CASE REPORT An unusual congenital pulmonary •arterlo-venous fistula Abstract JQ Davies S Andronikou J Lawrenson Pulmonary arteriovenous malformations (AVM) are rare causes of a cardiac murmur in the paediatric population. They are caused by abnormal communications betvveen pulmonary arteries and veins that are most common ly congenital in nature. Although these lesions are fairly uncommon, they are an important differential diagnosis to consider in patients with common pulmonary problems such as hypoxaemia and/or a pu Imonary nodule(s). This report illustrates the clinical presentation, radiological features and pathological findings in an eight- month-old boy. Keywords Fistula" arteriovenous" congenital" trisorny 21 Departments of Paediatric Pathology, Radiology and Cardiology Red Cross War MemorIal Children's HospItal Rondebosch, Cape Town 39 SA JOURNAL OF RADIOLOGY· February 2001 Case report An eight-month-old male patient with Down's syndrome was referred for cardiac catheterisation at the Red Cross Children's Hospital. He had signs of a left-to-right shunt with bounding pulses and a machinery murmur at the upper left sternal border. Both on clini- cal grounds and on echocardiographic examination it was felt that he had a PDA. Cardiac catheterisation (with a view to possible coil embolisation) was performed. At catheterisation, a duct was seen but was noted to be small. The larger feeding vessel was noted during the same angiogram. A contrast CT scan confirmed that there was a pulmonary arteriovenous malformation occupying the lower lobe of the left lung (Figures I, 2 and 3). An artery originating from slice above Figure I- demonstrates vascular malformation draining into the left atrium via a large draining veIn (arrow) topage40 An unusual congenital pulrnonary arterio-venous fistula frompage39 patic cirrhosis" and bron- chiectasis' and should always be considered in the man- agement of such patients. PAVMs occur twice as often in women as in men, but there is a male pre- dominance in new-borns (as in the index case), where symptoms may vary from being totally absent to severe with cyanosis, congestive heart failure and even fulminant respiratory failure." Around 10% of cases ofPAVM are identified in infancy or childhood, Figure 3: A 3D reconstruction elegantly demonstrates the group of abnormal vessels (arrow) and its arter/al blood supply from the descending thoracic aorta the descending aorta, just above the diaphragm, supplied this lesion, which was seen to drain into the left atrium. The feeder vessel was ligated and a left lower lobe lobectomy was per- formed. This showed a vascular mal- formation composed of large, dilated interconnected vessels, many of them histologically resembling arterialised veins (Figure 4). Discussion Since their first description at au- topsy in 1897,1 these lesions have also been called pulmonary arteriovenous "fistulae", pulmonary arteriovenous "aneurysms", "hemangiomas" of the lung, "cavernous angiomas" of the lung, pulmonary "telangiectases" and pulmonary arteriovenous malforma- tions.? The term "pulmonary arterio- venous malformations" (PAVM) ap- pears to be most Widely accepted in modern literature.' Although most commonly a con- genital abnormality, abnormal com- munications between blood vessels of the lung may also be found in a vari- ety of acquired conditions, such as he- an inherited disorder of autosomal dominant inheritance, characterised by arteriovenous malformations of the skin, mucous membranes and visceral organs.' Patients with a PAVM should therefore be screened for this syn- drome. There were no such features in our patient, despite an extensive search that included contrast CT scan of the brain. The classic clinical triad of dysp- noea, clubbing and cyanosis is rarely seen, with adult patients presenting most commonly with epistaxis, re- flecting the strong association with HHT. Dyspnoea and haemoptysis are also common symptoms and in half of cases a bruit or murmur can be heard, most audible during inspira- tion.' Our patient had a particularly loud murmur that was clinically thought to be a large PDA. PAVM usually occurs in the lower lobes and is solitary in 75% of cases." It can be classified as either simple or complex. The simple type (80-90% of cases) is de- fined as hav- ing a single feeding seg- mental artery and a single draining vein. The rest are complex, with two or more feeding arteries or draining veins." In the majority of patients ( about 95%), the AVMs are supplied by pul- monary arteries. AVMs are supplied by systemic arteries less frequently." Figure 4: Pulmonary AVM - an interconnected arrangement of thick-walled vascular channels (arrow) within the lung parenchyma (H&E x 4) with a peak incidence occurring in the fourth to sixth decades of life. Ap- proximately 70% of the cases of PAVM are associated with hereditary haemorrhagic telangiectasia (HHT), 40 SA JOURNAL OF RADIOLOGY- February 2001 topage41 An unusual congenital pt.rfrriorrarv arterio-venous fistu la from page 40 Such AVMs need to be differentiated from true sequestrations. Drainage is usually to the left atrium, but anoma- lous drainage to the inferior vena cava or innominate veins has been re- ported. 2, II Pathological examination shows that PAVMs are similar to AVMs oc- curring elsewhere in the body. The malformations may have one of three typical appearances: (1) a large, sin- gle sac, (2) a plexiform mass of dilated vascular channels, or (3) a dilated and often tortuous direct communication between artery and vein.9,11 Mural thrombi or calcifications are also oc- casionally seen.' The classic roentgenographic ap- pearance of a PAVM is that of a round or oval mass of uniform density, fre- quently lobulated but sharply defined and more commonly in the lower lobes.' Although uncommon, multi- ple lesions may be identified." Soli- tary PAVMs will often show feeding vessels on chest radiography, with the artery radiating from the hilus and the vein deviating towards the left atrium." Despite advances in diagnostic techniques mentioned thus far, con- trast pulmonary angiography remains the gold standard in the diagnosis of PAVM. Contrast echocardiography, computed tomography, radionuclide perfusion lung scanning, pulmonary angiography and magnetic resonance imaging are all further useful modalities.' Treatment depends on the clini- cal symptoms, signs and size of the lesion and includes surgical resection, embolisation therapy or hormonal manipulation. In summary, therefore, PAVMs are uncommon paediatric problems, but should be considered in patients with (1) one or more pulmonary nodules, (2) mucocutaneous telangiectases and (3) unexplained clinical findings such as dyspnoea, haemoptysis, hypoxae- mia, a machinery heart murmur, club- bing or cyanosis. References I. Churn T. Multiple aneurysms of the pulmonary artery. BM] 1897; 1: 1223-1225. 2. Slogan, RD, Coolly RN. Congenital pulmonary arteriovenous aneurysm. A]R 1953; 70: 183-210. 3. Gossage JR, Ghassan K, Pulmonary arteriovenous malformations: A state of the art review. Am ] Respir Crit Care Med 1998; 158 (2): 643-661. 4. El Gamal M, Stoker JB, Spiers EM, Whitaker W. Cyanosis complicating hepatic cirrhosis: Report of a case due to multiple fulmonary arteriovenous fistulas, Am ] Cardia 1970; 25: 490-494. 5, Liebow AA, Hales MR, Lindskog GE. Enlargement of the bronchial arteries and their anastomoses with the pulmonary arteries in bronchiectasis. Am] Patho11949; 25: 211-231. 6, Allen SW, Whitfield JM, Clarke DR et al. Pulmonary arteriovenous malformation in the newborn: A familial case. Pediair Cardiol1993; 14: 58-61. 7. Vase P, Holm M, Arendrup H. Pulmonary arteriovenous fistulas in hereditary hemorrhagic telangiectasia. Acta Med Scand 1985; 218: 105- 109, 8. Bosher LH Jr, Blake DA, Byrd BR. An analysis of the pathologic anatomy of pulmonary arteriovenous aneurysms with particular reference to the applicability of local excision. Surgery 1959; 45: 91-104. 9, White RI, Mitchell SE, Barth KH, Kaufman S et al. Angioarchitecture of pulmonary arteriovenous malformations: An important consideration before embolotherapy. AfR 1983; 140: 681-686. 10. Dines DE, Arms RA, Bernatz PE, Gomes MR. Pulmonary arteriovenous fistulas, Mayo Clin Proc 1974; 49: 460-465. Il. Anabtawi IN, Ellison RG, Ellison LT.Pulmonary arteriovenous aneurysms and fistulas: Anatomical variations, embryology and classification. Ann ThoracSurg 1965; J: 277-285, 12. Hales MR. Multiple small arteriovenous fistulae of the lungs. Am] Patho11956; 32: 927-943. 13. Dines DE, Seward JB, Bernatz PE. Pulmonary arteriovenous fistula. Mayo Clin Proe 1983; 58: 176-181. from page 21 A review of paediatric abciorninal rnasscs Conclusion Any abdominal organ may develop a mass. The spectrum of clinical pres- entations is broad and assessment of the child with an abdominal mass may, at first, seem daunting. A small pro- portion of entities account for the vast majority of cases and a knowledge of the statistical distribution, age and sex of the patient, clinical presentation (notably pain or pyrexia) and imaging characteristics (especially solid vs cystic nature) allows the formulation of a focused differential diagnosis. Ultrasound has proved to be an invaluable tool in the assessment of paediatric abdominal masses because it is safe and efficacious, but the diag- nostic capabilities of CT may often outweigh the radiation risk, especially in the older child. MRI is increasingly more useful and may be the modality of choice in the future. References I. Stevenson RJ. Abdominal masses. Surg Clin NAm, 1985; 65 (5): 1481-1504. 2. Hilton SvW, Edwards OK, Practical paediatric radiology. Philadelphia: WB Saunders Co, 1994: 357-387. 41 SA JOURNAL OF RADIOLOGY· February 2001 3. Schwartz MZ, Shaul DB. Abdominal masses in the new-born. Paedr Rev, 1989; 11 (6): 172-179. 4. Brodeur A, Brodeur G, Abdominal masses in children: Neuroblastoma, Wilm's tumour and other considerations. Paedr Rev, 1991; 12 (7): 196-207. 5. Wedge JW, Grosfeld JL, Smith JP. Abdominal masses in the new-born: 63 cases. J of Urology, 1971; J 06: 770-775. 6. Swischuk LE, Hayden CK. Abdominal masses in children, Paed Clin NAm, 1985; 32 (5): 1281-1298. 7, Hartman GE, Shochat SJ. Abdominal mass lesions in the new-born: Diagnosis and treatment. Clin Perinat, 1989; 16 (I): 123- 135, 8, Merten OF, Kirks DR, Diagnostic imaging of paediatric abdominal masses. Paed Clin NAm, 1985; 32 (6): 1397-1425.