What is torsion of a testicular appendage, and what are its US imaging features?
Torsion of a testicular appendage is the leading cause of an acute scrotum in children. The appendix testis (a remnant of the müllerian or paramesonephric duct) and the appendix epididymis (a remnant of the wolffian or mesonephric duct) are testicular appendages that may undergo twisting, leading to ischemia, infarction, and surrounding inflammatory change. Patients with torsion of a testicular appendage are generally treated conservatively.
On US, imaging findings may include: a ≥5-mm spherical paratesticular nodule along the superior aspect of the testicle or epididymal head; normal testicular blood flow and increased periappendiceal blood flow on Doppler US; scrotal wall thickening; and reactive hydrocele.