Purpose or Case Report: A 3-year-old male presented to the emergency department with a 3-day history of wheezing, dyspnea, and mild hypoxia. Patient was afebrile with diminished left-sided breath sounds. Chest radiograph demonstrated expansile opacification of left upper lung, raising concern for pneumonia and prompting ceftriaxone administration. Patient did not improve on antibiotics, and laboratory findings remained inconclusive for infection. A contrast-enhanced chest CT revealed a large left upper lung mass with associated airway compression and atelectasis. Subsequent biopsy and histology initially proposed unspecified sarcoma and malignant spindle cell neoplasm; later refined to pleuropulmonary blastoma (PPB) type III. Fluorodeoxyglucose (FDG) PET-MRI and bone marrow biopsy confirmed localized disease. Molecular genetic testing revealed DICER1 mutation. Patient completed 12 cycles of IVADo (ifosamide, vincristine, actinomycin-D, and doxorubicin) chemotherapy and underwent left lung pneumonectomy, now 2 years in remission.

PPB is a rare embryonal lung neoplasm in children (ages 0-6) classified into cystic (type I/Ir), mixed cystic and solid (type II), and purely solid (type III). Pathogenic germline DICER1 variations have been seen in PPB, as well as cystic nephroma, botryoid-type embryonal rhabdomyosarcoma, and ovarian sex cord-stromal tumors. Diagnosis of PPB can be initially challenging as they may present as pneumonia with nonspecific respiratory symptoms including dyspnea, chest pain, cough, and fever. Pathologic subtype is the only independent prognostic factor (with types II and III having worse outcomes). Treatment varies depending on the type and location of PPB. Given this tumor’s aggressive nature, accurate diagnosis and early treatment with surgical resection and/or concurrent chemotherapy is critical.
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