Lecture 21 11/21/24 Flashcards
How does cytology compare to histopathology?
cytology:
-evaluation of individual cells
-sampling of cells spread directly on glass slide
-specimens can be collected and slides prepared in most clinics
-evaluated by clinical pathologists
histo:
-evaluation of tissue sections
-sections of formalin-fixed tissue
-tissue collected by veterinarian but processed by histo lab
-evaluated by anatomic pathologists
What are the indications for cytology?
-characterize a detected abnormality
-cancer staging
What are the pros of cytology?
-quick and easy
-relatively safe to collect
-quick results
-often less expensive
-better fine detail of individual cells and infectious agents
What are the cons of cytology?
-no tissue architecture
-only sampling a very small area
What are the pros of histopath?
-evaluation of tissue architecture
-larger area is sampled
What are the cons of histopath?
-longer turnaround time
-usually requires anesthesia and more equipment
-more expensive
-more risk of complications
-less cellular detail
What are the sampling techniques for soft tissue cytology?
fine needle techniques:
-pin cushion/stab technique
-fine needle aspirate
exfoliative:
-impression smears
Why is formalin bad for cytology?
formalin drastically alters the staining properties of cells and renders the cytology non-diagnostic
What are the steps of cytology slide evaluation?
-evaluate slide quality
-identify types of cells present, including inflammatory and non-inflammatory cells
What are the characteristics of a high quality slide?
having all of the following:
-adequate cellularity
-intact cells
-well-spread monolayer of cells
What are the causes of neutrophilic and/or macrophagic inflammation?
-bacteria
-fungus
-some parasites
-foreign body
-necrosis
-immune-mediated disease
What are the causes of eosinophilic inflammation?
-parasites
-arthropod bites/stings
-hypersensitivities
-neoplasia
What are the causes of small lymphocytes on cytology slides?
-immune stimulation
-tumor-associated lymphocytes (non-lymphoid tumors)
-small cell lymphoma
Which aspects of cells should be evaluated during cytology?
-whether the cell type is normally expected at the site
-whether the cells are cytologically atypical
-how the cells correlate to other clinical findings
What are the cytologic features of epithelial cells?
-exfoliate in clusters
-variable shape depending on type of epithelium
What are the cytologic features of mesenchymal cells?
-exfoliate individually
-spindled, fusiform, irregular to stellate shape
What are the cytologic features of round cells?
-exfoliate individually
-round cell shape
-can often diagnose with confidence on cytology
What is a non-neoplastic example of round cells on cytology?
inflammatory cells
What are examples of round cell tumors?
-lymphoma
-plasma cell tumors
-mast cell tumors
-cutaneous histiocytoma
-histiocytic sarcoma
-transmissible venereal tumor
What are the characteristics of benign vs malignant classification?
-histopath. better for determination
-takes anatomic location, other clinical information, and typical biologic behavior into account
-cytologic features are more commonly noted in malignant lesions
What are the cytologic criteria of malignancy?
-pleomorphism/anisocytosis/anisokaryosis
-macrocytosis
-multinucleation with intracellular anisokaryosis
-numerous nucleoli
-increased nuclear size
-abnormal mitotic figures
What are the characteristics of inflammation and epithelial dysplasia?
-inflammation or irritation can cause epithelial cells to appear morphologically abnormal
-difficult to distinguish from neoplasia
What are the characteristics of inflammation and reactive fibroblasts?
-fibroblasts can proliferate in response to inflammation and appear morphologically abnormal
-difficult to distinguish from neoplasia
What is important about hyperplastic epithelium?
can look similar to normal tissue or to well-differentiated epithelial neoplasia
What is important about cytologic atypia?
does not correlate to biologic behavior in all tumors
What can be done when sampling to ensure focal pathology is not missed?
-sample several different areas of a lesion
-sample more solid areas than fluid-filled areas
