Infectious Diseases in Clinical Practice:
Brucellar Thyroid Abscess: Case Report and Review of the Causes and Management of This Rare Medical Entity
Starakis, Ioannis MD, PhD*; Stoubou, Vasiliki MD*; Siagris, Dimitris MD, PhD*; Alexandridis, Theodoros MD, PhD†; Petrochilos, Ioannis MD, PhD‡; Karatza, Chrysoula MD, PhD*
*Departments of Internal Medicine, †Endocrinology, and ‡Surgery, Patras University Hospital, Patras, Greece.
The authors do not have any commercial or other association that might pose a conflict of interest. There are not any sources of financial support. This work has never been presented in any form before.
Address correspondence and reprint requests to Ioannis Starakis, MD, PhD, Department of Internal Medicine, Patras University Hospital, 26500 Rion, Patras, Greece. E-mail: firstname.lastname@example.org.
Infections of the thyroid are quite rare but may be life threatening. Thyroid abscess resulting from acute suppurative thyroiditis is a rare clinical entity. The infection may engage one or both lobes, and abscess formation may not be evident until late in the course of the disease. We report a case of a woman who presented with acute thyroiditis and eventually developed thyroid abscess. The causal organism was found to be Brucella melitensis. Antibiotic treatment and removal of the abscess led to an uneventful recovery.
Acute suppurative thyroiditis (AST) leading to thyroid abscess is a rare clinical entity, representing less than 1% of all brucella complications and 0.1% to 0.7% of all surgically treated thyroid diseases.1 Gram-positive organisms such as staphylococcus or streptococcus species are most commonly implicated, and Gram-negative suppurative thyroiditis is rarely reported. Because of its scarcity and unusual clinical aspects, the diagnosis of suppuration in thyroid gland is often delayed, and progression to abscess formation may occur. The authors present a case of thyroid abscess in a woman caused by Brucella melitensis, an organism very rarely implicated in the pathogenesis of this disease. Cases of brucellosis and brucellar abscess are unusual in developed countries because brucellosis has practically been eradicated in animals, but brucellosis in Greece still is one of the most frequent zoonosis. To the best of our knowledge, this latter complication has not been previously described in Greece.
An 87-year-old woman, referred from a regional hospital with a diagnosis of "subacute thyroiditis," was admitted to our university hospital. One week before her admission, the patient, who lived in a rural area, had presented to her primary care physician with a preceding history of a respiratory tract infection, complaining of neck pain radiating to the anterior chest wall, fever up to 39°C, and a nonproductive cough. She was found to have an enlarged and painful thyroid gland. Ultrasound examination of the gland was unremarkable, and a fine-needle aspiration of thyroid was performed. A moderate infiltration with polymorphonuclear leukocytes, along with few lymphocytes and erythrocytes, was noted. Many follicles had been replaced by an inflammatory reaction, but a few follicles containing colloid remained. Based on these results and in combination with the clinical findings, thyroiditis was diagnosed, and oral aspirin was prescribed. Nevertheless, the patient deteriorated and developed severe malaise and exhaustion, and for this reason, she presented to our hospital. The patient had mild hypertension and had a 7-year history of rheumatoid arthritis. She was on methylprednisolone 8 mg/d PO, for the last 2 years. On admission, she was mildly dehydrated and appeared moderately ill. Temperature was 39°C; blood pressure, 110/60 mm Hg; pulse rate, 110/min; and respiratory rate, 26 breaths per minute. Examination of the neck revealed an enlarged thyroid gland that was mildly painful to palpation, without erythema or local warmth. Chest examination result was unremarkable, and the remaining examination was without significant findings. Laboratory evaluation on admission demonstrated a leukocyte count of 11.4 × 109/L (75% neutrophils, 15% lymphocytes, and 10% mononuclear cells). The hematocrit was 32.2%; hemoglobin level, 10.2 g/dL; and platelet count, 18× 109/L. The erythrocyte sedimentation rate was 115 mm/h, and blood biochemistry profile was normal. The findings from her chest radiographs were normal. Triiodothyronine was 78 ng/dL (normal, 70-190 ng/dL); thyroxine, 125 nmol/L (normal, 64-154 nmol/L); and thyroid stimulating hormone, 0.50 mU/L (normal, 0.4-5 mU/L). No thyroid autoantibodies were detected. Specimens for cultures of blood and urine were obtained. Thyroid technetium Tc 99m scan demonstrated an enlarged gland and reduced uptake in the lower pole of the right lobe of thyroid, suggesting a "cold" nodule and not subacute thyroiditis. Urine culture yielded Klebsiella oxytoca, and trimethoprim-sulfamethoxazole was administered intravenously. Patient gradually improved, and she remained afebrile after 3 days and was transferred back to the regional hospital to conclude the course of therapy. Two weeks after her transfer, patient was readmitted to our hospital because of recurrence of fever up to 38°C, with severe neck pain and difficulty of swallowing solids and liquids. On physical examination, the enlarged thyroid gland was very tender to palpation. There was a large swelling occupying the region of the thyroid gland, more prominent on the right than the left side, and the overlying skin was warm and erythematous, but no fluctuation was apparent. Swallowing aggravated the pain. Blood and urine cultures were obtained, and ticarcillin-clavulanate in combination with vancomycin was administered intravenously. Laboratory evaluation demonstrated a leukocyte count of 5.3 × 109/L (60% neutrophils, 27.7% lymphocytes, 8.5% mononuclear cells, 3.4% eosinophils, and 0.4% basophils). The hematocrit value was 0.36; hemoglobin level, 11.1 g/dL; and platelet count, 19 × 109/L. The erythrocyte sedimentation rate was 106 mm/h, and blood biochemistry profile was normal. The Wright agglutination test for brucella was positive at titers of 1:640. A computed tomography of the thyroid revealed 2 cystic areas in the right lobe and the isthmus of the gland that did not enhance with contrast. A fine-needle aspiration of the thyroid fluctuant mass was performed, and culture yielded B. melitensis. Blood cultures also isolated B. melitensis. Rifampicin (600 mg/d) and doxycycline (200 mg/d) were added to the antibiotic regimen. A detailed history revealed that the patient was occasionally consuming unpasteurized milk and fresh cheese. Patient's condition deteriorated the next 2 days, with high fever and development of necrotic skin areas and sinus tracts over the fluctuant right lobe mass. She was operated, and the right thyroid lobe and isthmus were removed. Patient had an uneventful course and was discharged 5 days after the operation. A barium esophagogram performed after her discharge and also repeated 7 months later failed to reveal a pyriform sinus fistula (PSF). Rifampicin (600 mg/d) and doxycycline (200 mg/d) were prescribed for 3 months, and doxycycline alone was administered for 6 more months.
Infections of thyroid are rare because the gland is resistant to infection because of its encapsulation, high iodide content, prosperous blood supply, wide lymphatic drainage, and separation of the gland from other structures of the neck by fascial planes. Hendrick2 reported that 24% of 117 reviewed patients with thyroiditis appeared with an acute form of the disease, and only 5% of them finally developed an abscess. Infectious thyroiditis may be either acute or chronic. Acute suppurative thyroiditis can lead to abscess formation, if left untreated, and is usually caused by Gram-positive or Gram-negative organisms. Staphylococcus aureus predominates but pneumococcal, salmonella, mycobacterial, parasitic, fungal, and pneumocystis infections may also occur. Mixed infections involving oropharyngeal flora and anaerobic bacteria can also occur.3 Although Hazard4 in 1955 and Yu et al5 40 years later described staphylococci and streptococci as the 2 most frequent causative agents of AST, a wide range of other microorganisms have been associated and recognized in thyroid infection (Table 1). Acute suppurative thyroiditis most likely occur in patients with preexisting thyroid disease (thyroid cancer, Hashimoto thyroiditis, or multinodular goiter), those with congenital anomalies such as a PSF that usually extends to the left lobe of the thyroid (the most frequent source of infection in children), those with immunosuppression, and in elderly or debilitated patients. The condition also occurs in patients with the acquired immunodeficiency syndrome, in whom opportunistic thyroid infections such as Mycobacterium tuberculosis, cytomegalovirus, cryptococcus species, Mycobacterium avium, Rhodococcus equi, Streptococcus pneumoniae, and Pneumocystis carinii have been reported.6 Occasional neonatal cases have also been reported.7 Acute suppurative thyroiditis usually presents with sudden onset of anterior neck pain that may radiate to the chest, mandible, or ear and tenderness that is usually unilateral and is accompanied by fever and other symptoms and signs of infection. Sore throat, dysphonia, and dysphagia may also be present. The gland is tender to palpation, and the overlying skin is warm. Although fluctuation was not present in our case, it may not be evident because of the edema and infiltration of the adjacent tissues. Preceding history of an upper respiratory tract infection may be present, as was the case with our patient. Hematogenous seeding from a distal site of infection may be the most common cause of thyroid infection, although the precise infectious source is often unidentified. Congenital abnormalities such as PSF and trauma may also predispose to thyroiditis with abscess formation.8 Patients with AST are usually euthyroid, and no thyroid autoantibodies are detected, but both thyrotoxicosis and hypothyroidism have been reported.9 More chronic thyroid infections often involve both lobes, pain and tenderness are less prominent, and some patients have hypothyroidism. Fungal, parasitic, and mycobacterial thyroiditis and also opportunistic thyroid infections in patients with acquired immunodeficiency syndrome usually have an insidious and chronic course. Thyroid abscesses have been observed more commonly in women than in men,4 but there are reports demonstrating that the disease occurs in men and women in a 1:1 ratio.5 The age range may vary considerably, and patients aged from 16 days to 79 years have been reported.10 Laboratory features include elevated erythrocyte sedimentation rate and possibly an elevated white blood count with a left shift. Radioactive-iodine scanning may be normal or show hypofunctional areas with decreased uptake or suppurative areas appearing as "cold" nodules. Ultrasound and computed tomography scanning may demonstrate the underlying configuration and extent of the abscess and potential local irregularities in thyroid anatomy. Most authorities agree that a barium esophagram should be done after infective process subsides to look for an occult PSF. In these cases, reconstructive surgery is essential to avert recurrence of abscess formation. In our patient, no PSF was found by 2 barium esophagrams, done after her discharge. The essential steps in evaluation are fine-needle aspiration biopsy with Gram staining and culture of the thyroid to identify the causative organism. Empirical broad-spectrum antibiotic therapy with Gram-positive cocci coverage should be started early when a thyroid abscess is suspected. Surgery is the most frequently recommended management of a thyroid abscess, consisting of either excision or drainage, combined with suitable parenteral antibiotic treatment, although a minority has the opinion that thyroid abscesses can be treated with antibiotics alone and surgery should be used only if antibiotics not succeed.11 Prognosis is very good, with maintenance of thyroid function, and long-term thyroid dysfunction is uncommon. Acute suppurative thyroiditis is most often seen in patients who are immunocompromised or otherwise debilitated. The extreme of age and also the immunomodulation caused by the corticosteroids might have been the precipitating factors for our patients having such as unusual infection in this unusual site. Our search in the medical literature during the last 60 years came up with only 4 case reports with 7 patients having brucella infection of the thyroid gland (Table 1). This case report and review of the literature denotes that physicians are important to keep an open mind and exclude less common causes of AST and thyroid abscess. For that purpose, it is mandatory to obtain specimens for suitable microbiological cultures before introducing antibiotic therapy.
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