Oncocytic parathyroid adenoma.

Area of Science:

• Endocrinology
• Cytopathology
• Surgical Oncology

Background:

• Fine-needle aspiration cytology (FNAC) of thyroid nodules often shows oncocytic (Hürthle) cells, necessitating histology for diagnosis.
• Oncocytic cells are also found in parathyroid glands, leading to potential diagnostic confusion.
• Hyperparathyroidism and hypercalcemia are clinical indicators of parathyroid dysfunction.

Observation:

• A patient with a history of thyroid lobectomy presented with a thyroid nodule and hyperparathyroidism.
• FNAC revealed a follicular neoplasm with oncocytic cells.
• Imaging studies showed increased uptake in the remaining thyroid lobe, leading to completion lobectomy.

Findings:

• Histological examination of the thyroid nodule confirmed a parathyroid adenoma within the residual thyroid tissue.
• Post-surgical normalization of parathyroid hormone levels and calcium confirmed the diagnosis.
• Cytomorphological similarities between parathyroid and Hürthle cell tumors can cause diagnostic challenges.

Implications:

• The study highlights the importance of considering parathyroid origin for tumors with oncocytic cells, especially in patients with hyperparathyroidism.
• Preoperative suspicion of parathyroid pathology is critical to ensure accurate diagnosis and appropriate surgical management.
• This case underscores the need for integrated diagnostic approaches combining cytology, histology, and clinical findings in thyroid and parathyroid disease.