Solid (Type 3) pleuropulmonary blastoma

Introduction: Pleuropulmonary blastoma is a rare solid and/or cystic progressive and aggressive malignant intra-thoracic tumor of childhood which belongs to a group of dysontogenetic neoplasms such as Wilms tumor, neuroblastoma and hepatoblastoma. The incidence of pleuropulmonary blastoma ranges between 0.25 and 0.5% of primary lung tumors making this entity a rare primary malignant lung tumor. Case Report: A two-month-old male neonate was referred from a regional hospital with a three-day history of cough, fever and shortness of breath. No previous medical history reported. The patient was delivered at term through a normal vaginal delivery which was uneventful. Birth weight 3 kg, length 48 cm, Apgar score 10/10 and the head circumference was 35 cm. The patient’s retro-viral disease status was negative. On percussion there was dullness and bilateral crepitations. There was bilateral decreased air-entry. No signs of cardiac failure. The rest of the systems were within Luvo Gaxa1, Bafana Hlatshwayo2, Aletta Lefentse Motene3 Affiliations: 1MBChB, MMed (Rad D), Paediatric Radiology fellow, Diagnostic Radiology and Imaging, R, South Africa; 2Dip Rad Diag, MBChB, MMed Rad D, Senior Specialist, Diagnostic Radiology and Imaging, Polokwane-Mankweng Hospital Complex, Polokwane, Limpopo, South Africa; 3MBchB, Fc Paed, Fellow in Paediatric Pulmonology, Senior Specialist, Paediatrics, Polokwane-Mankweng Hospital Complex, Polokwane, Limpopo, South Africa. Corresponding Author: Luvo Gaxa, P. O. Box 11381, Bendor Park, Polokwane, South Africa; E-mail: luvogaxa@yahoo. com Received: 21 April 2016 Accepted: 03 September 2016 Published: 14 January 2017 normal limits. The arterial blood gases showed respiratory acidosis with hypoxia. Chest X-ray showed a white out of the right hemithorax and CT scan of the chest showed a large soft tissue mass in the right hemithorax associated with free fluid in the right hemithorax and the biopsy was performed which confirmed the diagnosis of a pleuropulmonary blastoma. The pleuropulmonary blastoma was a solid type (Type 3). Conclusion: Pleuropulmonary blastoma poses a diagnostic challenge because it does not have specific clinical or radiological features. The late diagnosis and delayed treatment of pleuropulmonary blastoma are associated with a deadly prognosis.


INTRODUCTION
The incidence of pleuropulmonary blastoma ranges between 0.25 and 0.5% of primary lung tumors making this entity a rare primary malignant lung tumor [1]. Pleuropulmonary blastomas have been described from the perinatal period until adulthood and symptoms are generally non-specific and include fever, chest or abdominal pain, dry cough, persistent infection despite medical therapy, shortness of breath and pneumothorax [1].
The differential diagnosis of congenital pulmonary adenomatoid malformation poses a diagnostic challenge and also a definitive diagnosis of pleuropulmonary blastoma cannot be secured only based on clinical and radiological investigations [2].

CASE REPORT
A two-month-old male neonate was referred from a regional hospital with a three-day history of cough, fever and shortness of breath. No previous medical history reported. The patient was delivered at term through a normal vaginal delivery which was uneventful. Birth weight 3 kg, head circumference 35 cm, birth length 48 cm, Apgar score 10/10. The patient's retro-viral disease status was negative.
On examination the neonate has normal growth and development. On admission the body weight was 4.5 kg, head circumference was 38 cm and the length was 57 cm. There were no pallor and no cyanosis. The patient was in severe respiratory distress with use of the accessory muscles (respiratory rate 22 beats/minute). The patient was pyrexial (temperature 38°C).
On percussion there was dullness and bilateral crepitations. There was bilateral decreased air-entry and no signs of cardiac failure. The rest of the examination were within normal limits. Chest X-ray showed a dense opacification of the right hemithorax ( Figure 1).
The computed tomography scan of the chest was performed following the chest X-ray findings for further characterization of the chest X-ray findings. Computed tomography scan of the chest showed a large right hemithorax mass associated with free fluid in the right hemithorax ( Figure 2).
The patient was intubated and then admitted in pediatric intensive care unit. He was ventilated for nine days and later discharged to the pediatric pulmonology ward. Ultrasound guided biopsy was performed when the patient's condition had stabilized.
The biopsy results were as follows: Microscopy: Histological examination showed sheets of oval to spindle shaped cells forming fascicles. The cells lack an epithelial component (Figures 3 and 4).
Immunohistochemistry: In the presence of an adequate control, CD 99 is diffusely positive and stains with moderate intensity. BCL-2 is also diffusely positive and stains with a strong intensity. Both cytokeratin stains, CK5/6 and MNF116 are negative. CD 34 is negative. The above mentioned features are those of a pleuropulmonary blastoma. The pleuropulmonary blastoma was a solid type (Type 3). Following the histopathology findings the patient was then referred to the pediatric surgical department for further management. However; the patient's condition deteriorated and he demised before the pediatric surgical intervention.

DISCUSSION
Pleuropulmonary blastoma is a rare solid and or cystic progressive and aggressive malignant intrathoracic tumor of childhood which such as Wilms tumor, neuroblastoma and hepatoblastoma belongs to a group of dysontogenetic neoplasms [1,2]. Congenital pulmonary adenomatoid malformation is a rare developmental congenital abnormality of the lower respiratory tract whose etiology is unknown [3].
The incidence of pleuropulmonary blastoma ranges between 0.25 and 0.5% of primary lung tumors making this entity a rare primary malignant lung tumor [1].
Barnard was the first person to describe pleuropulmonary blastomas in 1952. He named them embryomas and the tumors were re-defined by Spencer and Mavivel in 1961 and 1988 respectively. Since then only 150 cases have been reported in the English literature until 2010 [1]. Pleuropulmonary blastomas have been described from the perinatal period until adulthood and symptoms are generally non-specific and include fever, chest or abdominal pain, dry cough, persistent infection despite medical therapy, shortness of breath and pneumothorax [1].
The differential diagnosis of congenital pulmonary adenomatoid malformation poses a diagnostic challenge and also a definitive diagnosis of pleuropulmonary blastoma cannot be secured only based on clinical and radiological investigations [2].
Late diagnosis and delayed treatment of pleuropulmonary blastoma are associated with a deadly prognosis [2].
The classification of pleuropulmonary blastoma according to histological features by Priest et al. is as follows [2]: 1. Type 1 (Pure cystic) 2. Type 2 (Cystic and solid) 3. Type 3 (Purely solid) The recurrence rate of type 1 pleuropulmonary blastoma is lower compared to type 2 and type 3 PPB and there is no metastatic focus associated with type 1 [2]. Progression of pleuropulmonary blastoma from type 1 to type 3 is speculated as a natural history of PPB and this tumor can occur in the lungs, pleura, mediastinum and the diaphragm [4,5].
According to Priest et al. a five-year survival rate for type 1 PPB is 83% while for type 2 and type 3 is 42% [4].
Association of a pleuropulmonary blastoma with the familial cancer syndrome raises suspicion that the PPB may have a genetic basis [6].
Type 2 and type 3 PPB metastasize to the brain, liver and the bone in 30% of cases while type 1 PPB rarely metastasizes [7].
The histological characteristics of PPB are that of blastomatous component that is variable associated with sarcomatous areas that have rhabdomyoblastic or chondroblastic differentiation [8].
The ultimate treatment for children with pleuropulmonary blastoma is complete surgical resection with clear margins usually requiring a lobectomy [7,9].

CONCLUSION
The diagnosis of a pleuropulmonary blastoma needs a multidisciplinary approach which involves the pediatricians, radiologists and the histopathologists. The ultimate diagnosis is secured through biopsy and the ultimate treatment is surgical. *********