Müllerian duct cyst as a cause of acute infantile-onset epididymitis.

Müllerian duct cyst is a congenital anomaly that originates from remnants of the müllerian duct that usually regresses in utero. It is most commonly detected in adult males during the third and fourth decades of life. Müllerian duct cyst is rarely reported in infants less than 1 year of age, in whom diagnosis is difficult because of immaturity of the genital tract. In this case report, we describe the sonographic and CT appearance of a large intrapelvic müllerian duct cyst presenting with acute epididymitis in a 9-month-old infant. The embryological basis, imaging findings and relation to epididymitis are discussed.