Mobile globules in benign cystic teratoma of the ovary

Abstract

A 39 year old nulliparous woman was referred to the outpatient department by her general practitioner following the detection of an abdominal swelling, found incidentally during a routine visit to obtain a cervical smear for cytology. She had no other medical complaints and had not noted any pressure symptoms or systemic disturbance in association with the mass. The previous cervical smears had been normal. She had regular menstrual periods, bleeding for five days in a 28 day cycle. There had been no associated bleeding irregularity, pain or significant weight loss. She was not sexually active and therefore did not use any contraceptives, although she had had an intrauterine contraceptive device inserted for one year, 12 years previously. This was removed following an episode of severe pelvic pain. A left ovarian cyst had also been diagnosed 18 years prior to this referral. The cyst appeared to have resolved spontaneously and no further treatment had been required. She smoked about 20 cigarettes per day and suffered from mild chronic bronchitis. In addition, she was receiving treatment for left lower limb sciatica. General physical findings were normal at presentation. There was no sign of pallor, lymphadenopathy, respiratory or cardiovascular disease. Further examination revealed a nontender, smooth, cystic mass arising from the pelvis which was consistent in size with an 18-week pregnancy. There was no other palpably enlarged organ, no clinical evidence of ascites, and no bruit were heard over the mass. Pelvic examination revealed a mobile, normal sized uterus, separate from, and anterior to the mass. Laboratory investigations performed subsequently were all reported normal. These included estimation of the serum CA125, alpha fetoprotein, carcinoembryonic antigen, human chorionic gonadotrophin and serum carbohydrate antigen C19–9. A full blood count, kidney and liver function tests were similarly normal. Ultrasound scans of the abdomen and pelvis were performed. These did not reveal any focal lesions in the liver although a few gall stones were noted. The kidneys, spleen and pancreas appeared normal. A large cystic mass was seen, arising from the pelvis. It measured 10 × 7 × 18 cm. There were numerous rounded hyper-echoic structures within the cystic mass (Fig. 1). Magnetic resonance imaging (MRI) confirmed the ultrasound findings of a cystic abdomino-pelvic mass. It contained multiple, discrete, globules, each approximately 2 cm in diameter (Fig. 2). The cyst was clearly separate from the other pelvic organs, and the bladder appeared normal. Pelvic ultrasound scan showing the cyst and its contents. MRI scan of the abdomen and pelvis. An exploratory laparotomy was performed through a midline skin incision. A peritoneal aspirate which appeared blood-stained was obtained for cytology. The right ovary containing a smooth-walled ovarian cyst, 18 cm in diameter, was excised along with the corresponding fallopian tube. A biopsy of the contralateral ovary was performed. She made an uneventful recovery and was discharged home a week after the operation, with a four week outpatient follow up appointment to discuss the histology results. The peritoneal aspirate showed blood, a few mesothelial cells and numerous white blood cells, mainly lymphocytes. The macroscopic appearance of the ovarian mass was that of a cystic structure, which contained 1.5 L of serous fluid (Fig. 3). It weighed 205.4 g, with attached fallopian tube at the fimbrial end. The cyst contained 101 uniformly sized lipoid globules each 2 cm in diameter (Fig. 4), nine of which contained coarse hair elements. The cyst wall was 0.4 cm thick. The fallopian tube was unremarkable and measured 6 × 1 cm. No solid areas were seen. The right salpingo-oophorectomy specimen at operation. The right ovarian cyst and its emptied contents. Microscopy confirmed the appearance of a benign cystic teratoma. It was lined predominantly by stratified squamous keratinising epithelium with numerous pilosebaceous units. The underlying connective tissue appeared congested, but there was no evidence of infarction suggestive of a prolonged period of complete torsion of the cyst. There were no immature elements seen, and there was no evidence of malignancy. The globules found within the cyst cavity consisted of sebaceous debris with skin squames and fine hair shafts (Fig. 5). The biopsy specimen from the contralateral ovary was histologically normal. A cut cross-section of an individual spherule showing the progressively softer centre. Benign cystic teratoma is one of the commonest human germ cell tumours and is often found in the ovary in women of reproductive age1. The great diversity in site of occurrence and clinical presentation of teratomas in general occasionally leads to diagnostic difficulty, while the range of unusual to bizarre associated findings has resulted in several reports of novelty value in the world literature2–9. Although a spectrum of ultrasonographic, computed tomography, and magnetic resonance imaging appearances has been reported for benign cystic ovarian teratomas, certain distinct features occur with a degree of constancy1,10–18. These include layering with floating debris or digitate mural protrusions (the ‘dermoid plug’), with hyperechoic calcifications indicating the presence of bone, teeth or other ectodermal derivatives in a predominantly cystic medium. Occasionally, the complex mass is semi-solid with fat-fluid levels. The typical ultrasound features often seen include an axial location, solid mural components, acoustic shadowing due to the hair and sebum within, and hair-fluid levels11,15. The value of magnetic resonance imaging in the management of these tumours is also well recognised10,19. What was quite unusual in this case was the presence of discrete, uniformly sized mobile globules, similar on cut section to chocolate truffles. A similar appearance has been reported in teratomas found in the ovary and mediastinum, but both cases were without spherule formation5,17. The reason for the uniformity in the size of the globules in this case is not known, but it is speculated that each globule was formed by the aggregation of sebaceous matter around a tiny focus of debris, squames or fine hair shaft. The spherules appear to have been modelled into discrete masses rather than remaining as an amorphous mass because of the difference in physical and thermal properties of the material being deposited around each nidus. The spherules appeared to be formed of concentric sebaceous rings with progressively lower densities as the centre was approached. The lower specific gravity compared with the surrounding cyst fluid at body temperature could account for their mobility. It is also possible that fluid collected in the cyst cavity in addition to the insoluble sebaceous material and hairs, as a consequence of venous stasis with the steadily increasing size. Such circulatory compromise is more commonly seen with torsion, and although there was no clinical or histological evidence of complete torsion of the cyst in this case, incomplete torsion or pressure effects due to compression of its vascular supply remain possibilities. In further support of this theory is the fact that the cyst was right sided and torsion occurs more commonly on the right side20. Movements of the cyst wall as a result of peristalsis in small bowel loops may have encouraged the viscostatic aggregation of this sebaceous material, and contact between the rolling aggregates induced uniform spherule formation. We counted 101 spherules at surgery in this case, all evenly rounded. Each nodule was 2 cm in diameter, and had a 3 mm thick outer sebaceous shell. The central core was less dense. Unlike the customary coarse appearance, the hairs seen were of a very fine nature, with the exception of the nine noted earlier. This may further account for the consistent separation of the spherules in the cyst fluid. The presence of hairy balls on ultrasound is suggestive of papillary projections and may indicate a higher likelihood of malignancy. Malignant change is reported in up to 2.8% of benign cystic teratomas, commonly squamous carcinomas21. There was, however, no evidence of malignant change in this case. This phenomenon in the ovary is rarely seen. It may be explained by the occurrence of lipid globules floating in a suspension of sebaceous fluid because of the differential thermal and/or physical properties of the components. Such an appearance has not, to the best of our knowledge, being demonstrated in other tumours. It was termed the ‘truffle sign’ because of its similarity in appearance to chocolate truffles.