Clinical History
30-year-old female presented with large abdominal swelling.
Imaging Findings
30-year-old female presented with large painless pelviabdominal mass. US revealed large unilocular cystic mass with multiple echogenic nondependant masses that move freely on changing patient’s
position. One large mass was heterogeneous with mild sound attenuation (arrow in 1a). All masses showed echogenic reflectors representing hair. On CT scan, these masses were hypodense (-18 to -20 HU)
and non enhancing. There was no evidence of fat density within cyst wall or cavity. Small calcific focus was detected in its posterior wall. The cyst was excised. Pathologic study revealed cystic
mass measuring 21x20x9 cm, with smooth gray-white, glistening surface. On bisection, many balls of thick sebaceous material mixed with hair were floating within mucinous fluid. Microscopic
examination revealed; ectodermal element (hair follicles, sebaceous glands), Endodermal element (respiratory epithelium), Mesodermal element (bone) and Glial element.
Discussion
Mature teratoma is the most common benign ovarian tumor in women less than 45 years old. These teratomas are composed of mature tissue from two or more embryonic germ cell layers. Most mature cystic
teratomas are asymptomatic. Abdominal pain or other nonspecific symptoms occur in the minority of patients. Mature cystic teratomas grow slowly at an average rate of 1.8 mm each year. The tumors are
bilateral in about 10% of cases. The gross pathologic appearance of mature cystic teratomas is characteristic. The tumors are unilocular in 88% of cases and are filled with sebaceous material, which
is liquid at body temperature and semisolid at room temperature. There is usually a raised protuberance projecting into the cyst cavity known as the Rokitansky nodule. Most of the hair typically
arises from this protuberance. Bone or teeth when present, tend to be located within this nodule. Squamous epithelium lines the wall of the cyst. Ectodermal tissue (skin derivatives and neural
tissue) is invariably present. Mesodermal tissue (fat, bone, cartilage, muscle) is present in over 90% of cases, and endodermal tissue (eg, gastrointestinal and bronchial epithelium, thyroid tissue)
is seen in the majority of cases. Adipose tissue is present in 67%–75% of cases, and teeth are seen in 31%. US findings in mature cystic teratomas vary from a cystic lesion with a densely
echogenic tubercle (Rokitansky nodule) projecting into the cyst lumen, to a diffusely or partially echogenic mass with the echogenic area usually demonstrating sound attenuation owing to sebaceous
material and hair within the cyst cavity, to multiple thin, echogenic bands caused by hair in the cyst cavity. At CT, fat attenuation within a cyst, with or without calcification in the wall, is
diagnostic for mature cystic teratoma. The most common types of teratoma, mature and immature teratoma, both demonstrate lipid material at CT and MR imaging. This material consists of sebaceous
material within the cyst cavity or adipose tissue within the cyst wall or dermoid plug. A minority of mature cystic teratomas will not demonstrate a sebum-filled cyst cavity. However, these teratomas
usually demonstrate evidence of fat in the wall or in the Rokitansky nodule. Yamashita et al reported detecting such small foci of fat (but no sebaceous material) with opposed-phase imaging in seven
of 78 mature cystic teratomas. No fatty tissue or sebaceous material was identified at MR imaging in five of the 78 lesions. In addition, intracystic nondependent spheres of lipid material can
occasionally be identified in a mature cystic teratoma, producing a striking appearance. Mature cystic teratoma may be complicated by torsion, rupture, or malignant degeneration. Rupture causes
leakage of the liquefied sebaceous contents into the peritoneum and resulting in granulomatous peritonitis. Torsed teratomas are larger than average (mean diameter, 11 cm versus 6 cm); this
enlargement could be the result of the torsion rather than the cause of it. Torsion of a teratoma, even in chronic cases, does not eradicate the fatty elements.
Differential Diagnosis List
Ovarian Mature Cystic Teratoma with floating sebaceous spheres.
Final Diagnosis
Ovarian Mature Cystic Teratoma with floating sebaceous spheres.
