A case of pulmonary blastoma showing intrabronchial growth

A case of pulmonary blastoma showing intrabronchial growth

European Journal of Radiology Extra 47 (2003) 73 /77 http://intl.elsevierhealth.com/journals/ejrx A case of pulmonary blastoma showing intrabronchia...

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European Journal of Radiology Extra 47 (2003) 73 /77 http://intl.elsevierhealth.com/journals/ejrx

A case of pulmonary blastoma showing intrabronchial growth Yasushi Itou a,*, Tadashi Kaneko b, Kenichi Yamashita c, Kaname Tomoda a a

Department of Radiology, Kinki Central Hospital, 3-1 Kurumazuka, Itami City, Hyogo 664-8533, Japan b Department of Surgery, Kinki Central Hospital, Itami City, Japan c Department of Pathology, Kinki Central Hospital, Itami City, Japan Received 21 August 2002; received in revised form 20 January 2003; accepted 21 January 2003

Abstract Pulmonary blastoma is a rare primary tumor of the lungs. We present a 33-year-old woman with pulmonary blastoma. The findings on chest radiography, computed tomography and magnetic resonance imaging are discussed. # 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Pulmonary blastoma; Biphasic type; Intrabronchial growth

1. Introduction Pulmonary blastoma is a rare primary malignant neoplasm of the lung that was first reported by Barrett and Barnard in 1945 as ‘embryoma of the lung’ because of its similarity to fetal lung tissue [1]. We present a 33year-old woman with pulmonary blastoma who underwent surgery.

2. Case report A 33-year-old woman was admitted to our hospital with severe dyspnea. The patient had a history of smoking 20 cigarettes per day for 13 years. On admission, laboratory tests showed slight elevation of Creactive protein (1.7 mg/dl, normal B/0.4) and carcinoembryonic antigen (1.4 ng/ml, normal B/5.0). She had already undergone chest radiography because of cough and hemoptysis that had persisted for 6 months before admission and a mass measuring 5 cm had been detected in the right lower lung field. Unenhanced helical computed tomography (CT) had demonstrated a well-circumscribed mass with a smooth margin in the right lower lobe. Prior to admission, she had been

* Corresponding author. Tel.: /81-727-81-3712; fax: /81-727-791567. E-mail address: [email protected] (Y. Itou).

treated for asthma, but no improvement had been achieved. On admission, posteroanterior chest radiography revealed a mass measuring 7 cm in diameter in the right lower lung field (Fig. 1A). Contrast-enhanced helical CT scanning showed a heterogeneously enhanced and well-defined mass in the right lower lobe with an irregular margin and this mass occluded the right lower lobe bronchus (Fig. 1B, C). High-resolution CT (HRCT) showed a thickened bronchovascular bundle adjacent to the mass. There were also multiple centrilobular nodules with a tree-in-bud appearance (Fig. 1D). Magnetic resonance imaging (MRI) was performed for further evaluation of the lung mass. T1-weighted spinecho axial images showed a hypointense mass (Fig. 2A) and T2-weighted turbo spin-echo axial images showed a heterogeneous hyperintense mass (Fig. 2B). Bronchoscopy revealed granulomatous inflammation and obstruction of the right lower lobe bronchus. The patient underwent right lower lobectomy with lymph node dissection. The tumor in the right lower lobe measured 7 /6 /6 cm, was well-encapsulated and showed necrotic foci on the cut surface. The lesion protruded into the right lower lobe bronchus and occluded it. Histologically, polypoid intrabronchial tumor projection into the right was also observed. The intrabronchial tumor measured :/1 cm in diameter (Fig. 3). The mass consisted of glandular elements resembling fetal lung tissue and an immature mesenchymal component. The glandular elements were composed of branching tubules

1571-4675/03/$ - see front matter # 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S1571-4675(03)00090-7

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Fig. 1. (A) Posteroanterior chest radiograph showing a mass measuring 7 cm in diameter in the right lower lung field (arrow). (B) Contrast-enhanced axial chest CT scan and a coronal 2D reconstruction (C) showing a heterogeneously enhanced and well-defined mass with an irregular margin in the right lower lobe (arrow). This mass occluded the right lower lobe bronchus. (D) Multiple centrilobular nodules with a tree-in-bud appearance are seen (arrow) and CT shows a thickened bronchovascular bundle adjacent to the mass.

lined by columnar cells with clear cytoplasm and little nuclear atypia (Fig. 4). The clear cytoplasm was due to abundant glycogen stores, as demonstrated by periodic acid-Schiff (PAS) staining. The glandular cells were immunoreactive for keratin and the mesenchymal cells

were immunoreactive for vimentin. Accordingly, a diagnosis of biphasic pulmonary blastoma was made. The postoperative course was uncomplicated and the patient was doing well at the time writing (3 months after surgery) without any evidence of recurrence.

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Fig. 1 (Continued)

3. Discussion Pulmonary blastoma is a rare primary lung tumor and only :/200 cases have been reported to date. In 1961, Spencer suggested the name ‘pulmonary blastoma’ because of the similarity of this tumor to nephroblastoma [2]. Pulmonary blastoma is estimated to account for :/0.5% of all pulmonary neoplasms [3]. This tumor is composed of immature epithelium that mimics fetal lung tissue and/or mesenchymal tissue. Pathologically, pulmonary blastoma is divided into three types, which are well-differentiated fetal adenocarcinoma (WDFA), biphasic pulmonary blastoma and pleuropulmonary blastoma. WDFA consists solely of immature epithelium mimicking that seen in the fetal lung [4]. Biphasic pulmonary blastoma consists of immature epithelium and a mesenchymal component [4], while pleuropulmonary blastoma consists solely of immature mesenchyme [5]. The mean age of patients with WDFA and biphasic pulmonary blastoma is 35 years (range: 0.66 / 72 years) and the peak incidence is in the third to fourth decades [4]. WDFA is often a smaller tumor than biphasic pulmonary blastoma and its prognosis is better than that of the latter [4]. Statistical analysis of survival data has shown significantly better survival of WDFA patients over those with biphasic pulmonary blastoma [5]. Pleuropulmonary blastoma exclusively occurs in children B/15 years of age. The major symptoms include cough, chest pain and hemoptysis [4]. However, :/40%

Fig. 2. (A) T1-weighted spin-echo axial MRI (TR/TE: 866.5/30) shows a hypointense mass. (B) T2-weighted turbo spin-echo axial MRI (TR/ TE: 3492.9/90) shows a heterogeneous hyperintense mass.

of patients are asymptomatic and their tumors are found by routine chest radiography [4]. Pulmonary blastoma is usually a well-circumscribed tumor that is located at the

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Fig. 3. Histologically, the tumor protruded into the right lower lobe bronchus (H&E, /6).

Fig. 4. Histopathological examination shows a mixture of glandular elements resembling fetal pulmonary tissue and an immature mesenchymal component. The glandular elements consist of branching tubules lined by columnar cells with a clear cytoplasm and little nuclear atypia (H&E, / 100).

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periphery of the lung [3,4] and :/30% of these tumors show intrabronchial growth, as was observed in our case [3,4]. Since pulmonary blastoma is often difficult to diagnose by cytologic studies, the definitive diagnosis is usually made by pathological examination of the resected specimen [4]. The CT features of pulmonary blastoma have been reported to include a well-circumscribed mass with a smooth margin that contains areas of necrosis and hemorrhage [6 /8]. In this case, CT showed a well-circumscribed mass that had an irregular margin and multiple centrilobular nodules with a treein-bud appearance and this mass occluded the right lower lobe bronchus. Centrilobular branching structures on HRCT indicate the presence of interstitial thickening surrounding the centrilobular artery (peribronchiolar disease, perilymphatic disease, perivascular disease) or dilatation and filling of the centrilobular bronchiole. In this case, as the mass showed intrabronchial growth into the right lower lobe bronchus, the finding of centrilobular nodules may reflect the tumor growth into the bronchiole. On MRI, pulmonary blastoma has been reported to be visualized as a heterogeneous hypointense mass on T1-weighted images and as heterogeneous hyperintense mass on T2-weighted images, reflecting the presence of necrosis and hemorrhage, similar to the

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findings in this case [6,9]. In conclusion, we presented a case of pulmonary blastoma showing intrabronchial growth.

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