Ultrasound-guided laser ablation of incidental papillary thyroid microcarcinoma: a potential therapeutic approach in patients at surgical risk

Abstract

Background: Incidental papillary thyroid microcarcinoma (PTMC), a frequent clinical problem, is usually associated with a favorable outcome. During long-term follow-up, only a minority of cases show aggressive behavior with either lymph node or distant metastases. Recently, we had an opportunity to evaluate the efficacy of nonsurgical, ultrasound (US)-guided percutaneous laser ablation (PLA) for local treatment of PTMC in an otherwise inoperable patient.

Patient and methods: Neck US examination revealed an incidental, solitary, 8 × 7 × 7 mm hypoechoic nodule with microcalcifications of the right thyroid lobe. The patient suffered from decompensated liver cirrhosis, renal failure, and recent surgery followed by external beam radiation therapy for breast cancer. Cytologic diagnosis showed papillary thyroid carcinoma, but the patient declined surgery because of high risk of thyroid surgery. After local anesthesia with 2% xylocaine, PLA was performed according to the previously reported procedure with an Nd:YAG laser.

Summary: The procedure was well tolerated, without side effects, and the patient required no analgesics. US-guided fine-needle aspiration biopsy and core-needle biopsy were performed at 1 and 12 months after PLA, which demonstrated necrotic material and inflammatory cells with no viable neoplastic cell. At the 24 months US follow-up examination, the area of necrosis further decreased, demonstrating a 4 × 4 mm hypoechoic zone and a small hyperechoic area due to fibrotic changes. A fine-needle aspiration biopsy confirmed the absence of malignant cells.

Conclusions: Laser-induced thermal ablation was a safe and effective ablative treatment for a patient with PTMC confined to the thyroid gland who was at high surgical risk. This approach should be considered only in elderly patients and/or in those with comorbidities that might expose the patients to an undue high surgical risk and only after the evaluation by neck US, computed tomography, magnetic resonance imaging, or positron emission tomography/computed tomography rules out lymph-node involvement or metastatic disease.

FIG. 1.

Baseline imaging and laser treatment. (A) US scan of the thyroid gland. An 8 × 8 mm hypoechoic nodule with intranodular microcalcification is shown in the right lobe. No further lesions were present in the contralateral lobe. (B) US-guided fine-needle aspiration biopsy of the nodule shows a cytologic pattern diagnostic for papillary carcinoma, oxyphilic variant (Papanicolaou stain). (C) US-guided percutaneous laser ablation procedure. Under US guidance, two 300 μm fiberoptics are inserted through the sheath of spinal needles into the thyroid gland; (D) US image showing the hyperechoic spots due to fiberoptics tips (arrows) near the spots due to microcalcifications (arrowheads). US, ultrasound.

FIG. 2.

Follow-up after treatment. (A) A contrast-enhanced US scan of the right thyroid lobe performed at 12 months after PLA shows a broad hypoechoic and completely avascular area fully encompassing the treated lesion. (B) Core-needle biopsy of the treated area performed at 12 months after PLA shows the presence of inhomogeneous necrotic material with absence of neoplastic tissue (haematoxylin–eosin stain). (C) US scan performed at 24 months after PLA. Right thyroid lobe presents a small avascular hypoechoic area corresponding to the treated lesion (5 × 4 mm). (D) Fine-needle aspiration biopsy of the treated area performed at 24 months after PLA. Necrotic material and inflammatory cells are present, with no viable neoplastic cell (Papanicolaou stain). Few charred debris (green arrow) and fibrous tissue (blue arrow) are depicted. PLA, percutaneous laser ablation.