Mediastinal hemangioma: Masquerading as pleural effusion.

We present a rare case of mediastinal hemangioma in a 4-year-old child. The child presented with cough and fever and the chest radiograph revealed right pleural effusion. On further work-up with chest computed tomography mediastinal cystic mass occupying the right hemithorax was identified. The cystic mass was resected completely through a right thoracotomy. Histopathological examination established the final diagnosis of mediastinal capillary hemangioma.

INTRODUCTION

Hemangioma of the mediastinum are rare benign vascular tumors, with incidence of less than 0.5% among all mediastinal masses.[1234] Anterior mediastinal hemangiomas are reported to be slightly more common than in the posterior mediastinum. They are pathologically either cavernous or capillary hemangiomas.[1] Mediastinal hemangioma in a child, presenting with pleural effusion has not been reported earlier to the best of our knowledge. We report a case of anterior mediastinal capillary hemangioma manifesting as pleural effusion, successfully managed by surgical excision.

CASE REPORT

A 4-year-old male child presented to the out-patient department with the complaints of fever and cough of 3 months duration with respiratory distress of recent onset. Chest radiograph showed features of the right sided loculated pleural effusion [Figure 1]. Ultrasonography of the chest showed moderate pleural effusion with multiple thick irregular septa with low level internal echoes.

Figure 1

Chest radiograph showing right hemithorax opacity indicative of pleural effusion

On needle thoracocentesis straw colored fluid was aspirated. Evaluation of pleural fluid revealed, cell count of 1,200/cu mm, proteins of 498 mg/dl and sugar of 59 mg/dl and no bacteria including acid fast bacillus was identified. Computed tomography (CT) of the chest revealed multiseptated lesion occupying lower 3/4th of the right hemithorax [Figure 2].

Figure 2

Computed tomography of the chest revealed multiseptated cystic mass. Arising from the anterior mediastinum occupying 3/4th of the right hemithorax

An inter-costal drain (ICD) tube was placed in the right hemithorax as the child had respiratory distress. Post-procedure evaluation with chest radiograph and an ultrasonogram of thorax revealed a partially collapsed mediastinal mass lesion with residual cystic lesion, hence planned for surgical excision. Initially, video assisted thoracic surgery was attempted and converted to the right posterolateral thoracotomy through the 5th inter-costal space in view of poor visibility and obscure anatomy. The operative findings included, single well encapsulated cystic lesion with multiple loculations containing serosanguinous fluid. There were inflammatory adhesions to surrounding structures including lungs, parietal pleura and pericardium. The lesion was compressing middle and lower lobes with no invasion to surrounding structures. The cyst was excised in-to and subjected to histopathological examination. Post-operative recovery was uneventful. Post-operative chest radiograph showed well expanded lungs, ICD tube removed on the post-operative day 3 and the child was discharged on the next day.

Gross pathological examination of the tumor showed well encapsulated cystic lesion with multiple septations measuring 10 × 10 × 8 cm [Figure 3]. Microscopic examination revealed vascular spaces lined by flat endothelial cells; moderate intervening fibrocollagenous stroma along with few inflammatory cells [Figure 4]. These findings were diagnostic of capillary hemangioma. There was no evidence of cellular atypia or mitotic figures indicating that it was a completely benign lesion.

Figure 3

Excised specimen of multiseptated well encapsulated cystic mediastinal mass measuring 10 × 10 × 8 cm

Figure 4

Vascular spaces lined by flat endothelial cells with moderate intervening fibrocollagenous stroma along with few inflammatory cells (H and E, ×400)

Patient was followed-up in the out-patient department at 1 week, 1 month and 6 months and 1 year post-operatively and was doing well. The chest radiograph taken at 6 month follow-up visit was normal.

DISCUSSION

Mediastinal hemangiomas comprise only 2-3% of all the hemangiomas in children.[56] Only 125 documented cases of mediastinal hemangiomas had been reported in the literature until date.[7] Various types have been described including hemangiomas, hemangiopericytomas and epitheloid hemangioendotheliomas (previously called intravascular bronchioloalveolar tumors).[89] Almost 50% of all patients with mediastinal hemangioma are asymptomatic.[4] The remainder present with non-specific symptoms, such as cough, chest pain, fever and dyspnea, due to compression or adhesion to adjacent structures. Dysphagia, superior vena cava syndrome and neurologic symptoms by intraspinal tumor extension are rare complications.[1011]

Mediastinal hemangiomas appear as sharply marginated, circular or lobular masses on chest radiographs.[12] However, the chest radiograph of the patient in our study showed diffuse opacity involving the right hemithorax without any calcifications or phleboliths mimicking pleural effusion. Phleboliths are radiologically characteristic of hemangioma, but they are only visible in 10% of all cases.[13] Punctate calcification can be seen in 21% cases.[12]

Contrast-enhanced computed tomography chest is useful in evaluating the origin and extent of the lesions. An attempt was made in a study by McAdams et al. to retrospectively characterize the pattern of enhancement of mediastinal hemangioma on CT images after the administration of a contrast material, but no specific radiologic findings were identified to make a definitive diagnosis.[12] However, chest CT is useful in evaluating the extent of lesions to plan operative intervention. Furthermore, angiography doesn’t always reveal findings suggestive of a vascular tumor as reported by Ishii et al.[14] Magnetic resonance imaging is thought to be useful in the diagnosis of mediastinal hemangioma.[1415] However, Marchevsky and Kaneko reported that no pre-operative investigations were diagnostic prior to biopsy.[8] Chest CT of patient in our study was not conclusive of mediastinal hemangioma. Pre-operative diagnosis is difficult despite the modern imaging modalities. High index of suspicion and biopsy of lesion will help in the diagnosis.

Management of mediastinal hemangiomas is usually by surgical excision. Complete excision is recommended when feasible as performed in the present case. However, for cases in which complete resection is difficult due to local extension and firm adhesion to a vital structure, radiation therapy has been reported to be effective in reducing the size of hemangiomas. Cohen et al. proposed a subtotal resection to be the best therapeutic option in such cases and have reported that five of their six patients who had undergone a subtotal resection had no evidence of tumor growth from the residual tumor.[4] Medical management of mediastinal hemangiomas is an option when a definitive diagnosis has been made. Drugs used include corticosteroids, interferon-alfa, prednisone and propranolol.

Mediastinal hemangioamas should be considered as an important differential diagnosis of mediastinal masses, even though these are rare. Suspicion of this diagnosis prior to surgery will likely alter the approach and management and can greatly reduce the risk of hemorrhage.