Pseudoempyema in an Indigenous Australian child: occurring via a rare route

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A 2‐year‐old Indigenous Australian girl presented with her parents to a remote Northern Australian hospital with a 24‐h history of lethargy, fever and reduced oral intake. She had been previously well without any preceding nor current respiratory tract symptomatology and the only past medical history described by her parents was that of a single ‘boil’ located in the right occipital region of her scalp 3 weeks prior to presentation. This isolated folliculitis or furuncle had been lanced and had resolved completely by the time of presentation. Physical examination revealed a tender right supraclavicular mass and ultrasonography of this mass visualized a fluid collection between the muscles of the neck and additionally discovered a complex collection in the right upper thorax. Initial plain chest radiography demonstrated right upper zone opacity suggestive of right upper lobar pneumonia and later plain radiography demonstrated a well demarcated loculated lesion more suggestive of a pleural empyema (Fig. 1). Blood cultures failed to reveal any microorganism. Despite a progressively varying antibiotic regimen consisting of intravenous flucloxacillin, benzylpenicillin, cefotaxime and later vancomycin, the patient continued to have fevers of 39°C and the chest lesion continued to increase in size on plain chest radiography, warranting transfer to a tertiary care centre for further evaluation and management.
Computed tomography with contrast established the presence of a large fluid‐filled lesion occupying much of the right superior thorax surrounded by a rim of thickened pleura and compressed lung tissue (Fig. 2). The supraclavicular mass demonstrated matted inflammatory lymph nodes and a lucent zone and this pathology extended around the lateral aspect of the right upper chest and beneath the scapula. The thoracic and neck lesions appeared to be in direct continuity. Despite the large intrathoracic component, the child did not have respiratory symptoms.
In the operating room, an ultrasound‐guided needle thoracocentesis confirmed the presence of fluid and the tract was then extended to thoracostomy, draining 70 mL of frank yellow pus. The dissection remained extra‐pleural. An intercostal drain was placed. The retrieved pus cultured methicillin‐resistant Staphylococcus aureus (MRSA) that later proved to be positive for Panton–Valentine leukocidin (PVL).
The patient commenced a 6‐week course of intravenous lincomycin. The drain was removed at 24 h. Subsequent X‐ray and ultrasound imaging demonstrated resolution of the collection.
Our hypothesis for the development of this child's pathology involves the initial follicular infection with S. aureus (of MRSA PVL‐positive strain) in the right occipital region of the scalp. Lymphatic drainage of this region is to the inferior deep cervical nodes via the occipital nodes and as such transferred the microorganism to this group of nodes. Although the scalp lesion resolved, the underlying suppurative lymphadenopathy progressed resulting in the cervical collection, tracking deep to the sternocleidomastoid through the ipsilateral thoracic inlet, proliferating into a large abscess (Fig. 3).
Community‐acquired methicillin‐resistant S. aureus infection is a common occurrence in Northern Australian communities especially among the indigenous subpopulation.1 PVL‐positive strains are recognized as being especially associated with infection of skin and soft tissues because of the dermonecrotic property of the leukocidin; however, recent review has suggested that invasive S. aureus disease is independent of PVL status.3 Large non‐traumatic mediastinal S. aureus abscesses in the paediatric population forming via the descending extension of neck abscesses have been described; however, these follow more clearly defined classical anatomical routes via potential spaces of the neck.4 While S. aureus abscesses of the neck resulting from suppurative cervical lymphadenopathy are well recognized, there are no reports of extension of such collections into the thoracic cavity to our knowledge.6
This case demonstrates a very unusual extension of an MRSA cervical abscess, which was not apparent on physical examination alone.
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