Successful immunotherapy with ipilimumab and nivolumab in a patient with pulmonary sclerosing pneumocytoma.

Pulmonary sclerosing pneumocytoma (PSP) is a rare form of lung cancer that occasionally presents with lymph node and extrapulmonary metastases, and multiple lesions. The treatment of metastatic PSP remains undefined. This study reports the case of a 48-year-old female patient diagnosed with PSP following surgical intervention for a solitary nodule in the left lower lobe. Four years later, recurrence occurred in the left hilar and mediastinal lymph nodes, necessitating an additional resection. Concurrently, sacral metastases developed and required palliative radiotherapy. Genetic analysis identified an AKT1 E17K mutation, characteristic of PSP, and absence of programmed cell death ligand 1 (PD-L1) expression in the tumor. Two years post-recurrence, the tumor recurred in the left mammary gland and mediastinal lymph nodes. Combination immunotherapy with ipilimumab and nivolumab yielded a significantly positive response in this metastatic PSP case. This is the first reported case of successful treatment of multiple distant metastatic PSP with ipilimumab and nivolumab, following the failure of various local treatments. Further case series are warranted to validate the efficacy of immunotherapy in metastatic PSP.