Ultrasonographic and non-enhanced CT features of acute transient thyroid swelling following fine-needle aspiration biopsy: report of four cases

Abstract

We report four cases of acute transient thyroid swelling following fine-needle aspiration biopsy, a rare complication of still unknown origin. The ultrasonographic pattern was fairly similar to that in previous reports: swelling of the thyroid with a patchy and heterogeneous appearance and diffusely scattered hypoechoic "cracks" that showed no blood flow signals with color Doppler ultrasound. There were also some features that differed from those in previous reports. Though thyroid swelling is typically diffuse and bilateral, it was unilateral or asymmetrical in some of our cases. While thyroid swelling is said to resolve spontaneously within 1-20 h, abnormal ultrasonographic findings persisted for more than 48 h in one case. Unlike previous reports, we have experienced cases with ultrasonographic findings of concomitant minor subcapsular hematomas. In one case, CT demonstrated not only thyroid swelling but also abnormal attenuation in perithyroid tissue extending to the retro-hypopharyngeal space and to the paraesophageal mediastinum. Although vasodilatation and diffuse vascular leakage are speculated to be the underlying mechanisms, our ultrasonograms at the time of the complication failed to demonstrate enlarged intrathyroidal vessels or hypervascularity with color Doppler ultrasound. More awareness and a description of the cases may help to clarify the pathogenesis of this self-limited complication.

Acute and Transient Thyroid Swelling Following Fine-Needle Aspiration Biopsy: Its Prevalence, Clinical Features, and Ultrasonographic Findings

“…The prevalence of acute and transient thyroid swelling has been reported to be 0.15% (4/2,742 nodules) in one study (8) and 0.13% (1/742 nodules) in another (9). In the larger case series described herein, we estimate the prevalence of this complication to be 0.10% (10/9,596 nodules).…”

“…This difference in the ultrasonographic features of the thyroid parenchyma versus some nodules is presumed to originate from differences in the histologic structure of the two components. Since color-flow Doppler imaging revealed no blood flow signal in the hypoechoic "cracks," as previously reported (5,8), it is possible that these hypoechoic "cracks" reflect fluid accumulation in the loose interstitial space of the thyroid parenchyma. Acute swelling and its spontaneous and relatively rapid recovery also suggest diffuse capillary leakage induced by the puncture of the thyroid parenchyma.…”

Acute diffuse thyroid swelling after fine‐needle aspiration: A case report and review of the literature

“…17 A separate study has reported the rate of blood extravasation-related complications in the range of 1.9% to 6.4%. 18 To date, 15 cases of acute thyroid swelling following an FNA procedure have been reported in the English language literature, [7][8][9][10][11][12][13][14] including the present case. The clinicopathological features of the previously reported cases are summarized in Table 1.…”

“…7 To the best of our knowledge, there have been only 14 cases of this complication reported in the English language literature to date. [7][8][9][10][11][12][13][14] Herein, we report a rare case of acute transient thyroid swelling, which occurred following a US-guided FNA of a thyroid nodule.…”

Airway obstruction requiring tracheal intubation after fine-needle aspiration of the thyroid gland: a case report

“…The overall prevalence of acute, transient thyroid swelling was previously reported to be 0.46% [ 9 ], 0.15% [ 10 ], 0.13% [ 11 ], and 0.10% [ 6 ]. In past reports, this swelling subsided within 1–20 h, and none of the patients developed airway obstruction.…”