Natasha Gupta1, Arpita Chattopadhyay2, Rutuja Kishor Nyayadhish3, Diganta Saikia4
Corresponding author: Dr. Arpita Chattopadhyay, Assistant Professor (Pediatrics), Chacha Nehru Bal Chikitsalaya, Geeta Colony, New Delhi. Chattopadhyay.arpita@gmail.com
1 Specialist (Radiology),2 Assistant Professor (Pediatrics),3 Postgraduate Trainee (Pediatrics),4 Professor (Pediatrics)
Affiliation: Chacha Nehru Bal Chikitsalaya, Geeta Colony, New Delhi.
To the Editor,
Necrotising pneumonia complicated by mycotic pseudoaneurysm has been reported very rarely in infancy. Here we present a five month old girl who had an acute life-threatening presentation of cavitatory pneumonia.
A five month old girl presented with painful swelling and induration over right lower limb, below the knee joint, associated with high grade fever for 15 days. For this complaint she was taken to a local practitioner where she was advised incision and drainage of underlying collection along with a course of intravenous antibiotics. However, although the limb swelling subsided, high grade fever persisted. She progressively developed rapid breathing over 5 days and presented to our tertiary care centre in respiratory failure.
Examination revealed a sick child with respiratory rate – 74/min, HR- 186/min, saturation 81% on room air along with severe suprasternal and subcostal retractions, diminished breath sounds over right hemithorax. Laboratory indices suggested neutrophilic leukocytosis with high C-reactive Protein. A Chest X Ray was obtained (Fig 1A), which showed multiple large sized thin walled, cystic lesions in entire right lung field and left lower zone in retrocardiac region, suggestive of pneumatoceles, with the largest lesion in the right lower lung showing an eccentric rounded mass within the cavity, projecting inside from its medial wall (Figure 1).
Due to impending respiratory failure, child was emergently intubated after shifting to the PICU and put on mechanical ventilation. After 2 hours of mechanical ventilation child suddenly began to desaturate despite titration in settings. A repeat x-ray revealed a large area of relative lucency with absent bronchovascular markings in the right hemithorax, suggesting a pneumothorax. An emergent rightside intercostal drain was inserted. The drain emptied 100 ml of purulent fluid in the next three days. Subsequently over the course of five days, the child was gradually weaned off mechanical ventilation and shifted to humidified high flow nasal cannula. Blood culture came positive for Methicillin Resistant Staphylococcus aureus sensitive to Vancomycin and Linezolid.
As tachypnea persisted, a contrast enhanced CT scan of the Chest was done, which showed multiple thin walled, rounded to irregular, air filled cavities seen in right upper, right middle and left lower lobes, the larger lesion in right middle lobe measuring 5.3 X2.8 X3.2 cm, causing indentation of right heart border. Another large cavitatory lesion was seen in the right lower lobe, with evidence of mild consolidatory changes in the surrounding lung parenchyma. An intensely enhancing lobulated rounded to ovoid lesion measuring 2.1 X1.5 X2.0 cm was noted along the medial wall of this cavity, projecting into its lumen, which showed enhancement, analogous to vascular enhancement in the mediastinum. This lesion was seen to directly communicate with a branch from descending branch of right pulmonary artery. A subcentimeter well defined nodular lesion was seen in the parenchyma of left upper lobe posteriorly, with a small peripheral subsegmental branch of pulmonary artery seen to enter the nodule (Positive feeding vessel sign), s/o Septic embolus in the lung, in view of the already diagnosed Staphylococcal sepsis. A small fluid collection was also seen in right pleural cavity, with thickened enhancing pleura, s/o small empyema, with residual foci of air in pleural cavity from the previous intervention (Fig 2 & 3).
Findings were suggestive of multiple pneumatoceles in both lungs, septic embolus in left upper lobe and pulmonary artery pseudoaneurysm arising from the descending branch of right pulmonary artery.
All the above findings can be explained as sequelae to Methicillin Resistant Staphylococcal sepsis in the infant. Pneumatoceles may have developed due to disseminated bacterimic seeding, while repeated septic emboli to pulmonary arterial tree may have caused destruction and weakening of the wall of vessel, resulting in a saccular outpouching from the vessel wall, forming a pseudoaneurysm1. Though rare, acquired pulmonary artery aneurysms have been reported in adults with necrotising MRSA pneumonia, however, there is only one report in 7 month old infant who underwent successful embolization of peripheral pulmonary artery aneurysm2.Mycotic aneurysms are mostly reported in patients with infective endocarditis, intravenous drug abuse, traumatic injury and sepsis due to Staphylococcus, Streptococcus or Mucormycosis.
In view of the potentially life-threatening nature of this condition, in the probable event of rupture of the pseudoaneurysm, the baby was referred to a higher centre for interventional management. He developed one episode of hemoptysis during his stay and was subsequently planned for high risk coil embolization which maybe a challenge considering the small age of the patient, or lobectomy if it fails.
LEGENDS