A goiter is among the most common presenting symptoms of patients with thyroid diseases and is usually caused by intrinsic thyroid problems. While direct invasion of the trachea by aggressive thyroid tumors is a well-known phenomenon, the reverse situation, that is, a primary tracheal neoplasm invading by direct extension into the thyroid gland, presenting with a goiter is very rare. Here, a case of a tracheal adenoid cystic carcinoma(ACC), presenting with a diffuse goiter, is reported. A 47-year-old woman presented with slowly growing anterior neck swelling. A physical examination showed a diffuse firm goiter. The patient was euthyroiditic, and serum negative for thyroid autoantibodies. Thyroid ultrasonography and neck CT revealed a doughnut-shaped mass, encircling the trachea and displacing the thyroid anteriorly. Ultrasonography-guided fine needle aspiration(FNA) was compatible with an ACC, and a subsequent surgical resection confirmed the diagnosis. Although the occurrence of a tracheal ACC invading the thyroid is rare, this case highlights the need to be aware of unusual lesions arising in the region of the thyroid. This knowledge will help in making the correct cytological diagnosis when these lesions are sampled by FNA
BACKGROUND The introductian of highly sensitive imaging techniques has made it possible to detect many nonpalpable nodules, or incidentaloma. Because these nodules are small sized or deep seated, the diagnostic approach is difficult with conventional methods but it is easy with ultrasound-guided fine needle aspiration (FNA). However, the role of ultrasound-guided FNA on the incidentalomas has been poorly evaluated, so we tried to assess the diagnostic value of high resolution ultrasound-guided FNA in the incidentalomas. METHODS: One hundred forty-nine patients who underwent high resolution ultrasound-guide FNA for nonpalpable nodules that was smaller than 1.5 cm in diameter at Kosin Medical Center from June, 1996 to April, 1998 were included in the study. Ultrasound-guided FNA was performed with a 22-guage needle attached to 10 mL syringe with 10 MHz linear transducer in a free hand fashion. The aspirated materials were smeared and stained with Papanicolaou stain. For those who underwent surgery histopathologic diagnoses were compared to cytological diagnoses. RESULTS: The mean age of the patients was 45 and most of them were middle aged. Male to female ratio was 1:11.4. Of 149 patients 16 were involutional change, 55 hyperplasia, 42 Hashimotos thyroiditis, 8 follicular neoplasm, 19 papillary carcinoma, 1 subacute thyroiditis, and 6 inadequate specimen. Of the 149 nodules, 123 cases were solid, 11 cystic, and 15 mixed. Malignant nodules were more frequent in the solid nodule, but there was no significant difference between each group. Ten of 93 cases (10.7%) measured less than 1 cm and nine of 56 cases (16.1%) between 1.0 cm to 1,5 cm were malignant nodules. The difference of incidence rate of malignant nodules between each group was not significant. The incidence of malignancy was 13.6% (12/88) in solitary nodule and 11.5% (7/61) in multiple nodules. The difference of incidence rate of malignant nodules between each group was not significant. Eighteen cases including 14 malignancies diagnosed by FNA underwent operation. Of those 13 were papillary carcinoma and 5 adenomatous goiter. Upon the correlation of ultrasound-guided FNA cytology with pathologic diagnosis, the sensitivity of ultrasound-guided FNA cytology in differentiating benign and malignant nodule was 92.3% and overall diagnostic accuracy was 80.0%. The obtainability of adequate cytologic specimen by ultrasound-guided FNA was 95.9%. No complication except pain was noted during this study. CONCLUSION: High resolution ultrasound-guided FNA cytology may be useful for the diagnosis of thyroid cancer in the thyroid incidentalomas and also useful for early detection of recurrence of thyroid cancer .