Introduction

The thyroid glands’ anatomy, physiology and location make it a well-protected organ from infection. It has a capsule, rich blood supply and lymphatic drainage which together with iodine content prevents it from bacterial infection. Therefore, acute suppurative thyroiditis with abscess is a rare disease with an incidence of less than 1% and represents 0.1% of surgical thyroid pathologies [1, 2].

Thyroid nodules are encountered in 20-60% of population, while they are malignant only in 5-15% of cases [3, 4]. Cystic or partially cystic thyroid nodules are seen in 13-50% of cases and they are malignant in less than 1% of cases [5, 6].

There have been only a few cases of thyroid abscess coexistent with thyroid cancer. We present a rare case of a giant thyroid abscess treated with surgical drainage and hemithyroidectomy that revealed chronic inflammation and underlying papillary thyroid cancer.

Case Description

The 57-year-old female was urgently hospitalized with pain and tenderness of the left side of the neck. The patient had no significant medical or surgical history. He She noticed pronounced swelling of the neck which developed over the night. The subsequent examination revealed the formation of a dense, elastic mass occupying the most of the anterolateral surface of the neck.

The blood count revealed leukocytosis (15*10⁹ [4.0-9.0*10⁹]) There were no deviations in complete blood count, biochemical analysis and blood coagulation panel. However, she had an elevation of T3 – 7.15 pmol/l (normal range 3.8–6 pmol/l) and T4 – 18.22 pmol/l (normal range7.86–14.41 pmol/l), and a normal TSH – 1.79 mcME/ml (normal range 0.34–5.6 mcME/ml).

Ultrasonography revealed pronounced swelling of the neck soft tissues and non-homogenous mass below the skin surface with an approximate size of 13.0 x 10.0 x 12.0 cm, which was spreading behind the sternum.

Contrast-enhanced CT of the neck demonstrated thyroid gland left lobe lesion with the size of 13.4 x 10.2 x 12.0 cm with a thin capsule, which contained fluid component with sings of calcification and accumulated contrast at the periphery, tracheal compression by 50% and massive locoregional lymphadenopathy (Figure 1-4).

Figure 1: CT of the neck. A – Giant abscess (frontal section), B – Giant abscess (sagittal section).	Figure 2: CT of the neck. A – Giant abscess, B – Tracheal compression
Figure 3: Ultrasonography of the neck. A - drainage tube inside the abscess cavity (convex probe), C - drainage tube, the scan performs echogenic masses inside the cavity (convex probe), E - drainage tube inside the abscess cavity (linear probe); B, D, F - abscess cavity marked in yellow, drainage tube marked in green
Figure 4: CT of the neck. A – First drainage B – Second drainage	Figure 5: Fine needle liquid aspiration for cytology exam
Figure 6: Postoperative specimen A – Section B - Size
	Figure 7: Postoperative histology

Abscess of the thyroid gland left lobe cyst was suspected. After thorough examination, respiratory failure was excluded (SaO2 95%, respiratory rate 16 respirations per minute, no dyspnea MRC scale 0). The patient was seen by a surgeon on call, endocrine surgeon, ENT surgeon, endoscopy specialist and anesthesiologist for planning further tactics. Considering the patient's stable condition, it had been decided to perform ultrasound-guided drainage of the formation under local anesthesia (Figure 3). In case of complications or technical difficulties, it had been considered to continue the operation under general endotracheal anesthesia. The skin in the lateral aspect of the neck was anesthetized with 2% lidocaine solution. Two drainages were introduced under USG-guidance. Pus-like solution obtained after drainage (Figure 5). However, pus culture was negative for bacteria. The patient’s laboratory values normalized over a week period. Her leukocyte level decreased from 15 to 10*10⁹ and CRP from 82 to 14 u/l. In the postoperative period the patient's vital signs were within normal and he received conservative therapy in the extent of cefoperazone sulbactam, metronidazole, proton pump inhibitor (omeprazole 20 mg 2 times daily) and NSAID (ketorol) for adequate pain control. Antibiotic therapy was discontinued after negative pus culture. Laboratory monitoring and dynamic observation were performed. Cytology report of the lesion contents stated the presence of chronic abscess and the thyroid gland left lobe tumor of undetermined malignancy potential (Bethesda III). Consequently, the patient underwent radical left hemithyroidectomy in a planned manner.

The patient was operated under general anesthesia. The thyroid gland was exposed through a collar incision on the anterior surface of the neck, without crossing the pretracheal muscles. During revision, the left lobe was 4.5×3.5×1.5 cm, the right lobe was 3.0 ×2.0×1.5 cm, and the isthmus was 1.0 ×1.0×0.5 cm. The entire left lobe of the thyroid gland was occupied by a volumetric formation of dense-elastic consistency up to 4 cm in diameter. We performed a hemithyroidectomy with visualization of the recurrent laryngeal nerve. The surgical material was sent for histological examination (Fig. 3). A drain was inserted for active aspiration from the wound followed by layer-by-lay-er wound suture. The surgical specimen examined contained fragments of the thyroid gland with a morphological appearance of a nodular colloid goiter and an encapsulated nodule with secondary changes in the form of hemorrhages, the wall of which was represented by fibrous tissue (Figure 6).

Specimen histological picture met criteria of papillary thyroid cancer, infiltrative follicular variant, pT3aN0M0 with signs of lymphovascular invasion (Figure 7). She received hormonal suppressive therapy with 150 mcg of thyroxine and there was no cancer progression two years after surgery.

Discussion

Thyroid abscess is a life-threatening condition with and overall mortality rate over 3.7%-12% [7, 8]. This is a rare clinical entity and there are approximately 200 cases described in the literature in 20 years [8]. However the anatomical localization of the thyroid gland makes it easy to lead to a number of conditions such as thrombophlebitis, mediastinitis/pericarditis, oesophageal perforation, fistula and obstruction, laryngeal oedema, obstructive symptoms, multisystem organ failure which in turn can lead to a mortality rate of mortality rate 14–42% [8-10].

Although thyroid abscess is rare, its association or with cancer is reported in only a few cases (table 1).

Anaplastic thyroid carcinoma can mimic a thyroid abscess due to its rapid, destructive growth, which causes severe neck pain, swelling, and redness, often misleading initial diagnosis [16].

Bacterial acute suppurative thyroiditis is managed with antibiotics, aspiration and surgery. Multiple needle aspirations are usually required in 3% of cases. Surgery often includes hemithyroidectomy, excision of fistula or total thyroidectomy [8]. The current case is different as the patient undergone percutaneous drainage for thyroid abscess due to large size and volume of the abscess.

The most common pathogens in acute suppurative thyroiditis are Streptococcus spp. and Staphylococcus spp [8]. However sometimes the culture can be negative and can be seen in malignant processes (table 1).

The main goals of treatment include removal of pus and stabilization of the patient [8]. If unstable, it is crucial to look for and treat any airway compromise, sepsis and/or thyrotoxicosis as appropriate [8,17].

Conclusions

Thyroid cancer as any neoplasia can be promoted by chronic inflammation or produce signaling factors inducing inflammatory process. As in this case, a male patient was treated for thyroid abscess, but eventually he was diagnosed with papillary thyroid cancer. Since a risk of having cancer increases with age, older patients should be monitored more closely for the presence of malignancy.

Ethics Approval and Consent to Participate

The patients have provided written informed consent to participate in the study.
Competing Interests

References

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