Noninvasive follicular thyroid neoplasm with papillary-like nuclear features

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• A new entity, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), has been proposed, potentially reclassifying some papillary thyroid carcinomas (PTC).
• Limited data exists on the clinical characteristics and long-term outcomes of NIFTP.

Purpose of the Study:

• To determine the frequency, ultrasonographic features, cytological findings, and long-term evolution of NIFTP cases.
• To evaluate the clinical behavior of NIFTP in a real-world setting.

Main Methods:

• Retrospective analysis of 129 patients diagnosed with NIFTP (tumors >1 cm).
• Data collected included ultrasonographic appearance, cytology results, treatment (total thyroidectomy or lobectomy), and radioiodine use.
• Long-term follow-up assessed structural disease recurrence and thyroglobulin (Tg) and anti-thyroglobulin antibody (TgAb) levels.

Main Results:

• NIFTP constituted 15% of PTC cases larger than 1 cm.
• Low suspicion ultrasonographic findings were common (32.5%), while highly suspicious findings were rare (5%).
• Indeterminate cytology was frequent (62%), with malignant cytology being uncommon (4%).
• No structural disease recurrence was observed during a median follow-up of 72 months (range 12-146 months).
• No significant changes in Tg or TgAb levels were noted during follow-up.

Conclusions:

• NIFTP is a significant proportion of reclassified PTCs and exhibits favorable long-term outcomes.
• The study supports the reclassification of NIFTP, demonstrating a lack of recurrence and stable biochemical markers post-surgery.
• NIFTP management may involve less aggressive surgical approaches and avoidance of radioiodine therapy.