adenocarcinoma in situ


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  • Clinical

    • location: peripheral, close to pleura

  • Criteria

    • size < 3 cm
    • solitary
    • pure lepidic growth (outlines alveoli)
    • lacks invasion (stromal, vascular, pleural)
    • lacks invasive patterns (acinar, papillary, solid, micropapillary)
    • lacks spread through airspace: no intraalveolar cells
    • mostly nonmucinous (type II pneumocytes or clara cells), rarely mucinous
    • minimal atypia
    • septal widening with sclerosis/elastosis is common
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