Introduction
A pulmonary arterio-venous malformation (PAVM) is a rare condition which is predominantly a congenital malformation known as Osler-Weber-Rendu, also known as Hereditary Haemorrhagic Telangiectesia (HHT) (Hayashi et al., 2012). However, there is yet to be cases on spontaneously resolved acquired inflammatory AVM being reported in the literature. We are the first to report an acquired inflammatory pulmonary AVM which resolved spontaneously without any medical or surgical treatment.

1 Case
A 62 years old gentleman presented with a few days history of haemoptysis and increased shortness of breath after aspirating a water soluble contrast for investigation of dysphagia. A Computed Tomography (CT) of chest was performed and it revealed a right lower lobe vascular lesion with surrounding inflammation (Figure 1). A further Computed Tomography Pulmonary Angiogram (CTPA) was obtained and confirmed the suspicion of arterio-venous malformation (AVM) (Figure 2). A multidisciplinary team was convened and the decision for surgical resection of the lesion was planned. A pre-operative CT scan was performed two months after the diagnosis was made. In contrast to the initial CT scan, the vascular lesion has surprisingly completely resolved and only a focal inflammation was left in-situ.

Figure 1 The above shows sagittal view of non contrast (prior) and contrast enhanced (posterior) CT scan of the chest. Both show pulmonary AVM in the right lower lobe

Figure 2 The images above shows complete resolution of the PAVM. Only a subtle residual fibrosis of lung tissue was seen at the right lower lobe

 
The patient was followed up in the out-patient department and his symptoms have completely resolved. He was thus discharged from the cardiothoracic department.

2 Discussion
Pulmonary arterio-venous malformation (PAVM) is a rare vascular lesion which accounts for 2-3 per 100 000 population (Hayashi et al., 2012; Dewar and Schonell, 1966). PAVM is classified into primary and secondary PAVM, also known as acquired pulmonary AVM.

The aetiology of primary vascular abnormality is unknown but it is strongly associated with Hereditary Haemorrhagic Telangiectasia, which accounts for almost 70% of the incidence of PAVM (Ghersin et al., 2010). Secondary PAVMs are rare. Reported causes include chest trauma, long standing hepatic cirrhosis, metastatic lung carcinoma ad amyloidosis (Kurshid and Downie, 2002; Prager et al., 1983; Symbas et al., 1980; Kamei et al., 1989; Pierce et al., 1959).

Majority of the patient with PAVM are asymptomatic. The discovery of PAVM is usually through routine chest x-ray (Kurshid and Downie, 2002). The classical triad of presentation is dyspnea, cyanosis and clubbing (Prager et al., 1983). In patients with Osler-Weber-Rendu, presentation such as recurrent epistaxis and cardiac murmur may also be present (Dewar and Schonell, 1966). Chest x-ray is a valuable tool in detecting the vascular lesion. It is also commonly used for clinical follow up (Kurshid and Downie, 2002; Sluiter-Eringa et al., 1969) Computed Tomography (CT) Scan, especially a contrast enhanced CT scan is good in defining the vascular lesion (Kurshid and Downie, 2002).

There have been no reported cases of spontaneously resolved inflammatory AVM in the literature. We are the first team to report this. From this experience, we suggest that in a spontaneously occurring inflammatory PAVM, conservative management should be adapted in the first instance instead of putting patients through surgery to begin with. Close monitoring of the condition should be initiated to confirm resolution. Surgical excision and endovascular embolization has been the treatment of choice for PAVM (Hayashi et al., 2012; Kurshid and Downie, 2002). However, there has been no similar case being reported. Hence, it is difficult to ascertain the best way of management forward. More relevant cases should be reported to compare management options and prognosis.

3 Conclusion
Even though the treatment for arterio-venous malformation is surgical resection, the approach for an inflammatory AVM can be taken conservatively because it can spontaneously resolve.

However, close monitoring is essential to ensure complete resolution.

If there is no complete resolution, either surgical or endovascular intervention might be needed.

Authors’ contribution
Wong KB – main author; Chan SA – contribute in writing the discussion; Abid Q – Final approval of the script.

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