Figure 2

Histological and FISH analysis. Microscopic and immunohistochemical examination of the right lung cancer reveals a mucinous cribriform pattern (a) (HE stain, ×200), which is positive for ALK (b) (immunohistochemical staining, ×200). The right lung cancer also contains a bronchioloalveolar pattern (c) (HE stain, ×200), which is again positive for ALK (d) (immunohistochemical staining, ×200). On the other hand, the left lung cancer is composed singly of a bronchioloalveolar pattern (e) (HE stain, ×200), which is negative for ALK (f) (immunohistochemical staining, ×200). FISH analyses revealed EML4-ALK fusion gene in the tumor of the right lung (g-j). FISH signals in a single tumor cell are shown. (g)-(i) EML4-ALK fusion FISH. The signals for ALK gene (g) and EML4 gene (h) are indicated by green and red dots, respectively. The signal for EML4-ALK fusion gene is indicated by a white arrow (i). (j) ALK split FISH. The signals for 5′ and 3′ probe for ALK gene are indicated by green and red dots, respectively. Split of the green and the red dots is consistent with the presence of EML4-ALK fusion gene.