1-15 Lymph Node FNA: I Chebib MD, R Tambouret MD, D Kuebler CT

• Indications for cytology examination
• Procuring the specimen
• Test platforms/specimen processing and triage
• Report

Basic cytomorphology

Reactive Lymph Node– C95-32492

• Abundantly cellular smears with polymorphous population of lymphocytes
• Background lympho-glandular bodies
• Small round mature resting lymphocytes from the mantle zone about 12 μm in diameter (compare to RBC 7 μm diameter) with blocky chromatin and scant rim of cytoplasm;
• Polymorphous germinal center cells
• Small and large cleaved follicular center cells with twisted nuclei with inconspicuous nucleoli in the small cells and larger cleaved cells about 2x size of the small lymphocytes and with one or two small
• Scattered larger centroblasts about 2-3x larger than small lymphocytes with finely dispersed chromatin, multiple nucleoli and basophilic cytoplasm
• Phagocytic tinglible body macrophages and many epithelioid histiocytes
• Lymphoid tangles with high endothelial venules
• Follicular dendritic cells with large round pale nuclei and abundant wispy cytoplasm, often seen as 2 cells side by side like “snowmen”
• Ancillary studies are often performed from the FNA sample and include culture and flow cytometry. A preliminary evaluation of one smear will guide triage of the sample.

Granulomatous lymphadenitis – N13-4708

• Large multinucleated giant cells
• Aggregates of epithelioid histiocytes with ovoid nuclei or elongate twisted nuclei
• Fine chromatin and small nucleoli c/w granulomata, best seen on smear but also on SP
• Consistent with a granulomatous inflammation
• AFB and GMS negative

CLL/ SLL – C99-35197

• B-cell lymphoma, consistent with small lymphocytic lymphoma/CLL
• Abundant small mature appearing lymphocytes, some with nuclei
• Rare larger lymphocytes consistent with prolymphocytes
• No evidence of germinal centers
• Flow cytometry: DIFFERENTIAL COUNT (light scatter): Lymphocytes :94%

LIGHT SCATTER GATE ANALYZED: Lymphocyte T cell total: 16% B cell total 82% CD19 82% CD20 56% kappa 82% INTERPRETATION: CD19+, CD20+, CD23+, CD43+, CD5+ B cells with monotypic expression of lambda light chain. Note: This immunophenotype is consistent with chronic lymphocytic leukemia.

• Lymph node excision (S00R692): B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA

Follicle center lymphoma– MN06-3065

• Mainly small lymphocytes with round to clefted nuclei, small nucleoli and chromatin more finely dispersed than small mature lymphocytes
• Scattered lymphoid tangles c/w follicle centers.
• Flow cytometry shows the sample is composed of 89% lymphocytes with an abnormal population of CD19+, CD20+, CD43-, CD10+, CD23+, CD5- B-cells with monotypic lambda expression
• Consistent follicle center lymphoma. (Grading of follicular lymphophomas on cytology is controversial as the architectural landmarks are usually required.)
• Core biopsy (MS06-14879): FOLLICULAR LYMPHOMA,GRADE 1/3.
• NOTE: The cores comprise lymph node tissue with preserved sinuses but numerous abnormal small to medium-sized follicular structures. These are composed predominantly of small, slightly irregular lymphocytes. Centroblasts are infrequent (<5/HPF)

Diffuse Large B-cell lymphoma – C95-D22979

• Highly cellular sample with numerous discohesive large single cells
• Note the clefted, irregular nuclei, prominent nucleoli and little cytoplasm
• Large cell lymphomas will be 2-5X the size of normal lymphs
• Tingible body macrophages are present due to high turnover of the tumor cells, don’t confuse with reactive germinal centers
• Cell clustering is absent
• On the air dried sample, note the enlargement and the difference in the chromatin pattern compared to the alcohol fixed Papanicolaou stain smear
• Flow cytometry may be falsely negative because the large lymphoma cells are fragile and may not survive processing.

Small cell carcinoma– N13-5133

• Abundant necrosis, debris and numerous predominantly single relatively small malignant cells with little to no cytoplasm, dark finely granular chromatin (unlike the background lymphocytes)
• Tumor cells do not have prominent nucleoli and demonstrate nuclear molding
• Immunohistochemistry performed on the cellblock confirmed diagnosis: TTF1 +, synaptophysin and chromogranin rare + cells

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