Ovarian collision tumor

Case contributed by Ammar Haouimi


Pelvic pain with a palpable mass. Complex pelvic mass on ultrasound.

Patient Data

Age: 25 years
Gender: Female

The MRI sequences demonstrate two contiguous masses arising from the left ovary:

  • the superior mass appears well-circumscribed multiloculated measuring 14 x 12 x 7.5 cm, composed of multiple loculi of various sizes. up to 8 cm. It displays a low signal on T1 with some loculi of high signal, high signal T2 with enhanced septa. No restricted diffusion on DWI/ADC. No soft tissue component is noted. Minimal peritoneal effusion. No pelvic lymphadenopathy
  • the posteroinferior mass appears well-defined measuring 9.5 x 7.5 x 7 cm of complex signal intensity. The main component is of fatty signal attenuated on fat sat sequences

Normal appearance of the uterus and right ovary.

Case Discussion

MRI features of two distinct tumors in the same ovary (mucinous cystadenoma and mature teratoma) most consistent with an ovarian collision tumor (pathologically proven).

Ovarian collision tumors are considered as an uncommon ovarian neoplasm where there is co-existence of two adjacent but histologically distinct tumors in an ovary with no histologic admixture at the interface.

They are most commonly composed of ovarian teratoma (typically mature cystic teratoma of the ovary) and an ovarian cystadenoma or ovarian cystadenocarcinoma (typically mucinous).


Additional contributor: ZE. Boudiaf, MD, CHU, Constantine, Algeria

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