Anaplastic Lymphoma Kinase (ALK) protein expression by Immunohistochemistry
A total of 54 cases were evaluated for ALK protein expression after excluding 6 cases for technical reasons. ALK expression was mainly cytoplasmic and granular in nature (Fig.1), nuclear positivity was not seen. Some cases also showed intense membranous positivity and strong positivity in the neuropil. ALK expression was heterogeneous in 17 out of 54 (32%) cases. H-scoring was performed as described in the methods and overall, 35 cases (65%) with an H-score of ≥100 showed moderate to strong ALK positivity, whereas 19 cases (35%) with <100 H-score were negative (Fig.1).