α-Smooth Muscle Actin Expression in Relation to Invasive Histopathological Features of Papillary Thyroid Carcinoma Lathifah Nurul Fajri1,2, Nila Kurniasari1,2*, Heriyawati1,2 Abstract Papillary thyroid carcinoma (PTC) generally has a favourable prognosis, but some tumours show invasive histopathological features associated with more aggressive behaviour. Alpha-smooth muscle actin (α-SMA), a marker of activated