Thyroid FNAC - Cytological Report

Stain

Cytological Findings

• Abundant thin (watery) colloid - pale orange-pink, wispy, "tissue-paper" or "shattered glass" cracked appearance; characteristic of watery/serous colloid on dried smears
• Thick dense colloid - a prominent, deep purple-magenta, well-demarcated blob with a smooth/folded contour ("chewing gum" appearance) visible in the upper-left quadrant

• Hypocellular smear - very few follicular epithelial cells
• Scattered small dark blue naked follicular cell nuclei (stripped of cytoplasm during smearing)
• No cohesive sheets of follicular epithelium; no microfollicles

• Large oncocytic cell / histiocyte/macrophage - prominent single large cell with abundant dense purple-magenta cytoplasm and an eccentric round nucleus; consistent with a Hurthle (oncocytic) cell or a cyst macrophage
• Scattered lymphocytes/mononuclear cells - a few in the background
• Hemosiderin pigment / granular debris - dark blue-black granular material near the bottom center, indicating prior hemorrhage or cystic change

Impression

Benign Colloid Nodule / Colloid-rich Cystic Nodule Bethesda Category II - Benign

1. Abundant thin and thick colloid
2. Hypocellularity
3. Macrophages/histiocytes (± hemosiderin) - consistent with cystic degeneration or prior hemorrhage
4. Sparse benign follicular cells / naked nuclei
5. No nuclear atypia, no papillary architecture, no psammoma bodies, no follicular crowding

Differential Considerations

Clinical Correlation Suggested

• Correlate with ultrasound (TI-RADS classification)
• If the nodule is purely cystic and colloid-rich on imaging with benign FNAC, follow-up with repeat USG in 12-24 months is standard
• No immediate surgical intervention required for Bethesda II

Thyroid FNAC - Second Set Analysis

Stains Used

• IMG_2754 (first image): Papanicolaou (Pap) stain - alcohol-fixed, pale blue-green cytoplasm, crisp nuclear detail
• IMG_2753 (second image): Romanowsky/Diff-Quik stain - air-dried, deep blue-purple nuclei, orange-pink RBC background

Cytological Findings

• Moderately to highly cellular - a significant increase compared to the previous benign colloid nodule slides
• Multiple cohesive clusters + scattered single cells and naked nuclei throughout

• Prominent hemorrhage - abundant red blood cells, suggesting a hypervascular or hemorrhagic nodule
• Thin colloid present but not dominant (unlike the previous set)
• No thick "chewing gum" colloid

• Follicular epithelial cells in cohesive flat sheets with a honeycomb/monolayer pattern
• Possible microfollicular arrangements in some clusters (seen in second image)
• No definitive papillary clusters with fibrovascular cores visible

• Nuclei are round to oval, uniform in size
• Chromatin is finely granular and evenly distributed (normochromatic)
• No nuclear grooves detected
• No intranuclear pseudoinclusions detected
• Mild crowding/overlapping within the cluster center
• Cytoplasm: scant to moderate, pale blue-green, delicate borders

• No prominent lymphocytic infiltrate (argues against Hashimoto's thyroiditis)
• No plasma cells, neutrophils, or giant cells

Diagnostic Impression

Bethesda Category III - Atypia of Undetermined Significance (AUS) OR more likely Bethesda Category II - Benign Follicular Nodule (adenomatoid nodule / hyperplastic nodule with hemorrhage)

Key Differentials

1. Adenomatoid / Hyperplastic nodule with cystic-hemorrhagic change - most likely
2. Follicular neoplasm (adenoma vs carcinoma) - cannot be excluded if microfollicles predominate on full slide review; requires surgical excision (lobectomy) to distinguish
3. Papillary thyroid carcinoma - nuclear features are absent here, making this unlikely, but nuclear grooves/inclusions are best assessed on Pap stain at high power

Recommendation

• Correlate with clinical findings and ultrasound (size, margins, microcalcifications, vascularity)
• If microfollicles are prominent on full slide review → escalate to Bethesda IV (Follicular Neoplasm) → recommend hemithyroidectomy
• If no microfollicles → Bethesda II → repeat FNA in 12-24 months or follow with USG
• The hemorrhagic background may indicate this is from a vascular nodule; repeat FNA after 2-3 months can reduce blood-related artifact

Pre-Auricular Swelling FNAC - Analysis

Stains Used

• IMG_2757 (first image): Papanicolaou (Pap) stain - alcohol-fixed
• IMG_2758 (second image): Romanowsky/Diff-Quik/MGG stain - air-dried

Cytological Findings

• Highly hemorrhagic - abundant mature RBCs in both slides
• Pale bluish-pink proteinaceous/mucoid material in the background
• No necrosis, no thick keratin flakes, no acute inflammatory exudate

• Distinct cohesive fragment of fibrillary, chondromyxoid stromal matrix - pale blue-gray, translucent, fibrillary material
• Cells are intimately embedded within this myxoid stroma - the hallmark of mixed salivary gland tumors

• Epithelial cells: arranged in cohesive flat sheets and small clusters
• Myoepithelial cells: spindle-shaped, plasmacytoid cells embedded within and "melting into" the fibromyxoid stroma
• Scattered inflammatory cells: lymphocytes, a few neutrophils, macrophages (reactive component)
• No significant nuclear atypia, no macronucleoli, no mitoses

• Nuclei: round to oval, uniform, monomorphic
• Chromatin: fine, evenly distributed (bland)
• No pleomorphism, no prominent nucleoli
• No malignant nuclear features

Diagnostic Impression

PLEOMORPHIC ADENOMA (Benign Mixed Tumor) of the Parotid Gland

Diagnostic Criteria Met

Key Points About Pleomorphic Adenoma

• Most common salivary gland neoplasm (~60-70% of all parotid tumors)
• The name "pleomorphic" refers to the tissue architecture (diverse stromal and epithelial components), NOT nuclear pleomorphism
• FNAC is the gold standard for pre-operative diagnosis
• Bethesda/Milan system for salivary gland classification: Category IV - Neoplasm, Benign
• Treatment: Superficial or total parotidectomy with facial nerve preservation
• Risk of carcinoma ex pleomorphic adenoma (~5-15%) if left untreated long-term

Differential Diagnoses Excluded

Pre-Auricular Swelling FNAC - Three Slide Analysis

Stains

• IMG_2757 (first image): Papanicolaou (Pap) stain - medium power
• IMG_2758 (second image): Romanowsky/Diff-Quik - low-medium power (same as previous set)
• IMG_2759 (third image): Romanowsky/Diff-Quik - low-power scan of entire smear

Cytological Findings - Slide by Slide

• Large, elongated, branching cohesive tissue fragment
• Classic "melting" pattern: myoepithelial cells transitioning seamlessly into fibrillary chondromyxoid matrix on the right side
• Epithelial cells in tight orderly groups at the core
• Myoepithelial cells at the periphery - spindle to plasmacytoid morphology
• Nuclei: small to medium, uniform, round-oval, monomorphic
• Chromatin: fine, bland, evenly distributed
• No atypia, no pleomorphism, no nucleoli, no mitoses

• Hemorrhagic background
• Scattered single naked myoepithelial cells
• Small clusters with plasmacytoid cells in mucoid/proteinaceous background

• Moderate to high cellularity - 6-8 large irregular branching cell clusters visible
• Abundant fibrillar chondromyxoid matrix (deep blue-purple/magenta) intimately surrounding and within cell clusters
• Highly irregular, branching, three-dimensional cluster architecture with frayed/feathered edges where cells merge into stroma
• Classic low-power pattern of Pleomorphic Adenoma

Diagnostic Impression

✅ PLEOMORPHIC ADENOMA (Benign Mixed Tumor) - Parotid Gland

Milan System for Salivary Gland Cytopathology: Category IV - Neoplasm, Benign

Classic Diagnostic Triad - All Present

Why This is Pleomorphic Adenoma and NOT Others

Clinical Management

• Imaging: MRI parotid (better soft tissue detail than CT) to define extent and relationship to facial nerve
• Surgery: Superficial parotidectomy with facial nerve identification and preservation
• Do NOT perform enucleation alone (high recurrence risk ~25%)
• Long-term follow-up: ~5-15% risk of malignant transformation (carcinoma ex PA) if untreated for >10-15 years