EUS is valuable for assessing SETs but has a lower diagnostic accuracy for lesions <30 mm. EUS-FNAB is the most commonly used tissue sampling method, with an 80% diagnostic yield (20/25 cases), though some samples remain non-diagnostic. Immunohistochemistry staining for leiomyomas showed positivity for smooth muscle actin (SMA) and desmin, while GISTs were CD34 and KIT (c-KIT) positive, aiding in differentiation. Pathological confirmation is often necessary for a definitive diagnosis. The gene discussed is SMN1; the disease is leiomyoma.