We have reached a new milestone with the establishment of in house histopathology services.
- Refers to the microscopic examination of tissue in order to study the manifestation of disease
- Cancer management entails a multidisciplinary approach involving specialists from several different fields
- The histopathologist establishes a definitive cancer diagnosis and provides the clinical colleagues with information they require to deliver optimized care
- Histopathology reports today give detailed information and the diagnosis includes immunohistochemistry and even molecular findings
Types of samples received include:
- Incisional biopsy – diagnostic biopsies from any site
- Excisional biopsy – Small Tumors
- Punch biopsy – e.g: Oral Cavity, GIT etc.
- Core needle biopsy – e.g: Breast
- Curettage biopsy – e.g: Endometrium
- Radical excision specimens – eg. Mastectomy, Neck Dissections, Colectomy etc
- Refers to the detailed description of the surgical specimen by the histopathologist where weight, size measurements and gross descriptions are given.
- If it is a resection specimen inking of margins is done.
They deal with the preparation of tissue for microscopic examination after grossing of the specimen. These processes are:
- Immunohistochemistry has become a useful tool in surgical pathology not only for diagnoses but also for prognostication and therapy of certain tumors.
- Examples: Her2 for breast cancer, CD 117 for GIST, MIB1 for neuroendocrine tumor and CD markers for lymphomas.
Cytology Services at our centre
- This is one of the easiest screening tests available for detecting cervical cancer / precancerous conditions
- Inadequate specimens are responsible for most of the false negative diagnoses
Liquid based cytology
- Liquid based cytology like SurePath offer improved means of sampling the cervix and added advantage of HPV sampling with the same specimen.
- Fine Needle Aspiration Cytology (FNAC) and Fine Needle Non Aspiration Cytology (FNNAC) are simple outpatient procedures where a fine needle is inserted into the palpable lump and the material obtained is smeared onto glass slides, stained with Papanicolaou and MGG stain and cells are evaluated under the microscope
- The procedure does not require anesthesia and is psychologically more acceptable than a biopsy
- This rapid preoperative procedure allows cancer to be confirmed or more often excluded in patients who are worried about a ‘lump’
- Material can be collected for microbiological studies like culture / PCR in suspected cases of tuberculosis
- FNNAC sampling displays more cellular material, less cellular trauma and more importantly less likelihood of obscuring by blood. Also it has better patient compliance
- Examination of body fluids, washings, lavages, urine cytology, CSF cytology
- The above mentioned samples are processed in a specialized centrifuge called Cyto-centrifuge (Cytospin4)
- Cytospin enables a thin monolayer preparation from any liquid media
Cell block technique
- Cell block refers to examination of sediment, blood clots or grossly visible flecks of tissue from cytology specimen that are processed by paraffin embedding and staining with H & E
- Cell blocks are complementary to smears and allow extra slides to be cut for ancillary studies
Some general rules for Biopsy procedures, Fixation, Transportation of samples for Histopathology and Cytology
- All the biopsy and surgical samples should be fixed in 10% buffered formalin. Good fixation is a key factor in production of satisfactory results in histopathology and IHC. Fixation is done at room temperature. The amount of formalin should be approximately 10-20 times the volume of the specimen.
- Specimen should be transported in plastic, metal container or in a plastic bag in 10% formalin. If formalin is not available, place specimen in refrigerator at 4 degrees to slow down autolysis. Container should have an opening large enough to remove the tissue easily after it has hardened by fixation.
- Fresh unfixed tissue material is required for a) Microbiological Sampling & b) Chromosome analysis (karyotyping)
- Testicular biopsies should be sent in Bouin’s fluid
- Endoscopic biopsies from different sites and prostate core biopsies should be labeled properly
- Resection specimens of tumors and breast conservation lumpectomies should be labeled with sutures for margin orientation. This is very important as assessment of surgical margins has therapeutic implications
- Conventional PAP smears have to be fixed immediately (WET FIXED). Slightest delay will cause air drying and result in poor staining of cells with Papanicolaou technique rendering smear unsatisfactory or less than optimal for cytologic evaluation
- Samples for liquid based cytology (LBC) have to be collected in the specific fixative provided by the lab
- If smears for cytology are fixed with cytospray/cytofixative they should be allowed to dry before packing them as the cells tend to stick to paper/cardboard
- If FNAC is performed by imaging specialist or surgeon, the site, side and nature of fixation should be mentioned along with the provision of imaging findings
- When several fragments of tissue are obtained in a biopsy then the entire tissue has to be submitted to the laboratory for histological examination
- All fluid samples for cytology must be refrigerated if there is a delay in sending the sample to the lab