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BAC Members’ Lunchtime Slide Club Meeting Report

The inaugural session of the BAC Members’ Lunchtime Slide Club took place on 31 March 2025, led by Dr. Anthony Maddox (West Hertfordshire Teaching Hospitals NHS Trust). 

The event, designed as a 30-minute interactive session, featured cytology case discussions to foster collaborative learning. Participants included Dr. Ashish Chandra (Consultant Histopathologist, Guy’s and St Thomas’s NHS Foundation Trust) and Leonie Wheeldon (Royal Cornwall Hospitals NHS Trust), who presented recent diagnostic cases.

Case Presentations

Case 1: Pleomorphic Adenoma of the Salivary Gland

Presenter: Dr. Ashish Chandra

  • Clinical Context: A 2 cm nodule in the left submandibular gland.
  • Cytological Findings:
    • Triad of epithelial cells, plasmacytoid myoepithelial cells, and fibrillary stroma.
    • Fibrillary stroma distinguished from mucin/proteinaceous material.
  • Key Learning Points:
    • Differential diagnoses: Warthin tumor or cystic lesions (excluded by stromal features).
    • Milan classification: Benign (Category 2) unless atypia, necrosis, or mitoses raise suspicion of malignancy.
    • Molecular testing (PLAG1 fusion) may aid in challenging cases (e.g., adenoid cystic carcinoma vs. pleomorphic adenoma).

Case 2: Metastatic Melanoma

Presenter: Dr. Ashish Chandra

  • Clinical Context: Chest wall nodule in a patient with a history of melanoma.
  • Cytological Findings:
    • Necrotic background with plasmacytoid cells, binucleate forms, and dispersed atypical cells.
    • Rapid on-site assessment (ROSE) guided sample triage for BRAF testing.
  • Key Learning Points:
    • Utility of FNA for molecular testing (e.g., BRAF mutation analysis via destained Pap slides).
    • Importance of saline alternatives (e.g., PBS) for cell preservation.

Case 3: Pleural Effusion Suspicious for Lymphoma

Presenter: Leonie Wheeldon

  • Clinical Context: A 69-year-old male with bilateral pleural effusions and no prior lymphoma history.
  • Cytological Findings:
    • Dispersed large lymphoid cells with mitotic figures, coarse chromatin, and lymphoglandular bodies.
    • Immunocytochemistry: CD45+ (pan-lymphoid marker), negative for epithelial/mesothelial markers (P40, calretinin, TTF1).
  • Key Learning Points:
    • Differential diagnosis: High-grade lymphoma vs. poorly differentiated carcinoma.
    • Role of flow cytometry and cell block preparation for subclassification (e.g., B-cell vs. T-cell lineage).

Q&A and Discussion Highlights

  1. Sample Preservation: PBS (not saline) is critical for cell viability.
  2. Molecular Testing: Destained Pap slides or cell blocks can be used for BRAF/PLAG1 testing.
  3. Lymphoma Workup: Broad ICC panels (CD45, cytokeratin, melanoma markers) and flow cytometry are essential for effusion analysis.

Closing Remarks

Dr. Maddox emphasized the value of these sessions for sharing routine and challenging cases. The next meeting is scheduled for 30 April 2025, focusing on recent cases from clinical practice. Members are encouraged to submit cases for future discussions. Please do register!

Feedback: Participants praised the interactive format and practical insights. Suggestions included expanding topics to cervical cytology and molecular techniques.