Fig. 2

Autopsy and pathologic findings of the acantholytic squamous cell carcinoma of the lung. a An axially cut section of left lung shows the upper lobe tumor (an arrow) and hemorrhagic lower lobe. b Axially cut sections (numbers 1–8) of the mediastinum demonstrate metastatic lymph nodes (arrows) in the ipsilateral and contralateral sides. Stars indicate airway of the trachea and its bifurcation. The numbered, dotted lines correspond to the numbers of the cut sections. c–d The left upper lobe tumor includes pseudoacinar nests containing discohesive atypical cells. Individual atypical tumor cells are also seen in the stroma (d). e–i The monomorphic and discohesive tumor cells that are associated with squamoid cells or nests (e) show filling in some alveolar spaces (f), pulmonary lymphangitis carcinomatosis (g), left, low magnification; right, D2–40 immunostained section), and lymph node metastasis (h) and its inset, high magnification of (h). The papanicolaou-stained smears (I) prepared from bilateral pulmonary effusion confirm acantholytic tumor cells including signet-ring cells (arrow) that are also seen in (f) (arrow). Images of (c–h) are taken from sections stained with hematoxylin and eosin. Bars indicate 3 cm in (a–b), 100 μm in (c–f), and (i), and 1 mm in (g) and (h)