Surgical Resection for a Second Primary Lung Cancer Originating Close to the Initial Surgical Margin for Lung Squamous Cell Carcinoma

Figure 3

Histopathological examination shows that the tumor comprises a main small cell carcinoma component (a) and a smaller squamous cell carcinoma component (b). Immunohistochemically, tumor cells of the small cell carcinoma component show positive staining for CD56 (c) but negative staining for CK5/6 (d). By contrast, cells of squamous cell carcinoma component were positive for CK5/6 (d) but negative for CD56 (c).

(a)

(b)

(c)

(d)