Lepidic and alveolar subepithelial squamous cell carcinoma: expansion of the concept of peripheral squamous cell carcinoma with proposal for revised terminology based on morphologic, immunophenotypic, and clinical analysis of 22 cases

In recent years, peripheral type SCC with alveolar filling growth pattern was described with an increasing prevalence in up to 55% of patients. We describe a series of rare growth pattern of SCC with subtotal or partial growth of tumor cells under reactive type II pneumocytes, termed subepithelial growth. Retrospective case series of 19 resections specimens and 3 biopsies with subepithelial growth of SCC and clinical and radiological correlation is described. All 19 resected SCC showed in histol