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Pulmonary Blastoma
Gustad B Daver*, Girish D Bakhshi**, Arun S Patil***, Aftab S Shaikh****,
Nitin P Mokashi****, Yogesh S Puri****, Harveshp D Mogal****
 

Pulmonary blastoma is a rare lung neoplasm of disputed histogenesis and variable biologic behaviour. Typical cases contain both epithelial and mesenchymal tissues, and a variety of patterns of differentiation have been described. While expression of oncofoetal antigens in these tumours have been noted rarely, a coexisting component of germ cell tumour has been rarely seen. We describe the clinical and pathologic features of an 18 year old male who was diagnosed on histopathology as a case of pulmonary blastoma having histologic areas of yolk sac tumour.

Introduction
Pulmonary blastoma is a rare primary malignancy of the lung originating from multipotential pulmonary blastoma. It represents less than 1% of all lung cancers.1 It consists of immature mesenchymal and epithelial structures that can mimic the structure of the embryonic lung. The pathologic features of this disease is microscopically divided in two classes: 1) lesions composed solely of malignant gland of embryonic appearance (WDFA: Well-Differentiated Foetal Adenocarcinomas), and 2) lesions with biphasic appearance, containing both neoplastic glands and either adult sarcomatous or embryonic mesenchyme.2

There are no specific clinical features that differentiate this tumour from the more common lung neoplasms.

Case Report
We present a case of 18 year old male who presented to us with pain in the right side of chest, dry cough, occasional fever and breathlessness since one month. Clinical examination revealed decreased air entry on right side. X-ray chest showed right side hydropneumothorax with pneumonitis. Diagnostic tapping showed haemorrhagic fluid with proteins 4.3 gms% and sugar 123 mgs%. Fluid Adenosine deaminase (ADA) was normal and Montoux test was negative which ruled out tuberculosis. CT scan of thorax revealed lobulated cystic lesion in the upper lobe of right lung favouring a diagnosis of complicated hydatid cyst (Fig. 1). Patient was worked up for surgery. Intra-operative findings showed mass lesion occupying the upper lobe of right lung containing haemorrhagic and necrotic material. Complete evacuation of the mass was done and sent for histopathology. Thorax was closed after putting an Intercostal drain. Post-operative course was uneventful. Intercostal drain was removed on 8th post operative day and suture removal was done on 10th post operative day. Histopathology of the specimen showed pulmonary blastoma with yolk sac differentiation i.e. glomeruloid bodies with PAS positive hyaline globules with areas of necrosis (Fig. 2). Patient was given chemotherapy post-operatively. Follow-up of three months has shown patient to be symptom and disease free.

Discussion
Pulmonary blastoma is a rare primary malignancy of the lung originating from multipotential pulmonary blastoma. Pulmonary tumours of embryonic origin are rare, and pulmonary blastomas are probably the most uncommon. A pulmonary blastoma is a rare malignancy, representing less than 1% of all lung cancers.1

This tumour mimics the embryonic elements of the lung in early foetal development. A pulmonary blastoma should not be confused with the pleuropulmonary blastoma of childhood, which is analogous to a Wilm's tumour of the lung in which there is no recognizable neoplastic epithelium. The 2 types of pulmonary blastoma are biphasic and foetal, also known as well differentiated foetal adenocarcinoma.2 Biphasic pulmonary blastomas contain both neoplastic glandular tissue and either adult sarcomatous or embryonic mesenchymal tissue3 whereas a well-differentiated foetal adenocarcinoma contains solely malignant glands of embryonic appearance. Several stage-specific embryonic antigens have been observed in the neoplastic cells of pulmonary blastomas, supporting an embryonal nature.4
Fig. 1 : CT scan showing right lung blastoma mimicking complicated hydatid cyst. Fig. 2 : Histology slide of Pulmonary Blastoma showing undifferentiated cells with arrow marked glomeruloid body (10X).

However, because of the existence of composite cases showing features of pulmonary blastoma and carcinosarcoma and because of sporadic cases displaying aberrant types of differentiation in pulmonary blastomas, including melanocytic and yolk sac elements, origin from a pluripotential stem cell is currently favoured by most investigators.5

Biphasic blastomas occur at any age, with the mean age at diagnosis being 35 to 40 years.6 In 80% of patients, there is a history of tobacco use, suggesting that the same agents that are thought to have a role in the pathogenesis of bronchogenic carcinomas may also be involved in the development of pulmonary blastomas.6 Approximately 25% to 40% of patients are asymptomatic at presentation, with incidental diagnosis by chest radiography. Haemoptysis and cough are the most common symptoms in patients with tumours affecting the bronchi, whereas chest pain is common when the pleura is involved.6 Our patient was an 18 year old male who presented with chest pain and cough.

Pleural effusion occur occasionally. Radiography shows a well-demarcated peripheral lesion encapsulated by compressing or atelectatic lung tissue. Some lesions tend to be lobulated and cavitated. The lesions are large, from 2.5 to 25 cm, and grow rapidly; frequently, haemorrhage and necrosis are noted on gross pathologic specimens.6 The prognosis is worse with the biphasic blastoma than with the foetal type because of the high incidence of metastasis in the former.6

Overall, survival is 25% at 1 year and 16% at 5 years. Factors that indicate a poor prognosis are tumour recurrence, metastases at initial presentation, tumour greater than 5 cm, and lymph node metastases.6 Distant metastases are often noted in the liver, central nervous system, mediastinum, and bones. Immunohistochemically, the epithelial elements in blastomas react positively for keratin, carcinoembryonic antigen, epithelial membrane antigen, and milk fat globulin. Immunoreactivity for vimentin is generally seen in the nonepithelial component. The histopathologic differential diagnosis of pulmonary blastomas of the biphasic type in which the tumour shows a prominent spindle mesenchymal component is carcinosarcoma. Some investigators believe that these tumours represent a spectrum of growth patterns, and they regard blastomas as variants of carcinosarcomas.7

Therapy for biphasic blastomas includes surgical resection with adjuvant radiotherapy and combination chemotherapy with cisplatin and etoposide.8 Our case was given chemotherapy after surgical resection. No therapeutic guidelines exist. If metastases are present, survival is unlikely despite therapy.

References

  1. Kliem V, Bugge M, Leimenstoll K, Maschek H. Pulmonary blastoma a rare tumour. Clin Investig 1992; 70 : 927-31.
  2. Muller-Hermelink HK, Kaiserling E. Pulmonary adenocarcinoma of fetal type : alternating differentiation argues in favour of a common endodermal stem cell. Virchows Arch A Pathol Anat Histopathol 1986; 409 : 195-210.
  3. Hage E. Electron microscopic identification of endocrine cells in the bronchial epithelium of human foetuses. Acta Pathol Microbiol Scand [A] 1972; 80 : 143-4.
  4. Inoue H, Kasai K, Shinada J, Yoshimura H, Kameya T. Pulmonary blastoma: comparison between its epithelial components and fetal bronchial epithelium. Acta Pathol Jpn 1992; 42 : 884-92.
  5. Berho M, Moran CA, Suster S. Malignant mixed epithelial/mesenchymal neoplasms of the lung. Semin Diagn Pathol 1995; 12 : 123-39.
  6. Koss MN, Hochholzer L, O’Leary T. Pulmonary blastomas. Cancer 1991; 67 : 2368-81.
  7. Barson AJ, Jones AW, Lodge KV. Pulmonary blastoma. J Clin Pathol 1968; 21 : 480-85.
  8. Cutler CS, Michel RP, Yassa M, Langleben A. Pulmonary blastoma : a case report of a patient with a 7-year remission and review of chemotherapy experience in the world literature. Cancer 1998; 82 : 462-67. 

SEIZURES IN CHILDREN

‘Buccal midazolam is more effective than rectal diazepam for treatment of children with seizures in a hospital emergency department’

Intravenous access is not always available for emergency drug treatment for children with acute seizures. The traditional alternative is rectal diazepam. John McIntyre and colleagues compared this drug with buccal midazolam in a randomised controlled trial in four UK hospitals. In 219 cases, buccal midazolam was more effective than rectal diazepam, and the rate of respiratory depression did not differ. The researchers conclude that buccal midazolam is not only a more effective option, but also may have important clinical advantages and be more acceptable to patients. In a Comment, Max Wiznitzer suggests that emergency room treatment need not wait for intravenous access, and that buccal midazolam could be the preferred treatment outside the hospital.

BMJ, 2005; 182, 205.

GIVE ANTIBIOTICS EVEN IF URINE DIPSTICK IS NEGATIVE

Women with symptoms of uncomplicated urinary tract infection but with a urine dipstick test negative for nitrites and leucocytes may still benefit from antibiotic treatment. In a prospective, double blind, randomised placebo controlled trial including 59 women, Richards and colleagues found that 300 mg of trimethoprime daily for three day reduces the duration of dysuria and constitutional symptoms (feverishness, shivers) when compared with placebo. The number needed to treat was four. The authors say their results support the practice of empirical antibiotic use guided by symptoms.

BMJ, 2005; 331 : 143.

*Dean, Professor of Surgery, Head of the department and Unit head; **Lecturer; ***Asso. Prof.; ****Resident, Department of Surgery, Grant Medical College and Sir J.J.Group of Hospitals, Mumbai-400008.