Clinical Meetings at RH Year 2001

2001 - A Lady with Mediastinal Mass

Dr. LAM Wai Kei, Dr. CHOO Kah Lin, Department of Medicine & Department of Diagnostic Radiology, North District Hospital

Case History
A 47-year-old lady was found collapsed at home. She had a history of weight loss and an episode of "haematemesis" 6 months ago. During the week prior to admission, she had also developed haemoptysis. On arrival in the accident and emergency department (AED), she was in hypovolaemic shock requiring transfusion of unmatched blood. Because of impending respiratory arrest, this lady was intubated and started on dopamine infusion. She was then transferred to the intensive care unit (lCU). Her blood pressure was stabilized at 153/77 mmHg. Clinical examination revealed clubbing of fingers and toes. She was febrile with bilateral inspiratory coarse crackles on chest auscultation. No melaena was found on rectal examination. There was no cervical lymphadenopathy or goitre. Abdominal and cardiovascular examination was unremarkable. Blood stained secretion was aspirated from the endotracheal tube. The lady was profoundly anaemic (Hb = 5.5 g/dl). There was leucocytosis (WBC = 34.2 x 109/L) with neutrophilia (90.1%). The clotting profile was mildly deranged (PT 14.4 sec, APTT 33.2 sec, lNR 1.3). Albumin was low at 28 g/dl. Otherwise electrolytes, renal and liver function was normal. The initial respiratory and metabolic acidosis was corrected soon after lCU admission. Oxygenation was maintained with a FiO2 of 0.4.

Chest radiographs (Fig. 1a and 1b) showed an anterior mediastinal mass with an air crescent sign and consolidation over right lower lobe. Bed side bronchoscopy revealed blood clots in trachea and in lingular bronchus. There was no active bleeding. Tracheal aspirate grew Enterobacter cloacae. Acid fast bacilli smear was negative. Cytology showed acute inflammatory exudate. There was no significant growth on blood culture and urine culture. Computed tomography (CT) of thorax (Fig. 2a, 2b and 2c) showed a large anterior mediastinal mass with calcification and heterogeneous attenuation including fat and air densities.





Fever and leucocytosis resolved on antibiotics. No further haemoptysis was noted during the lCU stay. This lady was extubated on Day 6. However, she became emotionally unstable and refused further blood taking, intravenous injections or CT guide biopsy. She was discharged to the general ward with Hb of 10.6 g/dL , WBC 10.6 x 109/L, SaO2 95% on 2L1minute oxygen and blood pressure of 119/66 mmHg. Six hours later, this lady developed sudden cardiac arrest preceded by massive haemoptysis. Efforts at resuscitation were failed.

Post-mortem
A 9 x 6.5 x 4 cm mass was found in the anterior mediastinum attached to left upper lobe of the lung. Section of this mass showed numerous hair, yellowish fatty area and cystic spaces. (Fig. 3) Left upper lobe bronchus contained some blood. Left pleural effusion was present. Alimentary and genitourinary systems were normal. Genital organs were unremarkable. On microscopic examination (Fig. 4a and 4b) the mass consisted of an admixture of mature squamous epithelium, cuetaneous appendages, respiratory type epithelium and mature adipose tissue. There were no immature elements. Left lung showed bronchopneumonic changes. Central nervous system was unremarkable. Findings were compatible with mature mediastinal cystic teratoma and left lung bronchopneumonia.





Discussion
Wereported a case of benign teratoma causing fatal haemoptysis initially presented as shock and a mediastinal mass. Mediastinal masses have diverse etiologies (Table 1). Majority (>75%) of mediastinal masses in adults are benign, whereas 50% of them are malignant in children.! Differential diagnosis of non-vascular mass lesions in mediastinum can be narrowed by their location in the mediastinum (Table 2)? A teratoma is a germ cell tumor composed of tissues arising from more than one of the three embryonic germ cell layers (Figure 5): Ectoderm (e.g. teeth, skin, hair), mesoderm (e.g. cartilage and bone) and endoderm (e.g. bronchial, intestinal and pancreatic tissue).3 Teratoma can be further divided into mature teratoma, immature teratoma and malignant teratoma (synonym: teratocarcinoma). A mature teratoma consisted of benign, histologically well differentiated cells. Immature teratoma contains fetal tissue which has the propensity to recur or metastasize. Malignant teratoma is any teratoma containing a focus of carcinoma, most commonly adenocarcinoma, squamous cell carcinoma, sarcoma or malignant germ cell tumor.4 Malignant teratoma is less likely to contain well differentiated structures like hair and tooth.1







Mature teratoma is the most common primary germ cell tumor in the mediastinum. It has a male to female occurrence ratio of 1:1.5When symptomatic, the duration of symptoms could be from 1 week to 18 years.! Common symptoms include chest pain, dyspnoea, cough, fever, and blood stained sputum. Clubbing is a clinical sign. Mediastinal teratoma may be asymptomatic and incidentally found as a mediastinal mass on chest radiographs. Mature teratoma can also masqueraded as a multiloculated pleural effusion.6

On computerized tomography (CT), mature teratomas are well-defined, rounded or lobulated masses composed of cystic and solid components. Calcifications are common. Fat densities are present in 50% of cases. Cystic lesions without fat or calcium were seen in 15% of tumors. In fact any combinations of soft-tissue, fluid, fat or calcium attenuation is possible. Sometimes a fat-fluid level could be seen. Fat-fluid levels are highly specific for the diagnosis of mature mediastinal teratoma.7Presence of recognizable bone and teeth are classical but rare. Upward drift of tumor internal components during the course of a computed tomography examination is an interesting reported feature.8

Presence of macroscopic cysts is a sign of benignancy. In a series of 106 excised mediastinal teratomas, 86 were mature teratomas. 80 (93%) of the mature teratomas were cystic. For the 20 malignant mediastinal teratomas, all (100%) of them were predominantly solid.

Rupture is a unique complication of mature teratoma. Up to 36% of all mediastinal teratomas ruptured, most frequently into the lung and bronchial tree, followed by the pleural space, pericardial space and great vessels9. It can be sub-acute or acute in onset. Cases of teratoma rupture causing life threatening spontaneous pneumothorax, haemothorax1° or cardiac tamponade11 were reported in the literature. Pneumonia and lung abscess develop if contents of teratoma are spilled into lung parenchyma. A rupture into bronchus will cause trichoptysis and haemoptysis. Rupture into pleural space will result in pleural effusion or pneumonthorax. Rupture into pericardial space will lead to pericardial effusion or acute cardiac tamponade (Fig. 6). Effusions may be caused by a direct spillage of internal components of the tumor or a pleural! pericardial inflammatory reaction to extravasated tumor contents.



In contrast to other solid tumors, teratoma has unique mechanisms for rupture. Rupture can occur because of autolysis by pancreatic digestive enzymes, chemical inflammation inflicted by the sebaceous material, rapid tumor growth causing necrosis, or secondary infections.9 Malignant teratomas are not prone to rupture as they are predominantly solid and they are less likely to contain well differentiate tissue like pancreatic cells. Radiological signs of teratoma rupture include lung consolidation, pleural or pericardial effusion. CT can be used to differentiate ruptured and unruptured teratomas. Heterogenous densities on CT thorax in a single compartment in the tumor is a sign of teratoma rupture, as contents of compartment are mixed together with a secondary inflammatory reaction to extravasated contents (Table 3).12 In our case, air in the tumor signified rupture of teratoma into the bronchus.



Massive haemoptysis in patient with mature mediastinal teratoma has been rarely reported. Three paediatric cases were found. The cause of bleeding were ulceration of gastric mucosa into lung parancyma13, systemic to pulmonary artery shuntingl4, and presence of yolk sac elements within the tumor associated with myelofibrosisl5. Only one adult case of mediastinal teratoma causing massive hemoptysis has been reported in the literature. That patient survived.16 In our lady, it was likely that the massive haemoptysis which led to her decease was the result of rupture of the teratoma directly into the left upper lobe bronchus and flooded her airways. This is supported by the appearance of air densities within the heterogeneous mass and presence of blood in the left upper lobe bronchus.

Management of mature teratoma is early surgical resection. Teratomas are frequently so firmly adhered to thymus and pericardium that they need to be excised together with the tumor. Pulmonary segmental or lobar resection may be necessary when pulmonary complications has occurred.1 Delayed surgery will increase difficulty for complete excision. Surgery is otherwise curative and prognosis is good. Video thoracoscopic resection has been successful. 17 Transthoracic needle aspiration was reported to be useful in the aspiration of cystic contents of a large teratoma to relieve respiratory distress before surgical excision.18

References

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