September Slide Club Report

BAC Slide Club: Three Challenging Cases Put Cytology to the Test

The latest BAC Members’ Lunchtime Slide Club took place on Wednesday 30 September. Dr Ashish Chandra welcomed Dr Abhishek Dashora, Consultant Cytopathologist and Haematopathologist at King’s College Hospital, to present three challenging cases.

Case One: finding the primary

The first case involved a 45-year-old woman presenting with a right supraclavicular lump. FNA demonstrated a highly cellular, poorly differentiated carcinoma within a lymph node. Initial immunocytochemistry confirmed carcinoma. However, the usual markers failed to identify the primary site.

SOX10 proved particularly valuable. Strong nuclear positivity raised the possibility of triple-negative breast carcinoma or a salivary gland primary. Subsequent imaging identified a right breast mass. Biopsy confirmed a grade 3 invasive triple-negative breast carcinoma.

The case demonstrated how SOX10 can provide an important diagnostic clue when more conventional markers prove unhelpful.

Case Two: appearances can deceive

The second case concerned a 40-year-old man presenting with cervical lymphadenopathy. A thyroid nodule was also identified. Thyroid FNA showed clear features of papillary thyroid carcinoma.

Attention then turned to the cervical swelling. Initial appearances suggested granulomatous inflammation. The patient’s family history of tuberculosis appeared to support that interpretation.

However, several features did not fit. There was no lymph node sampling, necrosis or giant-cell population. The cellular morphology also raised the possibility of a spindle-cell lesion. A subsequent core biopsy confirmed schwannoma.

The case provided a strong reminder against allowing clinical history to override morphology. Background features can be just as important as the dominant cell population.

Case Three: a diagnostic pitfall

The final case involved an 80-year-old woman with a large pleural effusion and previous bladder cancer. Cytology showed a highly cellular sample containing large, clearly malignant cells. The differential diagnosis remained broad.

Initial immunocytochemistry could have suggested metastatic bladder carcinoma. Further investigation, however, demonstrated a plasma-cell phenotype. MUM1, CD38 and CD138 were positive, alongside kappa light-chain restriction.

The case highlighted an important diagnostic pitfall. Malignant plasma cells can show unusual morphology and immunophenotypes. They can therefore mimic carcinoma and other malignancies.

Dr Dashora also emphasised primary effusion lymphoma within the differential diagnosis of malignant effusions. Appropriate investigation, including EBER and HHV8, can therefore be crucial.

Learning through real cases

The three cases demonstrated exactly what BAC Slide Club offers members: practical cytology, challenging differentials and shared learning based on real diagnostic experience.

BAC thanks Dr Abhishek Dashora for an excellent presentation and Dr Ashish Chandra for hosting another engaging session.

The BAC Members’ Lunchtime Slide Club returns on the last Wednesday of next month.