Thyroid abscess in a human immunodeficiency virus-infected patient

Thyroid abscess is a rare entity and occurs in patients in a particular situation either in an immunocompromised patient or on tuberculosis infection since the African countries are still tuberculosis endemic countries We report the case of a 38-year-old female patient who has a thyroid abscess caused by Citrobacter which is a rare germ. Screening for human immunodeficiency virus (HIV) was positive for HIV infection. Screening for HIV and other causes of immunosuppression should be considered in any patient with thyroid abscess.


Background
Thyroid abscess is a rare entity and occurs in patients in a particular situation [1], either in an immunocompromised patient or in a tuberculosis infection since Morocco and African countries are still tuberculosisendemic countries [2]. We will report the case of a patient who presented with a thyroid abscess associated with an HIV infection.

Case presentation
A 38-year-old female with no previous medical history, no previous goiter, who presented a cervical pain and tumor that had been evolving for several days. On examination, the patient had a fever at 38 °C, tachycardia at 110 bpm, on cervical examination: goiter on the right lobe, very painful on palpation, and hard consistency with inflammatory signs (red and warm) (Fig. 1).
The biological workup showed an inflammatory syndrome: high CRP at 130 mg/l, leukocytes at 7890/mm 3 , and TSH low at 0.05 mUI/ml The cervical ultrasound showed an aspect in favor of thyroid abscess completed by a CT scan which showed an enlarged thyroid with a collection at the expense of the right thyroid lobe measuring 43 × 36 × 24 mm (Fig. 2).
The ultrasound-guided fine-needle aspiration with a cytobacteriological study of the pus showed direct examination, no germ in favor of a tuberculosis infection and identification of Citrobacter.
The screening for human immunodeficiency virus was positive for HIV infection, and the patient had no other symptoms of HIV infection.
The patient was put on antibiotics, and the abscess was fistulized to the skin ( Fig. 3) completed by a surgical drainage. (There is no photo after completed healing.)

Discussion
Thyroid abscess is an extremely rare pathological entity, representing only 0.1% of surgical thyroid pathologies. It is an unusual situation due to the anatomical and physiological characteristics of the gland which gives it a capacity of resistance towards infection [3].
The frequency of this entity is high in the population with immunodeficiency, such as HIV infection, patients receiving chemotherapy, corticosteroids, and transplanted subjects [4]. Our patient was HIV positive.

Open Access
The Egyptian Journal of Otolaryngology Clinically, thyroid abscess presents as a painful cervical swelling. Associated signs are dyspnea, hoarseness, dysphonia, dysphagia, and fever [5]. Biologically, there is an inflammatory syndrome with increased CRP, hyperleukocytosis as in our patient's case.
Thyroid function in patients with thyroid abscesses is usually not affected. However, transient thyrotoxicosis secondary to disruption of thyroid follicles and release of preformed thyroid hormones may occur; this mechanism is similar to thyrotoxicosis in patients with subacute thyroiditis [6]. Our patient presented with hyperthyroidism with a suppressed TSH.
The etiologies of thyroid abscesses are multiple; streptococcal and staphylococcal infections are very frequent and represent 70% of cases [7]. However, other germs have also been reported in the literature. Mycobacteria, although rare, exist and are reported in the literature. Their localization in the thyroid represents 0.1 to 0.4% of all tuberculosis localizations and are usually multiple simulating a multinodular goiter [8]. In our case, the germ identified on the pus culture was Citrobacter which is a gram-negative bacterium that occurs mainly in immunocompromised patients. Infections due to this pathogen are relatively rare [9].
Ultrasound and cervical CT scan are the examination of choice in the study of the structure of the abscess, the number of compartments, its size, and its reports to adjacent anatomical structures, particularly with the vascular-nervous bundle of the neck and the upper airways [10].
The diagnosis is confirmed by fine-needle aspiration which brings pus. The cytobacteriological study allows the isolation of the causal germ and the study of its sensitivity to antibiotics.  The treatment is based on draining of the abscess with appropriate antibacterial therapy. If left untreated, the thyroid abscess can have unfortunate consequences on the surrounding organs. It can result in the destruction of the thyroid glandular parenchyma and parathyroids, a thrombophlebitis of the jugular vein. Fistulization of the abscess in the esophagus or in the tracheal lumen, external fistulization to the skin. Sepsis and blood dissemination to distant organs [11].
Among the opportunistic infections associated with the acquired immunodeficiency syndrome (AIDS), cryptococcosis and tuberculosis are the most common lifethreatening infection [7]. In the literature, we found a case of Salmonella thyroid abscess in human immunodeficiency virus-positive man [7] and a case of concomitant tuberculous and cryptococcal thyroid abscess in a human immunodeficiency virus-infected patient [1].

Conclusions
Thyroid abscess is a rare entity and occurs in a particular context of immunosuppression. The diagnosis is often made by ultrasound and pus punction. Treatment is based on drainage and antibiotics. Screening for HIV and other causes of immunosuppression should be considered in any patient with a thyroid abscess.