly older articles published in major textbooks and peer-reviewed medical journals which appear to support this view.^14,15 As this flies in the face of common sense, and is contradictory to everything the public has heard about cancer for decades, one must question if these articles were written to advance medical knowledge, or to provide a defense for negligent doctors similar to obstetric literature stating that obstetrical negligence does not cause cerebral palsy. Breast cancer of certain pathologic types, such as medullary and lobular carcinoma in situ (cancer arising from the milk glands rather than the ducts, prior to breaking through the wall of the gland and spreading into the adjacent breast tissue) may remain localized for a long time. Other cancers such as poorly differentiated infiltrating ductal cancer may metastasize very early, and rarely, even before the primary cancer is detected. Studies reporting that delay makes no difference do not distinguish pathologic type.16 For several decades, however, studies which consider different pathologic types separately have shown that delay in diagnosis does make a difference in prognosis.^{17, 18, 19, 20}

The notion that all breast cancers metastasize before they are big enough to be palpable, like the argument that delay makes no difference, is contrary to what the American Cancer Society, the National Cancer Institute and the National Institutes of Health have told physicians and the public for decades in terms of importance of early detection of breast cancer.^{21, 22, 23} The "doubling time" defense is frequently used in cancer misdiagnosis cases, and the testifying witnesses are often pathologists. The witness chooses an average time for the patient's cancer cells to divide. Theoretically, then, the volume (not the diameter) of the cancer doubles during this time period. Counting back from the volume of the cancer at diagnosis, its volume, and its diameter can be calculated, at any previous time. The witness can pick a short doubling time from the ranges of doubling times reported in the medical literature of breast cancers, and thereby claim that the cancer was very aggressive, too small to be palpated at a time in issue, and arose suddenly later on before anything could be done about it. A longer doubling time would support a contention that at a certain time, the cancer was already so advanced that the prognosis did not change due to subsequent delay, or that metastases had been present for a long time. Paradoxically, this would suggest that a cancer whose cells take a long time to divide, ordinarily a less aggressive cancer, would have a worse prognosis. The key, of course, is that with a longer doubling time, the cancer would have remained at a curable stage for a longer time at the beginning. The reader is referred elsewhere for discussions of the many flaws of the doubling time defense.²⁴

2. Misdiagnosis of Colon Cancer

Failing to properly evaluate the complaint of rectal bleeding, despite a plethora of medical literature available to physicians and information disseminated to the public about its importance as a sign of colon cancer for decades, continues to result in many, if not the majority of the colon cancer deaths each year in the United States. The usual role of the pathologist defense expert in these cases is to testify that the cancer was already at an advanced stage and therefore incurable, or was too small to have been diagnosed, at the time of the defendant's involvement. As in the case of breast cancer, these defenses are often based on doubling times.

There is a rough correlation between the diameter of a colon cancer and its depth of invasion into the bowel wall. The depth of invasion into the bowel wall is used to determine stage, for example, in the Duke's classification system, the staging system most often used to determine prognosis.²⁵ Doubling time calculations, then, may be used to determine stage and prognosis at any previous time. Paradoxically, as with breast cancer, a long doubling time predicts a more advanced stage at a previous time. A long doubling time may also be used to support the contention that metastases had been present for a long time. A short doubling time can be used to bolster testimony that at the time the victim was bleeding and should have had a colonoscopy, he was bleeding from the hemorrhoids which the defendant diagnosed, since the cancer was too small to have been the source, and too small to have been visualized. The fallacy here is apparent from the natural history of colon cancer. Numerous studies have demonstrated that colon cancer almost always arises from a polyp which is often readily demonstrable for years provided appropriate studies are done, and which may bleed intermittently for years before an invasive and ultimately incurable cancer develops.^{26, 27}

As with breast cancer, the defense expert pathologist may testify that the cancer was highly aggressive and likely incurable at an unusually early stage, as shown by a poor degree of differentiation of the cancer cells (similarity in appearance to normal cells), numerous mitotic figures (cells in the process of dividing) or the presence of blood vessel or lymphatic invasion. None of these features, however, form the basis of any prognostic figures presently in use. Gross extent of disease, not microscopic findings, form the basis of all staging and prognostic classifications in clinical use at the present time.²⁸

Deposing a Pathologist in a Misdiagnosis Case

The deposition of both a defendant pathologist and a defense expert pathologist on microscopic diagnosis issues may pose major obstacles for the plaintiff's attorney. In this author's opinion, the most effective way to conduct a pathologist's deposition is by using a videomicroscope equipped with an electronic in-screen pointer and attached to video monitors, a screen projector and a "Snappy", or similar digital video transfer device which makes instant copies of the microscopic field being viewed through the microscope without having to videotape microscopic images projected on the screen. This setup provides an excellent visual record of what is being described under the microscope in the form of exhibits to the deposition usable at trial. Have the pathologist mark the cells or areas of these photographs which he claims demonstrate certain features while comparing the same image through the microscope. This avoids excuses later on that photographs shown to the pathologist at trial are not representative, are out of focus, etc. This method also thwarts the "I don't practice pathology by looking at photographs" excuse. The pathologist must admit that one of the ways she learned pathology is by studying photographs, major pathology texts and journals use photographs, and the pathology board examination calls for making diagnoses from photographs. All of the characteristics used to make a diagnosis such as cell size and shape, nuclear characteristics, etc., are determinable from photographs.

Allow the deponent pathologist time to view the microscopic slides at issue and become familiar with the microscope. Ask him to verify on the record that the microscope is of acceptable optimal quality, that he has had an opportunity to adjust the lighting to an optimal level adequate for viewing the slides, and that there are no technical problems which would preclude a thorough examination of the slides. Have the pathologist confirm that the procedure being used to examine the microscopic slides under the microscope at deposition is the same as the pathologist would do in practice. The pathologist should also verify that the images on the video monitor, screen and photographs are substantially the same as that seen through the microscope. Have the witness verify that the magnifications, lighting, focus and other optical qualities of the microscope being used for the deposition are adequate for purposes of actually diagnosis in a clinical setting.

There are a variety of techniques, of course, for questioning the deponent depending upon the circumstances. Needless to say, it is important that the questioning attorney has thoroughly reviewed pertinent medical literature, and discuss the issues and review the actual slides at issue with their expert pathologist beforehand. In the author's experience, it is often extremely helpful to actually mark on the slides with a permanent, very fine point marker to facilitate locating fields of interest on the slides at deposition to be inquired about at deposition. Plaintiff's pathology expert can be extremely helpful in these regards. While videotaping the pathologist at the screen, or using the electronic pointer through the video monitor, have the deponent identify, describe and state the significance of various features in the microscopic fields. Have a good videographer assist with setting up the videomicroscope and additional equipment. Using this technique, it is possible to create a powerful visual record which can lock in the opinion of the deponent and be used effectively at trial with plaintiff's expert and in cross-examination.

Standard objections to videotaping of defendants' and defense experts' depositions are outweighed by the fact that the practice of pathology is almost entirely visual. In the author's experience, there is no other way to discover the opinion of a pathologist at deposition and prepare for trial, and no other way to present important pathology evidence to the jury. As the bases for pathologist's opinions are often entirely visual, cross-examination may be ineffective without a visual record of the microscopic fields being described.

At deposition, ask the witness to demonstrate all the features relied upon to make the diagnosis, and as to each feature, establish whether or not it is diagnostic or nonspecific, and what other conditions may produce similar findings. A classic example is "inflammatory atypia", where inflammation may produce microscopic changes resembling cancer. Find out the pathologist's differential diagnosis (a list of reasonably possible diagnoses), and if and how these other diagnoses were eliminated.

Establish through the defendant and/or the defense expert that the defendant pathologist:

1. Was provided adequate information about the patient's clinical condition, the source of the specimen and the surgeon's concerns, or could have easily obtained this information;
2. had ample time and was duty-bound to have thoroughly examined the gross specimen, and, if applicable, selected the most appropriate portions of tissue to further process and examine microscopically;
3. had enough time and was duty-bound to thoroughly examine all the tissue on the microscopic slides;
4. had the opportunity and was required, if necessary, to have gone back to the tissue block for the gross specimen for more slides if indicated;
5. had the responsibility and was able to have obtained any specially stained microscopic slides which may have been necessary for final diagnosis;
6. was required and fully able to have obtained consultation, including actual review of the slides by a recognized expert in the field if there were any doubt about the diagnosis, and that such consultation could have been obtained both quickly and relatively inexpensively, and with no risk or significant inconvenience;
7. had an obligation to indicate on the report whether there was any uncertainty about the diagnosis, and if appropriate, to outline a plan for resolving the uncertainty, such as by obtaining additional tissue or other testing, including consultation with recognized authorities before acting on the diagnosis. This is particularly important in cases where the pathologist's diagnosis will prompt major surgery. In this situation, unless the diagnosis is unquestionable, consultation is indicated;
8. was obligated to have done everything reasonably possible to have avoided a misdiagnosis; and,
9. knew the likely result of the diagnosis rendered, namely that the treating physician would rely upon the diagnosis and either subject the patient to further treatment including surgery, or dismiss the patient accordingly.