A 49 y.o. woman presents with diarrhea and abdominal pain.

what do you see on her CT?


Our patient had a mature teratoma with a malignant transformation.  She had had a previous US in 2017 which showed a bicornuate uterus and a mature teratoma with a second cystic mass near the L ovary.  Mature cystic teratoma is the most common benign ovarian tumor. Rarely, they undergo malignant transformation. The term teratoma comes from the

Greek words for “monster” and “tumor”.


Teratomas are germ cell tumors which contain fat, hair , teeth and cartilage. As a result when they become malignant they are often squamous cell tumors but can be adenocarcinomas or melanomas. A teratoma can be non-malignant and yet highly aggressive, growing rapidly.  This happens in the “growing teratoma syndrome” where  chemotherapy eliminates the malignant elements of a mixed tumor and the pure teratoma which is left grows very rapidly.

A nine y.o. with headache has a teratoma with teeth in the brain

A nine y.o. with headache has a teratoma with teeth in the brain

Teratomas are thought to originate in utero but many are not diagnosed until adulthood. They can be diagnosed in utero on US and if they are large can steal the blood from the fetus  causing heart failure.  Later in life, ovarian teratomas can be responsible for anti-NMDA receptor encephalitis.(N-methyl-D-aspartate receptor  antibody encephalitis) They can also secrete thyroid hormone or alpha feto protein.  While they most often occur in the ovaries, testes and sacrum they can occur in the spinal cord and brain.

Scavuzzo A, Rios S, Arturo X, et al. Growing teratoma syndrome. 2014 Case Reports in Urology. 139425. Doi:10/1155/2014/139425. PMID 25197607.

Chang A, Ganz P, Hayes D, Kinsella T, et al.  Oncology: An Evidence-Based Approach. 2007. Springer Science & Business Media  p. 848.

Gonzalez-Crussi F. Extragonadal teratomas. Atlas of Tumor Pathology. Second series. Fascicle 18;Armed Forces Institute of Pathology, Washington D. D.

Jitsumori M, Munakata S, Yamamoto T. Malignant transformation of mature cystic teratoma after a 10-year interval. 2017. Case Resports in Obstetrics and Gynecology.  Article ID 2947927.