Contemporary Pathological Classification of Primary Lung Tumors: Integration of Morphology, Immunohistochemistry, and...

This review summarizes the current World Health Organization (WHO) classification of lung tumors, emphasizing key morphological, immunohistochemical, and molecular features relevant to diagnosis and management. REVIEW: Primary pulmonary tumors comprise a heterogeneous spectrum of neoplasms with distinct morphological, immunophenotypic, molecular, and clinical characteristics. The current WHO classification integrates traditional histopathological assessment with immunohistochemical and molecular findings, reflecting advances in our understanding of tumor biology and the growing importance of precision medicine. This review summarizes the major categories of primary pulmonary tumors, including adenocarcinoma, squamous cell carcinoma, adenosquamous carcinoma, large cell carcinoma, sarcomatoid carcinomas, neuroendocrine neoplasms, salivary gland-type tumors, and mesenchymal tumors specific to the lung, as well as selected rare pulmonary neoplasms. Particular attention is given to the defining morphological characteristics and diagnostic criteria of individual tumor entities, relevant immunohistochemical profiles, and recurrent molecular alterations with diagnostic, prognostic, and therapeutic implications. The challenges of diagnosing pulmonary tumors in small biopsies and cytological specimens are also addressed, with an emphasis on the judicious use of immunohistochemistry and preservation of tissues for molecular testing. CONCLUSION: Accurate classification of primary pulmonary tumors requires the integration of morphological, immunohistochemical, and molecular findings within the framework of the current WHO Classification of Thoracic Tumors. Recognition of the characteristic morphological and immunophenotypic features, together with appropriate molecular characterization, is essential for precise diagnosis and optimal patient management. Continued advances in molecular pathology are expected to further refine pulmonary tumor classification and contribute to increasingly personalized therapeutic strategies.