FOLR1 and ovarian carcinoma: Using a cohort of 37 ovarian cancer cases with accompanying internal control tissue, selected from institutional archives based on histological diagnosis, adequate tumor representation, and technically acceptable FRα immunostaining, we focus on three key parameters: (1) adequacy of internal control tissue, (2) FRα positivity versus negativity, and (3) estimation of the percentage of tumor cells exhibiting FRα staining.