Cytomorphology

Cytomorphology

1. Classical features

   • Cytoplasm
     • Generally provides an indication of origin, functional state & degree of differentiation
     • Variation in size & shape of similar cells (Anisocytosis). Abnormal cells can have larger or smaller cyto vol. Nuclear : cyto ratio affected. Ultrastructural composition of the cyto exerts a major influence on staining reactions (mitochondria, golgi, lipid, carbs, & hormones, etc.)
     • Abnormal features
       • Keratinization - squamous differentation. Cyto moulding. Cell engulfment. Degenerative changes - swelling, vacuolation, loss of integrity of plasma membrane (cytolysis).
   • Nucleus
     • reflects state of proliferation & stage in cell cycle
     • Normal mature nucleus
       • Relatively small compared to overall vol of cell. Round or ovoid. Smooth nuclear contour. Even distributed. Finely granular homogeneous chromatin. Little variation between cells of similar type.
   • Nuclear : Cytoplasmic Ratio
     • In 2D cytoprep - nuclear size is proportional to the relative nuclear area. Poorly differentiated cells usually possess enlarged nuclei for the same cytoplasmic vol. Therefore an elevated nucelear:cytoplasmic ratio.

2. Criteria for cytology diagnosis

   • Final diag depends on...
     • Detailed site specific knowledge
     • Experience of normality
     • Awareness of mimics & artefacts & limitations of the technique
       • Post-radiotherapy, chemo & viral changes, etc. may mimic neoplasia
     • Detailed clinical information
   • Specimen Cellularity
     • number & type of cells present give important info about target tissue
   • Increased Cell Numbers (hyperplasia)
     • physiological (breast enlargement) or pathological (prostate enlargement)
   • Decreased cell Numbers (hypoplasia)
     • Physiological (due to atrophy, apoptosis, senescence or degeneration) or Pathological (hypoplastic left heart syndrome
   • Discriminate between non-neoplastic, pre-neoplastic, & neoplastic
   • Cyto-nuclear differences between low grade neoplasia & regenerative or hyperplastic cells may be subtle

3. important features

   • Cellularity
   • Architectural pattern
   • Nuclear & cytoplasmic
     • features
     • artefacts

4. Gynaecological Cytopathology

   • Abnormal Nuclear Features
     • Dyskaryosis - abnormalities of nuclear morphology
       • Graded: Mild (CIN I), Moderate (CIN II), Severe (CIN III)
     • Increased nuclear DNA content
       • Dense nuclear staining (hyperchromasia). Irregular, coarse & clumped chromatin. Thickened nuclear envelope (karyotheca). Variation in size & shape of nuclei between cells ( anisokaryosis / anisonucleosis). Nuclear membrane becomes irregular, with grooving indentation or crenation. Multinucleation also observed.
   • Nucleoli
     • Normal nuclei contain small, discrete nucleoli composed of RNA & proteins. Both multinucleolation & macronucleoli are observed in proliferative states - both neoplastic & non-neoplastic.
       • Degenerative chromatin may appear as dense, contacted mass, dense fragments, undergo dissolution.