Aeromedical evaluation and successful return to flight in a military pilot with lingual thyroid: a case report and follow-up.

Background: Lingual thyroid is a rare congenital anomaly resulting from the aberrant migration of thyroid tissue during embryonic development. Although frequently asymptomatic, its identification in military aircrew poses particular challenges given the rigorous standards of aeromedical certification.

Case presentation: A 37-year-old male military helicopter pilot was incidentally diagnosed with lingual thyroid during routine health screening. The patient remained asymptomatic throughout the clinical course. Comprehensive evaluations-including thyroid function tests, biochemical profiling, cervical magnetic resonance imaging, electronic laryngoscopy, radionuclide scanning, and portable sleep monitoring-confirmed the presence of a lingual thyroid with subclinical hypothyroidism. Imaging demonstrated the ectopic tissue at the tongue base to be the sole functioning thyroid gland. Levothyroxine therapy was initiated, resulting in normalization of thyroid hormone levels. Polysomnography was performed due to the anatomical location of the lesion and excluded obstructive sleep apnea or ventilatory compromise. Given the patient's strong motivation to resume flight duties, a multidisciplinary aeromedical evaluation was conducted. Based on clinical stability, absence of symptoms, and treatment response, the pilot was deemed aeromedically fit. Since June 2021, he has accumulated over 900 flight hours, with preserved thyroid function and no evidence of disease progression on longitudinal follow-up.

Conclusions: To the best of our knowledge, this represents the first documented case in China of a military pilot with lingual thyroid successfully certified for continued flying duties. This case suggests that congenital endocrine anomalies may be compatible with high-demand occupational roles in select cases, pending comprehensive individual evaluation and risk-based aeromedical assessment. It further supports the adoption of a risk-stratified, non-invasive management paradigm in aviation medicine, with implications for enhancing both flight safety and personnel retention.