Pulmonary blastema of childhood (Pleuropulmonary blastema)

Clinical features

  • Rare, aggressive malignant tumour
  • Children under 6 years of age
  • Family history of similar-appearing intrathoracic tumours, or malformations in 30% of the cases (e.g. cystic nephroma, lung cysts)
  • Clinical presentation-respiratory distress
  • X-ray- cystic or solid/cystic mass in the lung, pleura or mediastinum
  • Association to cystic nephroma of the kidney

 

Fig 95 - Pulmonary Blastoma of Childhood - Smear from a transthoracic guided fine needle aspiration composed of a big three-dimensional cellular group of blastematous cells (Giemsa)
Fig 96 - Pulmonary Blastoma of Childhood - Smear from a transthoracic guided fine needle aspiration. Neoplastic cells are round, blastematous with scant cytoplasm and High nuclear/cytoplasmic ratio (Giemsa)

 

  • Blastematous cells
    • Single or cohesive aggregates
    • Small round blue cells
    • Small elliptical nuclei
    • Fine chromatin
    • Inconspicuous nucleoli 
    • Scant cytoplasm
  • Myxoid mesenchymatous stroma
    • Uncommitted
    • Differentiation: rhabdomyosarcomatous, chondrosarcomatous
    • Pleomorphic multinucleated cells have been reported
  • Necrosis
  • Mitosis
  • Hyaline globules (PAS positive, diastase resistant)

 

Immunocytochemistry

  • Cytokeratin: negative
  • CD99: Negative

 

Genetic Studies

  • Trisomy 8

 

Differential Diagnosis

  • Cystic adenomatoid malformation/ other benign lung cystic conditions
    • Absence of blastema
  • PNET
    • Most common in older children
    • Rosettes
    • Absence of mesenchymal differentiation
    • CD99: Positive (membranous pattern)
    • t(11;22)(q24;q12) – (90% of the cases)
  • Metastatic neuroblastoma
    • Background of eosinophilic (HE) fibrillary material
    • Neuroblasts in varying degrees of maturation
    • Rare situation
  • Lymphoblastic lymphoma
    • Lymphoglandular bodies
    • Nuclei with irregular membrane, fine powdery chromatin and inconspicuous nucleoli
  • Rhabdomyosarcoma
    • When this is the only component present, differential diagnosis is impossible
  • Metastatic mesenchymal chondrosarcoma
    • It may be indistinguishable
  • Desmoplastic small cell tumour
    • Coexpression of desmin(dot), cytokeratin (dot), Vimentin and NSE
    • EMA : Positive

 

Main points

  • Unknown histogenesis-probably derived from primitive mesenchymal cells in the lung or pleura
  • Survival at 5 years- 45%
  • Frequent pleural involvement at presentation
  • Type I-better prognosis than type II or III
  • Progression from type I to type II or III is described
X