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Benign nodule shrinkage: a diagnosis not to be missed

Abstract

Background

Thyroid nodules presenting ultrasonographic (US) findings suspicious for malignancy should undergo fine-needle aspiration and further cytologic analysis according to the Bethesda 2010 classification. Benign necrotic thyroid nodules may also harbor suspicious US features as follows: ill-defined margins, taller than wide aspect, strong hypoechogenicity, high stiffness index on elastography examination, and reported worrisome cytologic or histologic alterations.

Methods and results

We report the case of a benign thyroid nodule showing shrinkage over time and harboring malignant US features. Fine-needle aspiration cytology examination showed necrosis and no malignant cells.

Conclusions

Precise Doppler US analysis of the nodule and its evolution over time may limit the risk of false-positive diagnosis of thyroid malignancy.

Tumori 2016; 102(Suppl. 2): e101 - e102

Article Type: CASE REPORT

DOI:10.5301/tj.5000422

Authors

Alexis Lacout, Carole Chevenet, Pierre-Yves Marcy

Article History

Disclosures

Financial support: None.
Conflict of interest: None.

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Introduction

Incidental diagnosis of a thyroid nodule is common on adult neck ultrasonographic (US) examination. In such a case, extensive knowledge of thyroid nodule semiology on high-frequency Doppler ultrasound and of the Thyroid Imaging Reporting and Database System (TIRADS) nodule classification is important to detect most thyroid carcinomas (1). Thyroid nodules presenting US findings suspicious for malignancy, such as strong hypoechogenicity, irregular margins, microcalcifications, taller than wide, and stiffness on elastography, should undergo fine-needle aspiration (FNA) and further cytologic analysis according to the Bethesda 2010 classification.

Case report

A 63-year-old woman was referred to our institution for thyroid US (Mylab 70; Esaote, Genova, Italy). Ultrasonographic examination showed a 12-mm ill-defined heterogeneous hypoechoic thyroid nodule with echogenic foci at the right isthmus part of the thyroid (TIRADS 5). The nodule exhibited stiffness on elastography (pattern 3) and displayed a peripheral sharp hypoechoic halo and posterior shadowing (Fig. 1). Doppler US showed neither vasculature nor suspicious cervical lymph nodes.

Thyroid nodule desiccation. (A) Right isthmus 20-mm thyroid nodule harbors benign ultrasonographic (US) features (Thyroid Imaging Reporting and Database System [TIRADS] 2) and posterior reinforcement (arrowhead). (B) One year later, the nodule was smaller (12 mm), harboring US malignant features: strong hypoechogenicity, ill-defined margins, and echogenic foci (TIRADS 5). The nodule also displays a sharp hypoechogenic halo (arrow) and posterior shadowing (large arrow), features that may suggest benignity. Doppler US (not shown) showed no vasculature. (C) Fine-needle aspiration showed solid necrotic yellowish smear material. (D) Cytologic analysis (HES x 10) showed necrosis and no malignant cells.

Previous US examination, performed 12 months before, showed a larger thyroid nodule at the same location (measuring 20 mm), displaying benign features (cystic and solid component, without suspicious US findings), therefore classified TIRADS 2. Benignity was confirmed by FNA during the first examination.

Another FNA was performed and confirmed the diagnosis, showing necrosis features and rare histiocytes, but no malignant cells (Fig. 1).

Discussion

Benign necrotic thyroid nodules may also harbor suspicious US features as follows: ill-defined margins, taller than wide aspect, strong hypoechogenicity, and high stiffness index on elastography examination (2). Furthermore, LiVolsi et al (3) reported worrisome cytologic or histologic alterations following FNA of the thyroid nodule and named it the worrisome histologic alterations following FNA of thyroid (WHAFFT) syndrome. However, the presence of a posterior shadowing and a peripheral hypoechoic and/or hyperechoic halo should suggest the diagnosis of a benign necrotic thyroid nodule rather than malignancy (2). Absence of vasculature is also suggestive of the diagnosis, while it does not definitively rule out the possibility of thyroid malignancy. Fine-needle aspiration may display solid necrotic yellowish smear material while microscopic examination shows necrosis, histiocytes, and no malignant cells. Analyzing the thyroid US modifications over time by using picture archiving and communication system is of prime importance. As long as the benign thyroid nodule that initially harbored benign US features progressively shrinks over time, malignant-like US features will progressively appear.

In conclusion, precise Doppler US analysis of the nodule and its evolution over time may limit the risk of false-positive diagnosis of thyroid malignancy.

Disclosures

Financial support: None.
Conflict of interest: None.
References
  • 1. Russ G Royer B Bigorgne C Rouxel A Bienvenu-Perrard M Leenhardt L Prospective evaluation of thyroid imaging reporting and data system on 4550 nodules with and without elastography. Eur J Endocrinol 2013 168 5 649 655 Google Scholar
  • 2. Koo JH Shin JH Han BK Ko EY Kang SS Cystic thyroid nodules after aspiration mimicking malignancy: sonographic characteristics. J Ultrasound Med 2010 29 10 1415 1421 Google Scholar
  • 3. LiVolsi VA Merino MJ Worrisome histologic alterations following fine-needle aspiration of the thyroid (WHAFFT). Pathol Annu 1994 29 Pt 2 99 120 Google Scholar

Authors

Affiliations

  • Medical imaging center, Aurillac - France
  • Histopathological center, Aurillac - France
  • Radiodiagnostics & oncology imaging department, Polyclinique les fleurs, Ollioules - France

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