UTILIZING HISTOPATHOLOGICAL SERVICES IN CONTEMPORARY NIGERIAN MEDICAL PRACTICE

1. UTILIZING HISTOPATHOLOGICAL SERVICES IN CONTEMPORARY NIGERIAN MEDICAL PRACTICE DR. D. SABAGEH FMCPath

2. Introduction • Histopathology is a clinical diagnostic science that underpins patient care • diagnosis, staging, treatment and management of many diseases • definition of prognostic and predictive parameters in cancer for the purpose of targeted therapy • a major backbone for tumour registries • development of biobanks for translational research • a store house for fixed solid tissue specimens and clinical records (which are vital for studies of gene expression profile and biologic markers in cancers) • It broadly encompasses both autopsy pathology and surgical pathology

3. Introduction • Autopsy pathology critically examines a body after death in order to find out • the underlying disease the patient suffered from • the ultimate cause of death • Surgical pathology provides definitive ante-mortem diagnoses that facilitate • the choice of therapy for each patient • the formulation of prognosis for the disease process • the monitoring of the outcome of therapy

4. Tools of Diagnostic Histopathology • Tools used in diagnostic histopathology include • Routine (haematoxylin-eosin) stain • Histochemical stains • Immunohistochemical stains • Electron microscopy • Flow cytometry • Molecular techniques

5. Haematoxylin-Eosin • This is the most basic tool for histopathological diagnosis • it is cost effective, universally available and simple to perform • it may suffice in the majority of histological diagnoses especially with careful clinicopathologic correlations • it is invaluable in the histological typing, grading and prognostication of many neoplasms

7. Histochemical Stains • Also referred to as ‘special stains’ • They rely of the ability of various dyes to give differential (special) staining qualities to different tissue matrix or cell components and products • applications include demonstration of • organisms • connective tissue components, pigments and other extracellular deposits • cytoplasmic constituents • enzyme histochemistry • draw backs include their empirical and non-specific nature

12. Immunohistochemical stains • These involve the use of labelled antibodies directed against specific tissue antigens or constituents • positive reactions can then be visualised by a marker such as fluorescent dye, enzyme, radioactive element or colloidal gold • It is an extremely versatile technique • can be applied to formalin-fixed, paraffin-embedded tissues, cytology specimens and electron microscopy • the varieties of antibodies and tissue targets are limitless

13. Immunohistochemical stains • It remains the most widely used investigative tool in histopathology despite the development of newer techniques • Applications include • the diagnosis of specific viral, bacterial, fungal, protozoal infections • categorisation of undifferentiated malignant neoplasms • tumour prognostication

15. Electron Microscopy • It uses a powerful magnet to focus an electron beam on a piece of tissue with the deflected beams refocused onto a cathode ray tube or photographic film by magnetic lenses • this helps to provide considerably high magnification that permits the visualisation of ultrastructural features as small as 1-2nm • Its use is limited to a few diagnostic applications by its high cost of purchase and maintenance as well as the increased turn around time

17. Flow Cytometry • Disaggregated cells in fluid suspension are passed in a single line through a laser beam causing light to scatter in different directions based on the physicochemical properties of individual cells • scattered light is detected by stationary detectors that transmit the information to a computerized unit that generates data from which cellular features (size, shape, DNA content, surface molecule expression) may be generated • It is useful in tumour diagnosis

18. Molecular techniques • These techniques are used for the detection of specific nucleic acid sequences in tissues using labelled nucleic acid probes • they can be applied to routine surgical or core needle biopsies and cytology specimens • they remain the gold standard for defining specific disease entities although they are expensive and still largely research methodologies • Techniques include • in situ hybridization • fluorescent in situ hybridization • polymerase chain reaction • nucleic acid microarray technology (gene profiling)

20. Where are we in Nigeria? • In Nigeria there is an extreme shortage of pathology services which, when provided, are below acceptable standards • There is widespread unavailability of all but the most basic tools due to lack of investment in infrastructure and reagents • many histopathology laboratories do not routinely perform simple histochemical staining methods • only a few centres provide immunohistochemical services • virtually none provide electron microscopy, flow cytometry or nucleic acid microarray technology

21. Where are we in Nigeria? • Histopathology services where available are mainly restricted to the teaching hospitals and a few federal medical centres located in major cities and are not readily available or accessible to remote parts of the countries • many state government run general hospitals do not adequately use histopathological services • the vast majority of privately owned clinics and hospitals hardly have contact with histopathology services and laboratories • This is further complicated by the severe shortage of trained histopathologists

22. Where are we in Nigeria? • Ironically the few who use histopathological services do not strictly abide by the rules which assure the quality of the results obtained • Specimen handling and storage are very poor, rendering this important part of medicine rudimentary. • The quality of clinical information provided for the histopathologist if often inadequate • The integrity and quality of the specimen obtained are vital to good histopathological diagnosis

23. Specimen Handling • Containers • preferably should be of glass with screw-top lids (reusable) or plastic with leak-proof lids (disposable) • these should be clean and uncontaminated by other tissues • they should be large enough to conveniently accommodate the tissues without squeezing or distorting the shape/architecture of the tissues

25. Specimen Handling • Labelling • containers should be labelled after the tissue has been place in and not before especially in busy centres • containers and their lids should be labelled separately • at least two patient identifiers should be used • patient’s name • patient’s date of birth • hospital number • laboratory number

26. Specimen Handling • Fixation (tissue preservation) • good preservation of tissue is the single most important factor in the production of satisfactory histology slides and thus satisfactory histological diagnosis • good fixations reduces the difficulties encountered with later stages of tissue processing in the histopathological laboratory • fixation aims to • prevent tissue decomposition • preserve tissue as near to normal as possible • protect tissue against subsequent changes during processing • give tissue a texture that permits easy sectioning • render various constituents of the tissue reactive to the various stains used

27. Specimen Handling • Fixation • to ensure good fixation • tissue must be fresh and placed in fixative immediately after removal from the body • proper penetration of fixative must be ensured • no fixative will penetrate a tissue thicker than 10mm (send sample immediately to the nearest histopathology laboratory) • the right and correctly formulated fixative must be used

28. Specimen Handling • Fixatives • all fixatives are used only once • nothing in the container should prevent any part of the tissue from coming in contact with the fixative • fixative should be at least 10-20 times the volume of the specimen • 10% buffered formalin is good for all purposes (usually sold at 40% concentration) • Do not keep tissues in water, saline, ethanol etc

29. Specimen Handling • Request and documentation • full details of the patient and referring doctor are required on the request card • patient’s age must be clearly stated • the surgical operation performed including the anatomical location, site and nature as well as the anatomical side of the tissue must be specified • the clinical diagnosis suspected by the clinician must by indicated • results of other important investigations should be included e.g. endoscopy and radiological findings • any previous histopathology or cytopathology reports must be stated

31. Utilizing histopathological services • It is important to ensure tissue diagnosis on all tissue samples removed from the human body • patient education is vital • things are not always what they seem • For clinics or hospitals located in remote areas • locate and collaborate with the nearest histopathology service/laboratory with regards to logistics especially with cytology specimens • adhoc or regular pap smear outreaches can be conducted

35. Utilizing histopathological services • Government investments are needed to create the backbone on which projects for development of histopathology departments can be built • consolidation of existing resources may be the first step

36. References • Akang EEU. Recent methods and techniques in diagnostic histopathology: Impact on tropical pathology practice. Annals of Tropical Pathology. 2010; 1(1):7-16. • Awadelkarim KD, Mohamedani AA, Barberis M. Role of pathology in sub-Saharan Africa: An example from Sudan. Pathology and Laboratory Medicine International. 2010; 2:29-57. • Maynard J, El-Nageh M. Basic histopathology and anatomic pathology services for developing countries with variable resources. WHO Regional Publications, Eastern Mediterranean Series; 23. 2003. • Jackson P, Rotimi O, Onwubuya I, Ojo O. Quality assurance and control in histopathology and the challenges facing laboratory practitioners in the tropics. Annals of Tropical Pathology. 2011; 2(2): 63-70. • Ijadunola KT, Onwubuya I, Ojo O. Health care policy and pathological services in developing countries. Annals of Tropical Pathology. 2012; 3(1):5-8.