Fig. 3.

On low power magnification (X4 objective) the core biopsy shows representative areas of the targeted lung mass. The tumor is hypercellular and not forming epithelial acini or cohesive sheets.

Fig. 3b: On high power magnification (X20 objective) there are spindle cells arrayed in fascicles, mixed with inflammatory cells including numerous plasma cells. These spindle cells show myofibroblastic differentiation by immunohistochemistry.

Fig. 3c: Smooth muscle actin is positive in the cytoplasm of the spindle cells supporting the myofibroblastic differentiation.

Fig. 3d: Pancytokeratin immunohistochemistry stain is negative in the spindle cells. The cytokeratin highlighted the epithelial cells in the entrapped airways.

Fig. 3e: Kappa (right side) and lambda (left side) immunohistochemistry stains show polyclonal population of plasma cells.

Fig. 3f: Wedge lung resection from the left upper lobe measuring 9.8-/4.9/3.2 cm, multiple stapled margin present. Well defined subpleural mass solid, 4/2.5/3.2 cm with cystic area 1.5/1.2/1.3 cm with free safety margin.