Thyroid function tests were within normal limits:

• TSH: 1.41 uIU/mL

• Free T4: 14.9 pmol/L

Inflammatory markers were significantly elevated:

• Erythrocyte Sedimentation Rate (ESR): 40 mm/hr

• C-reactive Protein (CRP): 55.9 mg/L

Other relevant labs:

• Parathyroid Hormone (PTH): 69.4 pg/mL (normal to mildly elevated range)

These findings raised concern for an inflammatory or hemorrhagic process involving the thyroid.

Ultrasound of the Thyroid:

• Right lobe: 47 × 18 × 16 mm, normal in size, with a few small TR2 nodules (largest 7 × 6 × 4 mm).

• Isthmus: ~3 mm, no focal lesions.

• Left lobe: 45 × 37 × 32 mm, significantly enlarged with inhomogeneous echotexture.

Notable findings:

• A well-defined, regular-surfaced, mixed (predominantly cystic) nodule measuring 37 × 30 × 27 mm occupying most of the left lobe.

• TR2 classification with no microcalcifications, no macrocalcifications, and increased perinodular vascularity.

• A small (approx. 4 mm thick), ill-defined hypoechoic lesion noted in the lower third of the left lobe, suspicious for surrounding hematoma.

Ultrasound impression: Large hemorrhagic cyst in a benign-appearing nodule; low suspicion for malignancy but correlation with clinical course and histology recommended.

Final histological analysis revealed:

• Hyperplastic thyroid follicular nodule with cystic degeneration.

• No features of malignancy.

• Hemorrhagic and degenerative changes consistent with the imaging and clinical picture.

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