Cytologic, flow cytometry, and molecular assessment of lymphoid infiltrate in fine-needle cytology samples of Hashimoto thyroiditis.
BACKGROUND
The thyroidal lymphoid infiltrate (TLI) in Hashimoto thyroiditis (HT) represents the substrate from which thyroid lymphoma may arise. The objective of the current study was to classify the TLI in HT by comparing the cytologic features with flow cytometry (FC) data and evaluating the kappa/lambda light chain ratio and its molecular assessment.


METHODS
Fine-needle aspiration cytology (FNAC) was performed in 34 patients with HT with nodular or diffuse palpable enlargement of the gland. Two or 3 passes were performed to prepare traditional smears, FC, and immunophenotyping, and RNAlater suspensions for molecular assessment. FC was performed using the following antibodies: CD3, CD5, CD4, CD8, CD10, CD19, and kappa and lambda light chains. In 4 cases, high molecular weight DNA was extracted and used for polymerase chain reaction (PCR) to amplify the variable diversity joining region of the heavy chain immunoglobulin (Ig) genes (IgH). Statistical analysis was performed to evaluate possible associations between clinical ultrasound presentation, cytologic pattern, and TLI phenotype. Light chain expression was evaluated as the percentage of the expressing cells (</=20% and >20%) and as the kappa/lambda ratio.


RESULTS
Smears were classified as "lymphocytic," "lymph node-like," or "mixed." FC demonstrated T cells (CD3 positive [+], CD5+) in all cases, and T cells and B cell (CD19+, CD10+/-) lymphocytes in 22 cases. Light chains were expressed in 30 cases (in <20% of the gated cells in 13 cases and in >20% of the gated cells in 17 cases). Five cases demonstrated small kappa/lambda ratio imbalances and PCR analysis demonstrated diffuse bands in the gel and Gaussian curves at the heteroduplex. Statistical analysis indicated significant associations between the "lymphocytic" pattern and T-cell phenotype and between the "lymph node-like" pattern and B-cell phenotype. A significant association also was observed between light chain restriction and low light chain expression (P < .005).


CONCLUSIONS
The cytologic pattern of TLI in HT is quite representative of the clinical presentation and phenotypic cell type. Small light chain imbalances are not sustained by heavy chain Ig gene (IgH) rearrangements. FNA coupled with FC may contribute to making the distinction between florid TLI and non-Hodgkin lymphoma.
Zeppa
Pio
P
Department of Pathology, University of Naples "Federico II," Naples, Italy. zeppa@unina.it
Cozzolino
Immacolata
I
Peluso
Anna Lucia
AL
Troncone
Giancarlo
G
Lucariello
Antonio
A
Picardi
Marco
M
Carella
Carlo
C
Pane
Fabrizio
F
Vetrani
Antonio
A
Palombini
Lucio
L
D000328:Adult; D000368:Aged; D018941:Antigens, CD19 / Q000032:analysis; D044963:Biopsy, Fine-Needle; D017252:CD3 Complex / Q000032:analysis; D018956:CD5 Antigens / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D050031:Hashimoto Disease / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016130:Immunophenotyping / Q000379:methods; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D015260:Neprilysin / Q000032:analysis; D016133:Polymerase Chain Reaction; D013961:Thyroid Gland / Q000276:immunology / Q000378:metabolism / Q000473:pathology*
D018941:Antigens, CD19; D017252:CD3 Complex; D018956:CD5 Antigens; D007143:Immunoglobulin Heavy Chains; D015260:Neprilysin