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 .
The frequency of this entity is high in the population with immunodeficiency, such as HIV infection, patients receiving chemotherapy, corticosteroids, and transplanted subjects . Our patient was HIV positive.
Clinically, thyroid abscess presents as a painful cervical swelling. Associated signs are dyspnea, hoarseness, dysphonia, dysphagia, and fever . 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 . 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 . 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 . 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 .
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 .
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 .
Among the opportunistic infections associated with the acquired immunodeficiency syndrome (AIDS), cryptococcosis and tuberculosis are the most common life-threatening infection . In the literature, we found a case of Salmonella thyroid abscess in human immunodeficiency virus-positive man  and a case of concomitant tuberculous and cryptococcal thyroid abscess in a human immunodeficiency virus-infected patient .
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