August 3, 2007
Thyroid Abscess: Case Report and Review of the Literature
By Herndon, Mark D Christie, D Benjamin; Ayoub, Macram M; Duggan, A Daniel
A thyroid abscess is an infrequently encountered condition with a rarity that is attributable to anatomic and physiologic characteristics of the gland that impart a unique quality of infection resistance. The differential diagnoses for a painful thyroid is limited, with subacute and chronic thyroiditis being the most often-encountered processes. Acute suppurative thyroiditis with abscess formation, although rare, is a formidable clinical scenario with morbid complications. Because the diagnosis of a thyroid abscess is often delayed in lieu of investigating other more common etiologies of thyroiditis, this disease entity may portend to a dismal clinical outcome. The authors report the case of a 53-year- old woman with a thyroid abscess yielding a single microbial isolate believed to be resultant from a urinary tract bacteremia. They also review the literature for discussion of abscess etiologies, presentations, and management strategies. A THYROID ABSCESS is an infrequently encountered condition with a rarity that is attributable to anatomic and physiologic characteristics of the gland that impart a unique quality of infection resistance. When discovered, a thyroid abscess usually presents acutely as a painful, enlarging mass. The differential diagnoses for a painful thyroid is limited, with subacute and chronic thyroiditis being the most often encountered processes. Acute suppurative thyroiditis with abscess formation, although rare, is a formidable clinical scenario with morbid complications. We report the case of a 53-year-old woman with a thyroid abscess yielding a single microbial isolate believed to be resultant from a urinary tract bacteremia.
A 53-year-old woman presented to our institution with the chief complaint of an acute onset of pain and swelling of the right side of her anterior neck. The pain was described as constant and radiating to the right posterior occiput. The patient admitted to fever, chills, diaphoresis, headache, and nausea, all of which corresponded to the onset of the pain and swelling. She denied, however, any dyspnea, dysphagia, and odynophagia. She had a past medical history of a longstanding goiter and aortic valve replacement, and a remote history of a pilonidal cyst infection treated with excision and intravenous antibiotics. The patient also revealed a recent past medial history of a dental procedure for which she was completing a prophylactic antibiotic course. Her medications at that time included warfarin and a firstgeneration cephalosporin. On physical examination the patient appeared ill and in a moderate degree of distress. Stridor was not present and her breath sounds were normal bilaterally. The right anterior aspect of her neck demonstrated an erythematous hue and was warm to the touch. The right lobe of the thyroid gland was markedly enlarged and exquisitely tender. Cervical or supraclavicular adenopathy were not present.
Significant findings in her laboratory profile included thyroid function studies reflecting a euthyroid state, an international normalized ratio (INR) of 8.1 and a white blood count (WBC) of 22,000. Urine and blood cultures were taken, both of which would eventually reveal Escherichia coli positivity; however, broad- spectrum antibiotics were administered empirically. Ultrasound of the thyroid gland demonstrated a complex, cystic-appearing right thyroid lobe suspicious for hemorrhage, and a CT scan of the neck confirmed ultrasound findings and did not identify any airway compression.
A few hours after efforts to correct her coagulopathy were begun, she exhibited a moderate degree of respiratory distress, was intubated, and transferred to the intensive care unit. The next day she was taken to the operating room for exploration of the neck. The right thyroid lobe was found to be extremely tense and friable. The anterior wall of the gland was cannulated and 100 mL of foul- smelling purulent fluid was aspirated. Cultures were obtained and E. coli was eventually isolated. An uneventful right lobectomy with drain placement was performed. The patient was extubated during the postoperative period, remained euthyroid, and was discharged home 4 days later after an uneventful hospital course.
The thyroid gland is particularly resistant to infection and rarely demonstrates suppurative processes. As such, the diagnosis of thyroid abscess is often left off a physician's differential. Some have postulated the thyroid owes its resistance to infection to 1) its rich blood supply, 2) the capacity of lymphatic drainage, 3) the inhibiting effect of the gland's iodine content, and 4) the protective fibrous capsule of the gland. ' Canine studies have revealed that direct inoculation of Staphylococcus and Streptococcus species into the superior thyroid artery infrequently leads to abscess formation,2 a finding that is believed to be resultant from anatomic and physiologic characteristics particular to the thyroid. The gland's encapsulated and iodine-replete environment, secluded anatomic location, extensive lymphatic effluence, and pervasive vascularity are theorized to protect the thyroid from bacterial invasion and overgrowth.3-7
Abscess formation of the thyroid most commonly arises in the pediatric population in the setting of anatomic anomalies of the hypopharyngeal region, leading to the development of a pyriform sinus fistula.7 Patients with developmental defects of this sort usually demonstrate recurrent inflammatory events and are eventually diagnosed after a barium contrast swallow study reveals a fistulous tract. In the adult population, multiple etiologies have been proposed. Abscess development secondary to direct trauma from foreign bodies, such as fine-needle aspiration, fishbone, and chicken bone penetration, have been described, as well as extension from neighboring anatomic structures.8-10 However, hematogenous spreading from a distant site is considered to be the most common cause of infection, even though the exact infectious source or pathway is frequently unknown.6- ' ' Sources believed to have hematogenously seeded the thyroid include pilonidal abscesses,12 infections of the hand, ' 3 and possible inoculation from intravenous drug abuse. The most common causative organisms have historically been Staphylococci and Streptococci species, and cultures are more often polymicrobial. Other organisms isolated such as Acinetobacter, Mycobacterium, Coccidioides, Pseudomonas, Salmonella, Eikenella, Clostridium, Nocardia, Pneumocystis carnii, Haemophilus, and Candida species have been identified, although they are mostly associated with immunosuppressed patients.6, 14-22
Because of its rarity, the incidence of thyroid abscess formation is difficult to identify. The data are equivocal regarding whether thyroid abscesses occur more frequently in men or women. Hazard et al.8 observed a more common occurrence in women in the age range of 20 to 40 years, whereas large reviews by Yu et al.23 and Berger et al.24 both revealed a more uniform distribution among the sexes. The reported age range for abscess formation is broad, having been reported in patients from 1 6 months to 77 years of age, and the frequency of this entity is increased in the immunocompromised population, such as seen with human immunodeficiency virus positivity, patients receiving chemotherapy or steroids, and transplant recipients.
Clinically, thyroid abscess often presents with an acute onset of pain and swelling frequently after an upper respiratory, pharyngeal, or middle ear infection. Associated signs and symptoms include point tenderness, dyspnea, pain that may radiate posterior and laterally, hoarseness, dysphagia, fever, and chills.25 Infrequently the condition may present as a pulsatile mass26 or with vocal cord paralysis,27 and asymptomatic cases have also been reported.28
Because thyroid abscess formation is so infrequently encountered, the differential diagnosis usually begins with viral subacute thyroiditis, because these patients also complain of neck pain and thyroid tenderness, but systemic symptoms of hyperthyroidism are often present. Initially, acute suppurative thyroiditis may be difficult to distinguish from subacute thyroiditis. On examination, the thyroid of subacute thyroiditis is typically extremely tender and mildly to moderately enlarged. The enlargement is often diffuse, but may be unilateral with the gland demonstrating focal nodularity and a consistency that is firm to hard.29 A steroid trial has become the initial management strategy for viral subacute thyroiditis, and because this maneuver may detrimentally exacerbate a suppurative process of the thyroid, a heightened sense of clinical suspicion is required to delineate the two processes. Painful chronic thyroiditis, also in the differential of a painful thyroid, can have a transient hyperthyroid phase and may initially be indistinguishable from subacute thyroiditis,30 and in turn a suppurative process of the thyroid. In painful chronic thyroiditis, the white blood cell count and erythrocyte sedimentation rate are lower than in subacute thyroiditis, the antimicrosomal antibody titer is usually elevated, and eventual hypothyroidism is common.29 Other etiologies for a painful thyroid include primary and metastatic neoplasms, amyloidosis, amiodarone associated thyrotoxicosis, P. carinii infection, hemorrhage, Grave's disease, and infarction of a thyroid nodule.29 Abnormal laboratory findings suggestive of acute suppurative thyroiditis include a leukocytosis, an elevated erythrocyte sedimentation rate, and thyroid functional studies that may be normal to mildly hyperthyroid.29, 31 As expected, thyroid scans often demonstrate hypofunctional areas with decreased tracer uptake,29 and plain radiographs may reveal esophageal or tracheal displacement.6 Sonography and CT are helpful in identifying the underlying abscess structure and extent of its involvement. CT scan is particularly useful to investigate for anatomic defects or fistulous formation, especially in the younger patient and for those with recurrent processes. The application of CT scan and barium swallow is recommended to assess for the aforementioned anatomic anomalies after the acute inflammatory process resolves in this patient population.2, 6, 31-33 Despite the degree of anatomic detail that these imaging modalities allow, it is universally agreed that a simple fine-needle aspiration can confirm the diagnosis of a thyroid abscess and determine both the causative organism and its antibiotic susceptibility.
If left unchecked, the thyroid abscess portends to a dismal clinical outcome. Complications of this infectious process result in destruction of the thyroid or parathyroid glands, internal jugular vein thrombophlebitis, either abscess rupture or fistula formation into the esophagus or trachea, local or hematologic spread to other organs, and sepsis.6, 29, 34 Management involves surgery with either lobar excision or debridement, resection of a fistulous connection if applicable, combined with culture-appropriate antibiotics. Because this disease entity is rapidly progressive and often delayed in its presentation, early recognition and intervention are necessary to curtail the morbid potential of the complications of this process.
A thyroid abscess is a rare condition and, because it is so infrequently encountered, the diagnosis may be delayed in lieu of investigating the more common etiologies of thyroiditis. The discovery of a thyroid abscess, especially if recurrent or in the younger patient, should remind the clinician of possible anatomic anomalies or fistulous connections, and the need for detailed imaging studies when the acute inflammatory process resolves. When suspected, fine-needle aspiration can quickly provide a diagnosis, and surgical debridement or lobectomy with culture-appropriate antibiotics usually results in a successful clinical outcome.
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MARK D. HERNDON, M.D.,* D. BENJAMIN CHRISTIE, M.D.,* MACRAM M. AYOUB, M.D.,* A. DANIEL DUGGAN, M.D.[dagger]
From the * Department of Surgery, Mercer University School of Medicine, Medical Center of Central Georgia, Macon, Georgia; and the [dagger] University Hospital, Augusta, Georgia
Presented during Poster Grand Rounds at the Annual Scientific Meeting and Postgraduate Course Program, Southeastern Surgical Congress, Savannah, Georgia, February 10-13, 2007.
Address correspondence and reprint requests to Mark D. Herndon, M. D., Department of Surgery, Medical Center of Central Georgia, Hospital Box 140, 777 Hemlock Street, Macon, GA 31201. E-mail: [email protected]
Copyright Southeastern Surgical Congress Jul 2007
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