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Egyptian Board Clinical Pathology study materials
Egyptian Board Clinical Pathology study resources

Egyptian Board Clinical Pathology: Histopathology and Cytopathology

Egyptian Board Clinical Pathology · Work through your exam, one topic at a time.

All guide sections

Histopathology and Cytopathology

Histopathology and cytopathology questions test the pathway from specimen receipt to an actionable report: fixation, grossing, processing, staining, ancillary testing and synoptic reporting.

Core rules

  • Fixation uses 10% neutral buffered formalin at roughly 10 times the specimen volume for 6–48 hours depending on thickness; underfixation causes poor morphology and false-negative immunohistochemistry, while overfixation and acid decalcification damage epitopes and DNA.
  • Grossing records dimensions, weight, inked margins, sampling of the tumour–normal interface, and lymph node retrieval.
  • H&E is routine; special stains include PAS (fungi, glycogen), Ziehl–Neelsen (acid-fast bacilli), Giemsa (Helicobacter, marrow), Congo red with apple-green birefringence under polarised light (amyloid), and Perls' Prussian blue (iron).
  • Immunohistochemistry is interpreted only with a positive and negative control on the same slide; ER, PR, HER2 and Ki-67 are reported with the stated scoring system (Allred or H-score, HER2 0–3+).
  • HER2 2+ is equivocal and requires in-situ hybridisation; 3+ is positive; 0 and 1+ are negative.
  • Frozen section answers an intraoperative question such as margin status or nature of a lesion; it is not for definitive grading and is unreliable in fatty tissue and tiny specimens.
  • Cytology uses standardised systems: Bethesda for cervical (NILM, ASC-US, LSIL, HSIL, AGC, malignancy) and thyroid (categories I–VI), with adequacy criteria stated.
  • Synoptic reporting includes tumour type, grade, size, margins with distances, lymphovascular and perineural invasion, node counts and pTNM.

Worked example

A breast excision shows HER2 immunohistochemistry 2+ with complete membranous staining in more than 10% of tumour cells. This is equivocal, not positive. In-situ hybridisation is required, and the case is positive if the HER2/CEP17 ratio is at least 2.0 or the average HER2 copy number is at least 6.0 signals per cell.

Traps

  • Calling a margin clear without a measured distance.
  • Reporting HER2 2+ as positive and triggering inappropriate therapy.
  • Over-reading crush or cautery artefact in cytology as malignancy.
  • Forgetting that decalcified bone is often unsuitable for certain immunohistochemical and molecular tests.