Fang Surgical Pathology for DPM 041422.pdf

SURGICAL PATHOLOGY Yujiang FANG, MD. PhD Academic Pathologist and Associate Professor Department of Microbiology & Immunology Office: RH 262, Lab: RH 229D [email protected] Tel: (515)271-1435 Objectives 1. Define and use in proper context: o o o o o o Surgical pathology Biopsy Fixation of tissue...

SURGICAL PATHOLOGY Yujiang FANG, MD. PhD Academic Pathologist and Associate Professor Department of Microbiology & Immunology Office: RH 262, Lab: RH 229D [email protected] Tel: (515)271-1435 Objectives 1. Define and use in proper context: o o o o o o Surgical pathology Biopsy Fixation of tissue Paraffin section Frozen section Gross examination o Microscopic examination 2. Understand the two contents of the routine work associated with a surgical pathology specimen 3. Understand Four methods for specimen collection for surgical pathology 4. Grasp general rules for biopsy 5. Grasp indications for frozen section 6. Understanding advantage and disadvantage of formalin for fixation 7. Grasp Inappropriate specimens for frozen section 8. Understanding the routine procedures for paraffin section. In the clinic of the Department of Surgery, You are seeing 4 patients with your resident. These 4 patients present in the clinic because of a mass. Each patient prefers to know if the mass is a malignant tumor or not as soon as possible. Frozen section after biopsy is the quickest way to answer this question. Which of the following specimens is least possible for frozen sectioning? A. B. C. D. Single Single Single Single kidney mass prostate mass hard lymph node in the neck thyroid mass Definition n Surgical pathology is the study of tissues removed from living patients during surgery to determine diagnosis and help treatment. n n n Examine all tissues and foreign objects removed from living patients Practice of surgical pathologists Pathological diagnosis: “Gold standard in diagnosis” The routine work associated with a surgical pathology specimen includes two examinations: Gross examination Microscopic examination Gross examinations give an idea about (1) size ,shape of specimen (2) any gross abnormality like ulceration, nodularity. Gross description as well as selection of sections for microscopic study is a crucial part of pathologic examinations Specimen collection in surgical pathology n n n Incisional biopsy : for diagnosis Excisional biopsy : for diagnosis as well as treatment Tissue collection by instruments (such as needle biopsy, core biopsy, punch biopsy, endoscopic biopsy) : for diagnosis n Organs from OR: for diagnosis as well as treatment n paraffin embedding method widely used procedure). n n (the routine & frozen section (intra-operative). cytological diagnosis (exfoliative & fine needle aspiration cytology) General rules for biopsy n n n n Avoid necrosis and hemorrhage areas The larger the lesion - more numerous biopsies Ulcerated lesion including tumor –peripheral biopsy is suggested All fragments should be collected General rules for biopsy n n n n Do not crush, squeeze or do cautery Paraffin section is recommended. fix in fixatives ASAP if it is for paraffin sectioning Orientating specimen e.g. deep margin, superior and inferior margins by using sutured threads (long, short) Containers n n n Size should be corresponding to specimen volume Lid for Leak-proof Wide mouth, flat bottom Fixation of the tissue Ø Penetration rate varies a lot depending on consistency of the tissue: around 1 mm/hr Ø Compared to soft tissue, Hard tissues need more time to be thoroughly fixed. Ø 10 times volume of fixative over the specimen volume should be used. Fixatives 10% Neutral buffered formalin - fixation time 12-24 hours. Formalin (40% aqueous solution of formaldehyde) - 100ml Sodium dihydrogen orthophosphate (monohydrate) - 4g Disodium hydrogen orthophosphate (anhydrous) - 6.5g Distilled water - 900ml This fixative is suitable for most histological purposes. Other information about fixative Purpose: to preserve the tissue Other fixatives include Zenker’s solution, picric acid and Bouin’s solution. The best fixative is 10% neutral buffered formalin Advantages of Formalin Satisfactory penetration into tissue Little shrinkage Very economic Advantages of Formalin Satisfactory hardening Preserve fat & RBC well Special stains can be used on tissues after fixation. Preserve color of the tissue. Disadvantages of Formalin It need to be changed every 3-6 months. Ø Reason: In long time staying formalin, formic acid will be formed. Formic acid affects tissue stainability. Cannot preserve glycogen. Other information about Formalin Para-formaldehyde may form (white precipitate) when formalin solution is stored for long period Ø Para-formaldehyde does not affect the efficiency of formalin as a fixative Ø Para-formaldehyde can be removed by alcohol. Procedures for paraffin section n n 1. Fixation: with 10% formalin 2. Dehydration: by using gradient concentrations of alcohol (75%, 95%,100%). n 3. Clearing: by using the flammable xylene. n 4. Paraffin impregnation: fill throughout with paraffin). Procedures for paraffin section n n n 5. Embedding: to make the tissue as a block of hard paraffin 6. Sectioning: tissue is cut into very thin section (5-8 um) in thickness by using a microtome. 7. Attachment: attaching thin sections to the slides (positively charged). Procedures for paraffin section n n n 8. Dewax (Deparaffinization): dissolve paraffin by using xylene. 9. Rehydration: by using gradient concentrations of alcohol (100%, 95%, 75%). 10. Staining: H & E staining is the standard method which stain the nucleus blue (basophilic) & the cytoplasm pink-red (acidophilic). n 11. Mounting: apply mouting media (Permount) & cover slip on the slides H & E stainning : the nucleus blue (basophilic) & the cytoplasm pink-red (acidophilic) Frozen Section n n n Frozen section is not a permanent section Intraoperative consultation Fresh tissue was immediately frozen in liquid N2 and make a thin section by using cryostat Cryostat Cryostat = microtome in the freezing cabinet Indications for frozen section n n Assess if a lesion is benign or malignant Assess if there is any metastatic lymph node : such as sentinel nodes in breast carcinoma Indications for frozen section n n Assess adequacy of surgical margins Assess the presence or absence of ganglion cells in large intestinal wall of Hirschsprung disease Diagnosis of frozen section n Benign VS malignant : not specific diagnosis n In case of doubt – wait for permanent section Specimens for frozen section n n n Must be fresh tissues Small size of tissue (< 1cm) is recommended. Put in plastic bag and tightly sealed Specimens for frozen section n n n Label clearly on the bag Place the plastic bag on ice Send for examination ASAP Inappropriate specimens for frozen section n n n n Thyroid tissue (thyroid follicular lesions are difficult to be differentiated between benign and malignant) Large specimens including large tumors Highly infectious specimens : HIV TB n Question?? In the clinic of Department of Surgery, You are seeing 4 patients with your resident. These 4 patients present in the clinic because of a mass. Each patient prefers to know if the mass is a malignant tumor or not as soon as possible. Frozen section after biopsy is the quickest way to answer this question. Which of the following specimens is least possible for frozen sectioning? A. B. C. D. Single Single Single Single kidney mass prostate mass hard lymph node in the neck thyroid mass SURGICAL PATHOLOGY Yujiang FANG, MD. PhD Academic Pathologist and Associate Professor Department of Microbiology & Immunology Office: RH 262, Lab: RH 229D [email protected] Tel: (515)271-1435