Case Report

Different diagnosis have been proposed in radiologic detected thorax masses. They may stem from somewhere else, different of their radiological appearance, as a mass growing from mediastinum into lung, the herniation of hearth atrium secondary to pericardial defects ₁ , the presence of abdominal content into mediastinum through Morgagni or post-traumatic hernia, or the herniation of lung and mediastinal contents due to surgical defects after pneumonectomy ₂ . However, we did not found any previous report of anterior mediastinal herniation from left into right hemithorax secondary to massive malignant pleural effusion. We present a patient with metastatic low grade sarcoma who presented with moderate dyspnea secondary to massive left pleural effusion affecting both hemithorax through anterior mediastinal herniation.

A 36 year-old male without relevant previous clinical conditions referred chronic moderate dyspnea that moved to perform a chest X-ray. He had no history of cough, chest pain or fever, nor anorexia or weight loss. Physical examination revealed a pale but otherwise uncompromised patient with moderate tachypnea. No breath sounds appeared both in left and the lower half of the right hemithorax. Chest X-ray showed an opacified left lung and a compromise of the right lung;

Figure 1

Figure 1: Chest X-ray

CT-scan evidenced inguinal masses and left pleural implants and the presence of pleural effusion in both hemithorax as well (Figure 2).

Figure 2

Figure 2: CT-scan. Pleural masses and left pleural effusion herniated through anterior mediastinum.

Laboratory tests: hemoglobin: 8.68 mmol/l, leukocytes 7.8 10 ⁹ /l, platelets 373 10 ⁹ /l, elemental biochemical parameters were into normal range, PaO2 58 mm Hg (O2 saturation 90%), PaCO2 37 mm Hg, pH 7.46.

An emergency left pleural drainage was performed and both left and right hemithorax effusions disappeared, confirming that apparent right pleural effusion was indeed left fluid herniated through anterior mediastinum.

Pleural effusion was informed as monocytic exudate; no malignant cells were seen. Several biopsies of the pleural mass were performed in an ulterior video-assisted thoracoscopy. Microscopic examination showed a low grade tumor composed by fusiform cells without severe atypia and with less than one mitoses by high power field. Immunohistochemistry was compatible with sarcoma (positive for vimentin; negative for desmin, EMA, cytokeratin, CEA, CAM 5.2 and S-100). Thereafter, an excision biopsy of a palpable but otherwise asymptomatic hard mass in right inguinal fossa was performed. Histological results and immunohistochemistry confirmed the same tumour previously found in left pleura. Tamoxifen and subsequent megestrol acetate were administered with prolonged stabilisation of disease. The patient remains alive five years after diagnosis.

Discussion

Any thorax mass mediastinum may herniated and compromise different structures ₃ . A similar process of thoracic herniation coming from abdomen has been described in tense ascitis ₄ . And so, any expansive process in one hemithorax may potentially protrude and eventually herniate through mediastinum, as well. But we could not found any previous reports of anterior mediastinal herniation secondary to tense pleural effusion. In this patient the tumour adopted an indolent behaviour. This slow and indolent growth may allow a progressive functional adaptation without relevant clinical manifestations. First chest X-ray showed bilateral thorax disease with a suspicion of dextrocardias; only on CT-scan an anterior mediastinal herniation of pleural fluid could be suspected and, eventually, confirmed after left evacuation. Pleural biopsy gave evidence of metastatic low-grade sarcoma. Clinical benefit has been reported for low-grade sarcomas as desmoid tumour with hormone therapy as progestins or tamoxifen ₅ . Palliative chemotherapy achieves an small response rate without any significant benefit on overall survival. In our patient a protracted tumour stabilisation was observed both with tamoxifen and megestrol acetate and he remains alive, so far, five years after diagnosis. As conclusion, mediastinal herniation secondary to tense malignant pleural effusion should be considered as an infrequent differential diagnosis of bilateral pleural effusion.

Correspondence to

Álvaro S. Rubiales Oncology Department Hospital Universitario de Valladolid c/ Ramón y Cajal 3 47011 Valladolid – Spain phone: 34-83-420000 fax: 34-83-257511 e-mail: asrubiales@hotmail.com