Certified Tumor Registrar (CTR) Practice Exam

For a tumor histology of rhabdomyosarcoma, what is the most likely primary site?

1. Blood vessel

2. Bone

3. Skeletal muscle

4. Uterus

The correct answer is: Skeletal muscle

Rhabdomyosarcoma is a type of malignant tumor that arises from mesenchymal tissue, particularly from skeletal muscle. This cancer is most commonly found in children and is characterized by its origin in the embryonic cells that develop into skeletal muscle tissue. When considering the potential primary sites for rhabdomyosarcoma, skeletal muscle stands out as the most likely location because the tumor is derived from the same type of tissue. Unlike other options such as blood vessels, bone, or uterus, which do not have a direct histological relationship with the underlying skeletal muscle tissue, skeletal muscle serves as the inherent source of rhabdomyosarcoma's development. In clinical practice, understanding the primary site of tumor origin is crucial for diagnosis, treatment planning, and prognostication. Rhabdomyosarcoma can present in various anatomical locations, but skeletal muscle remains the primary site due to its histological characteristics and the nature of the tumor itself. This distinction helps healthcare professionals identify and categorize the tumor accurately, leading to appropriate management strategies.