Ovarian Cystic TeratomaDetermined Phenotypic Response ofKeratocytes and Uncommon IntracysticFloating Balls Appearance on Sonographyand Computed Tomography

Jhanavi R. Rao, MBBS, Zarine Shah, MBBS, Vasudha Patwardhan, DMRD, Vijay Hanchate, MD,Hemangini Thakkar, MD, Ashwin Garg, DMRD

varian cystic tumors (dermoid cysts), derived from totipotent cells, are com-posed mainly of a cyst lined entirely or partly by epithelium resembling kera-tinized epidermis with sebaceous and sweat glands. The term dermoidemphasizes the preponderance of ectodermal tissue, with the elements

derived from other germ layers being inevitably present.1,2 Sonography3,4 and com-puted tomography (CT)5,6 can easily facilitate diagnosis of these benign cystic fattytumors. Generally, cystic teratomas are classified into 1 of 3 categories on the basis oftheir configuration and components. The first type shows layering of floating debriswithin a tumor6,7; the second type has nodular or palm tree–like mural protrusions3,7;and the third type shows a fat-fluid level.3 We report a case of a dermoid cyst that hadnone of the classic sonographic features. Instead, multiple mobile fat balls were seenwithin the cyst, and no features of calcification, tooth, or bone were shown on sonog-raphy and CT. Also, the golden brown color of the hair in the dermoid was similar tothat of the patient’s scalp hair. To our knowledge, that feature, showing the determinednature of keratocytes, has not been discussed before in the literature. We presentunusual sonographic and CT features of a cystic ovarian teratoma with intracysticmobile spherical masses. The spherical fat balls, some of which were admixed withhair, caused the striking feature of multiple floating masses in the cyst.

Received February 4, 2002, from the Departmentof Radiology, King Edward VII Memorial Hospital,Mumbai, India. Revision requested February 21,2002. Revised manuscript accepted for publicationFebruary 28, 2002.

We thank Vinita Salvi, MD, and residents of theDepartment of Gynecology and Obstetrics for pro-viding the surgical findings.

Address correspondence and reprint requests toAshwin Garg, DMRD, Department of Radiology,King Edward VII Memorial Hospital, Parel, Mumbai400012, India.

AbbreviationsCT, computed tomography

Case Report

A 60-year-old postmenopausal woman, gravida 2, para2, living 2, was evaluated for heaviness and pain in theright iliac fossa of 6 months’ duration. She had mildfever with chills and burning micturition. There wasno notable medical or surgical history. A radiograph ofthe abdomen was unremarkable. Sonography showedthe presence of a large cystic mass in the right adnexacontaining within it numerous floating, highly echo-genic round masses (Fig. 1). The echogenicity of thesemasses characteristically corresponded to that of fat.Multiple linear hyperechoic structures (Fig. 2) wereseen radiating from these masses, which correspond-

© 2002 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 21:687–691, 2002 • 0278-4297/02/$3.50

O

Case Report

ed to hair. Thus a mature cystic teratoma arisingfrom the right ovary was considered as a preopera-tive diagnosis.

Computed tomography, performed to determinethe nature of the lesions and to evaluate the effectsof this mass on adjacent structures, confirmed thesonographic findings. It showed an encapsulated,nonenhancing mass with homogenous low-attenuation internal architecture that measured–30 Hounsfield units. Multiple floating hyperdensefatty masses were seen within (Fig. 3). Serologictesting was done to rule out Echinococcus granulo-sis (considered unlikely); the results were negative.

At laparotomy a large mass of 18 × 25 cm wasseen. It was mildly congested and had twistedaround its pedicle. The mass was easily dissect-ed and removed along with the right ovary. In acut section, the cystic mass was full of viscous,fatty fluid (Fig. 4). There were multiple yellow-white, pultaceous, ball-like masses floating inthe fluid, many of them containing goldenbrown hair (Fig. 5). No calcification or tooth ele-ment was found on gross examination. On retro-spection, we found that the patient also had thesame color hair on her head. Histologic exami-nation showed that the cyst was lined by epithe-lium resembling keratinized epidermis withsebaceous and sweat glands. The histopatholog-ic diagnosis was a benign cystic teratoma. Thepatient’s postoperative course was uneventful.

Discussion

Benign cystic teratomas, among the most com-mon ovarian neoplasms (≈15%–25%), arederived from the primitive germ cells of theembryonic gonad. They occur most often dur-ing active reproductive years, are rare beforepuberty, and are not infrequently seen in post-menopausal women. Although they containwell-differentiated derivatives of the 3 germlayers,1,2 ectoderm, mesoderm, and endoderm,ectodermal elements generally predominate;therefore they are also called dermoid cysts.The melanocytes, ectodermal derivatives, aredistributed in the hair matrix and synthesizemelanin, which is responsible for the color ofhair. There are 2 types of cells: competent anddetermined. Cells that do not alter their pheno-type in response to environmental influencesare known as determined or committed cells,whereas other cells, which are environmentallyresponsive, are described as competent. In ourpatient, the golden brown hair in the dermoidcyst was similar to the hair on her scalp. Thisshows the determined feature of the melano-cytes found in the dermoid cyst.

Dermoid cysts tend to remain concealedunless they assume such a size as to produce apalpable abdominal mass or to cause pain as aresult of torsion, the most common complica-tion caused by the long pedicle they have.Some asymptomatic dermoids are detectedincidentally on abdominal radiography, show-ing calcification or “tooth.” Other less commoncomplications are rupture (1%) and malignant

688 J Ultrasound Med 21:687–691, 2002

Ovarian Cystic Teratoma

Figure 1. Transverse sonogram showing multiple mobile, spherical, echogenicstructures floating in a cystic mass.

Figure 2. Cystic mass with highly echogenic round structures and posterior shad-owing. Multiple linear hyperechoic structures corresponding to hair are shownradiating from the spherical mass into surrounding fatty fluid.

transformation (2%).8 In our case, the post-menopausal woman had pain secondary to tor-sion of the dermoid cyst.

The radiologic diagnosis of cystic teratoma canbe made readily on the basis of sonography, CT,or magnetic resonance imaging. Because anovarian tumor may contain a large number ofrecognizable tissues, including matted hair,well-formed teeth, and semisolid sebaceousmaterial, the variety and preponderance ofinternal contents presumably account for thespectrum of sonographic appearances. Onsonography, a teratoma may appear as a pre-dominantly cystic, solid, or complex mass.3,9

However, certain features are considered specif-ic. These include an axial location, cephalad tothe urinary bladder,10 an echogenic mural nod-ule (the “dermoid plug” or “dermoid nipple”),3 afat-fluid or hair-fluid level,11 and distal acousticshadowing produced by a highly echogenic mix-ture of matted hair and sebum, termed the “tipof the iceberg” sign.12 Another specific sign is“dermoid mesh,” i.e., multiple linear hyper-echoic interfaces produced by the floating hairfibers within the cyst.13

However, our case did not have any of theseclassic features; instead, there were multipleround, floating, echogenic fat balls seen withinthe large anechoic cyst. Also, there was no calci-fication or toothlike structure shown on sonog-raphy and CT. On review of literature, we foundonly a small number of cases of cystic teratomaswith multiple mobile spherical masses. Thesehave been found in the ovary,14,15 retroperi-toneum,16 and mediastinum.17 The compositionof these masses was different in different loca-tions: in the case of a cystic teratoma of theovary, the nodules consisted of sebaceous debriswith skin squames and hair15; and in a maturecystic teratoma of the mediastinum, mobileglobules consisted of pastelike material, fat, andhair.17 In a retroperitoneal mature cystic ter-atoma, fat deposition was seen around hair tis-sue16; these spherical structures have beencalled intracystic fat balls.14,16 In our patient,spherical masses consisted of pastelike materialand fat, and some were intermixed with hair.Other than cystic teratoma, intracystic multiplespherules also have been described in an epider-moid cyst in the floor of the mouth.18 Accordingto Kawamoto et al,19 the appearance of multiplespherules floating within a pelvic cystic tumorhas not been found in other tumors; therefore,

this appearance is pathognomonic for a cysticteratoma.

Computed tomography, with its unique abilityto discriminate between tissues of differentattenuations, can display with precision theinternal architecture of the lesion and can showthe presence of even a small amount of fat;therefore, CT is helpful in those instances inwhich plain radiography and sonography arenonspecific. The specific CT characteristics arethose of a predominantly fatty mass with adense dependent element (mixture of fat, hair,

J Ultrasound Med 21:687–691, 2002 689

Rao et al

Figure 3. Contrast-enhanced CT showing multiple round, fat-dense masses float-ing within the cyst.

Figure 4. Cut section of the specimen showing multiple mulberry-shaped, round,solid fatty masses floating in the fluid inside the thinly encapsulated dermoid cyst.

debris, and fluid) and globular foci of calcifica-tion (teeth, abortive tissue, or both) in a solid pro-tuberance. Correlation with sonographic imageshas shown that in many cases, as in our case, theanechoic cystic component is pure sebum(which is liquid at body temperature) rather thanfluid.20 The absence of multiple lesions interfac-ing within the sebum is the likely explanation forits anechoic appearance on sonography.4 On thecontrary, a mixture of matted hair, soft tissue, andfat in the dermoid plug or floating masses ishighly echogenic because of numerous tissueinterfaces.21 Sonography in isolation or in com-bination with radiography has contributedconsiderably to the correct diagnosis; however,an echogenic dermoid may appear similar tobowel gas and may be overlooked. Similarly,echogenic fluid-filled masses may occasionallysimulate solid lesions.

Magnetic resonance imaging, with its bettersoft tissue contrast and multiplanar imaging,has an advantage over sonography and CT. Toavoid radiation hazards, magnetic resonanceimaging has become the procedure of choicefor pelvic imaging.7 The cystic teratoma hasthe notable characteristic of fat (hyperintenseon T1-weighted images) and water (hypo-intense on T1-weighted images and hyper-intense on T2-weighted images). However,calcifications, bone, hair, and fibrous tissue, allfrequently found in teratomas, are of low sig-nal intensity.

In summary, unusual associated findings of amature cystic teratoma may result in occasionaldiagnostic difficulty. Only a small number ofcases of cystic teratomas with multiple mobilespherules or globules have been reported. Thiscase further substantiates the idea that the sono-graphic and CT appearance of multiple floatingmasses in a cystic mass in the pelvis is pathog-nomonic for a cystic teratoma of the ovary.

References

1. Novak ER, Woodruff JD. Novak’s Gynecologic andObstetric Pathology With Clinical and EndocrineRelations. 8th ed. Philadelphia, PA: WB Saunders Co;1979:476–503.

2. Scully RE. Germ cell tumors. In: Tumors of the Ovaryand Maldeveloped Gonads. Washington, DC:Armed Forces Institute of Pathology; 1979:226–286. Hartmass WH (ed). Atlas of Tumor Pathology;Series 2, Fascicle 16.

3. Quinn SF, Erickson SE, Black WC. Cystic ovarian teratomas: the sonographic appearance of the der-moid plug. Radiology 1985; 155:477–478.

4. Laing FC, Van Dalsem VF, Marks WM, Barton JL,Martinez DA. Dermoid cysts of the ovary: their ultra-sound appearances. Obstet Gynecol 1981; 57:99–104.

5. Freidman AC, Pyatt RS, Hartman DS, Downey EF Jr,Olson WB. CT of benign cystic teratomas. AJR Am JRoentgenol 1982; 138:659–665.

6. Skanne P, Heuber KH. Computed tomography ofcystic ovarian teratomas with gravity-dependent lay-ering. J Comput Assist Tomogr 1983; 7:837– 841.

7. Togashi K, Nishimura K, Itoh K, et al. Ovarian cysticteratoma: MR imaging. Radiology 1987; 162:669–673.

8. Kurman RJ. Blaustein’s Pathology of the FemaleGenital Tract. 4th ed. New York, NY: Springer-Verlag;1994.

9. Sandler MA, Silver TM, Karo JJ. Gray scale ultrasonicfeature of ovarian teratomas. Radiology 1979;131:705–709.

10. Morley P, Barnett E. The use of ultrasound in thediagnosis of pelvic masses. Br J Radiol 1970; 43:602–616.

11. Gottesfeld KR. The use of ultrasound in gynecologi-cal diagnosis. Appl Radiol 1978; 7:132–140.

690 J Ultrasound Med 21:687–691, 2002

Ovarian Cystic Teratoma

Figure 5. Specimen showing golden brown hair admixed with fatty masses.

12. Guttman PH Jr. In search of the elusive benign cys-tic ovarian teratoma: application of the ultrasound“tip of the iceberg” sign. J Clin Ultrasound 1977;5:403– 406.

13. Malde HM, Kedar RP, Chadha D, Nayak S. Dermoidmesh: a sonographic sign of ovarian teratoma [let-ter]. AJR Am J Roentgenol 1992; 159:1349–1350.

14. Muramatsu Y, Moriyama N, Takayasu K, Nawano S,Yamada T. CT and MR imaging of cystic ovarian ter-atoma with intracystic fat balls. J Comput AssistTomogr 1991; 15:528–529.

15. Otigbah C, Thompson MO, Lowe DG, Setchell M.Mobile globules in benign cystic teratoma of theovary. BJOG 2000; 107:135–138.

16. Fujitoh H, Akiyosi S, Takoda S, Katsuki K, Okuda K.Hepatobiliary and pancreatic imaging: retroperi-toneal mature cystic teratoma with a fat ball. J Gastroenterol Hepatol 1998; 13:540–549.

17. Hession PR, Simpson W. Case report: mobile fattyglobules in benign cystic teratoma of the medi-astinum. Br J Radiol 1996; 69:186–188.

18. Lohaus M, Hansmann J, Witzel A, FlechtenmacherC, Mende U, Reisser C. Ungewoehnlicher sono-graphischer Befund einer Epidermoidzyste. HNO1999; 47:737–740.

19. Kawamoto S, Sato K, Matsumoto H, et al. Multiplemobile spherules in mature cystic teratoma of theovary. AJR Am J Roentgenol 2001; 176:1455–1457.

20. Seth S, Fishman EK, Buck JL, Hamper UM, SandersRC. The variable sonographic appearances of ovari-an teratomas: correlation with CT. AJR Am JRoentgenol 1988; 51:331–334.

21. Fleischer AC, Cullinan JA, Kepple DM, Williams LL.Conventional and color Doppler transvaginalsonography of pelvic masses: a comparison of rela-tive histologic specificities. J Ultrasound Med 1993;12: 705–712.

J Ultrasound Med 21:687–691, 2002 691

Rao et al