Introduction
Forensic histopathology is the application of histological techniques and examination to forensic pathology practice. It is a unique and specialised aspect of pathology practice. Compared to clinical histopathology practice, in which similar techniques are applied, there are several notable differences:
- The nature of specimens varies significantly between forensic pathology practice and clinical histopathology practice. Clinical histopathology typically involves specimens and biopsies that consist of portions, fragments, or sections of diverse organs. Diagnoses are derived from histological sections of tissues, obtained through deliberate sampling of the specimens, usually after proper fixation. On the other hand, forensic pathologists routinely assess complete organs, initially examining them without fixation. These organs frequently exhibit varying degrees of autolysis and putrefaction. This distinction leads to a fundamentally different approach in the initiation of histological sampling and examination.
- The spectrum of organ and tissue examination varies between clinical histopathology practice and forensic pathology practice. In histopathology, small biopsies from areas like the breasts, aerodigestive tract, and female genital tract are common. Biopsies of major organs like the heart, lungs, liver, brain, and kidneys often require specialized expertise. On the other hand, forensic pathologists regularly study entire hearts, lungs, livers, brains, and kidneys, though with a slightly different focus. Although they also examine breasts, intestines, and lymph nodes, these receive less attention compared to the major organs that are more relevant to the cause of death. Recognizing visible issues in organs without preservation is crucial in forensic pathology. Nonetheless, forensic pathologists need to identify issues in all organs, conduct thorough examinations, and create accurate reports.
- Histological examination of surgical and clinical specimens focuses on diagnosing and predicting outcomes. Ensuring clear margins around tumor growth is crucial for planning future care. Accurate grading and classification of tumors also play a key role in treatment and prognosis. In contrast, forensic postmortem examinations primarily aim to determine the cause of death. Sometimes, the cause of death is evident through visual inspection without needing histological analysis. In such cases, other factors like unrelated health issues are less important.
The Roles of Histology in Forensic Pathology Practice
The major roles of histology in forensic practice are as follows:
- To establish the cause of death
- To confirm and refine macroscopic diagnosis of macroscopic pathological lesions
- To confirm or refute antemortem diagnosis and clinical suspicions
- To evaluate medical and surgical interventions as a means of medical audit
- As a form of permanent documentation of pathologies identified at autopsy
- As an essential source of material for medical undergraduate and postgraduate teaching
- As a source of research
Procedures Involved in Forensic Histopathology
Forensic histology involves the examination of tissue samples obtained during autopsies to determine the cause and manner of death. The procedure typically follows a series of steps to process and analyze the samples. An overview of the procedure involved in forensic histopathology:
- Tissue Collection/Grossing: During the autopsy, the forensic pathologist or medical officer collects tissue samples from various organs and body parts. These samples are carefully chosen based on the circumstances surrounding the death and the initial examination findings.
- Fixation: The collected tissue samples need to be preserved to prevent decomposition and maintain their structural integrity. Fixation involves immersing the tissue in a 10% buffered formalin solution with the ratio of 1:10 v/v for a minimum of 3 days. Formalin helps prevent degradation and stabilizes the tissues for further processing.
- Processing: After fixation, the tissue samples undergo a process of dehydration using alcohol, clearing using xylene, and embedding in paraffin wax. This process prepares the tissue for sectioning and staining.
- Sectioning: The paraffin-embedded tissue blocks are cut into thin sections using a microtome. These sections are typically around 3 to 5 µm thick. The sections are mounted on glass slides for further processing. The tissue blocks will be kept for 20 years.
- Staining: Different staining techniques are used to highlight specific features of the tissues. Hematoxylin and eosin (H&E) staining is commonly used, as it highlights cell nuclei (hematoxylin) and cytoplasm (eosin), providing valuable information about tissue structure and abnormalities. Special stains and immunohistochemistry will be requested if further test is needed.
- Microscopic Examination: The stained tissue sections are observed under a microscope. Forensic pathologists and medical officer examine the tissue for any abnormal cellular structures, signs of trauma, disease, or other relevant findings.
- Documentation: Detailed records and observations are made during the microscopic examination. This includes noting any injuries, abnormalities, and conditions present in the tissue samples.
- Photography: Photographs may be taken using a microscope-mounted camera to document significant findings. These photographs can serve as visual evidence and be included in forensic reports.
- Interpretation: The observed histological features are interpreted in the context of the individual’s medical history, circumstances of death, and other autopsy findings. The forensic pathologist or medical officer determines whether the histological findings contribute to the cause and manner of death.
- Reporting: The results of the histological examination are documented in a comprehensive report. This report includes descriptions of the observed tissue abnormalities, their significance, and how they relate to the cause of death.
- Collaboration: In some cases, forensic histopathologists may collaborate with other forensic experts, such as toxicologists or odontologists, to gather a complete understanding of the circumstances surrounding the death.
- Legal Proceedings: The histopathological findings and report may be used as evidence in legal proceedings, such as criminal investigations, insurance claims or court cases.
References
- Lau, G., & Lai, S. H. (2008). Forensic histopathology. Forensic pathology reviews, 239-265.
- Dettmeyer, R. B. (2018). Forensic histopathology: fundamentals and perspectives. Springer.
| Last Reviewed | : | February 2024 |
| Writer | : | Ismadi b. Ismail |
| Translator | : | Muhd. Yazid b. Suhaimi |
| Reviewer | : | Nurhusni binti Mohammad Room |
