[Rare subtypes of lung cancer]

In Europe, a rare cancer is defined as having an incidence rate of less than 6/100,000. Rare lung cancers encompass many entities defined by the 2021 WHO classification of thoracic tumors, and represent around 10% of all lung cancers. Rare lung cancers involve several histological types (carcinoma, sarcoma and lymphoma), each of which comprises several entities. The management of these patients with rare cancers requires specific medical expertise at every level (diagnosis, treatment and follow-up). These patients should therefore be referred to expert centers affiliated with national networks, giving them appropriate care and better access to innovative treatments. The deployment of systematic molecular characterization of these tumors has allowed for the identification and better characterization of specific entities. Some entities are specific to the lung, while others are more commonly found in other organs. In this review, we will only consider malignant lung tumors with an incidence of less than 1%.