Primitive neuroectodermal tumor of lungs in adults: a rare series of three cases treated with upfront chemo-radiation.

Primitive neuroectodermal tumors (PNETs) are highly malignant small round blue cell tumors of neuroectodermal origin belonging to either central nervous system, autonomic nervous system or peripheral Askin's or Ewing's group of neoplasms. The latter generally arise in soft tissues of trunk or axial skeleton in children and early adolescents. However in adults this entity is very uncommon. Of all peripheral entities, primary PNET of lungs without chest wall or pleural involvement in adults are extremely rare and have been scarcely reported in world literature as single case reports. We hereby report a series of three interesting cases of adult PNET of lung diagnosed and treated in our institute. The chief presenting complaints of these patients were of chest pain, cough and dyspnea. The cases were diagnosed on the basis of imaging and biopsy which confirmed these lesions to be of PNET histology, confirmed by immunopositivity for neuron specific enolase (NSE), synaptophysin, chromogranin, CD 99 and vimentin on immunohistochemistry (IHC). All three were deemed unresectable in view of infiltration of nearby vital organs and high chances of morbidity. They were treated with upfront chemotherapy followed by conformal radiotherapy (RT) to the residual disease to which they showed significant response both clinically and radiologically. Presently these patients are on regular follow-up for over 6 months without any evidence of progression of disease or distant metastasis.