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 neuroectodermal neoplasms affecting bone and soft tissues (1) accounting for 4–17% of all pediatric soft tissue tumors (2) while adult affection are extremely rare and have a very poor prognosis. They are characterized by small round blue cells, thus sharing pathological similarity with other small round cell tumors (1) and exhibiting diverse clinical manifestations. PNETs are highly uncommon comprising 5% of all small round cell tumors (3). Peripheral primitive neuroectodermal tumors (pPNETs) are the rarest class of PNET belonging to the Ewing’s or Askin’s family of tumors. They are highly aggressive and have an average life expectancy of 8 months (4). Thoracic lesions generally arise from intercostal nerves (5) of chest wall or pleura while primary adult intrapulmonary PNETs are exceedingly rare with very few documented cases till date. Multimodality therapeutic approach is generally considered with maximal safe surgical resection followed by adjuvant chemo-radiation (6,7). However, inoperable cases can be managed with chemotherapy followed by radiotherapy (RT) (8) with satisfactory results. We present the second largest case series of PNET lung after Weissferdt and Moran (9) with an idea to highlight their extreme rarity, clinicopathological characteristics, therapeutic challenge, final outcome and subsequent follow-up. To the best of our knowledge, this is the first series till date where all cases have been treated with chemo-radiation with significant response to therapy