The Extent of Expression of Thyroid Transcription Factor 1, Cytokeratin 7, and Anaplastic Lymphoma Kinase in Lung Adenocarcinoma

BACKGROUND: New forms of genetic alteration were developed giving a new era of lung adenocarcinoma (AdC) with diverse clinical and pathological features. AIM AND OBJECTIVES: The aim is to investigate the ALK-rearranged gene as one of these genetic alterations in AdC. The role of TTF-1 and CK7 is to exclude the metastases. MATERIAL AND METHODS: Paraffin-embedded 50 AdC specimens were cut into 4-mm thick sections and stained with the primary antibody, using an anti-TTF-1 antibody, (all at a 1:200 dilution, mouse monoclonal antibody; Dako, Denmark), anti-CK 7 antibody (DAKO, Carpentaria, CA), and the rabbit monoclonal anti- ALK antibody (D5F3) (Ventana, USA). Positive reactivity was considered as brown nuclear immunostaining for TTF-1 and cytoplasmic for CK 7and both cytoplasmic and nuclear for ALK. RESULTS: The median age was 56±2, with male to female ratio 7:3. Forty-four cases revealed a mixed pattern (88%), with focal intraluminal mucin. Forty-one cases (82%) were positive for TTF-1, of these; weak (13; %), moderate (16; %) and strong (12; %). Regarding CK7; 48 cases (96%) were positive; weak (7 cases; 14.5; %), moderate (18 cases; 37.5%) and strong (23 case; 47.9 %) of the positive cases. Regarding D5F3; five cases (10%) were positive; weak (1 case; 20 %), moderate (2 cases; 40 %) and strong (2 cases; 40%) out of the positive cases. Four ALK-positive cases were male and ALK-positive patients ranged from 42-55 years with median 48. CONCLUSION: Despite the incidence of ALk-AdC is uncommon, it might be suspected in lesions of lower age group especially with mucinous foci.