Epidermal Inclusion Cyst Of The Ovary: A Rare Case
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M L N Medical College, Allahabad,(India)Email : firstname.lastname@example.org
Epidermoid cysts of the ovary are rare benign, non teratomatous lesions and are usually an incidental finding in hysterectomy specimens (1). They must not be misdiagnosed as mature cystic teratomas of the ovary. Some authors believe that they are monodermal teratomas. Their histogenesis is still uncertain. Some authors believe that these epidermoid cysts arise from the Walthard cell nests, a type of epithelial cell nests. We report here, a case of an epidermoid cyst which was incidentally found in the ovary of a female who was worked up for fibroid uterus.
Epidermal inclusion cyst; monodermal teratoma; Walthard nest
Epidermoid cysts of the ovary are exceptionally rare,(2) benign lesions filled with flakes of keratin and are lined exclusively by mature stratified squamous epithelium. They differ from mature cystic teratomas of the ovary by the absence of skin adnexae and other tissues after thorough sampling. The possibility that some of these lesions are actually mature cystic teratomas in which the skin adnexal components were missed or absent (mature monodermal teratomas), cannot
be totally discounted. Several cases of epidermoid cysts of the ovary have been reported in literature from around the world and almost all these cases have represented incidental findings during the study of a hysterectomy specimen.
A 39 year old female presented with the complaint of increased per vaginal bleed. The patient was investigated. Ultrasonography revealed that she had a fibroid uterus. The patient underwent Total Abdominal Hysterectomy and Right Salpingo-oopherectomy (Table/Fig 1).
Grossly, the uterus and cervix measured 8.5 x 5.5 x 3 cm. The cut surface of the uterus showed an intramural, white, whorled area with a regular endometrial canal. The cervix was apparently healthy. The right ovary and tube measured 4 x 2.5 x 1 cm in size. The cut surface of the ovary showed multiple tiny cystic areas and a central white area measuring 1.5 x 1 .5 cm (Table/Fig 2).
Histological examination of the specimen revealed Leiomyoma uteri and chronic cervicitis. Besides the normal structure of the ovary, one area showed flakes of keratin lined by benign stratified squamous epithelium. Skin adnexae (hair follicles, sebaceous glands etc.) were not present around the flakes of keratin. Based on these histological findings, a diagnosis of ‘Epidermal inclusion cyst of the Ovary’ was made (Table/Fig 3).
‘Epidermal inclusion cyst of the Ovary’ is a rare lesion as has been reported from around the world and almost uniformly represents the incidental findings in the study of hysterectomy specimens. The earliest cases were reported by Nogales and Silverberg in 1976 and they suggested that metaplasia of the coelomic surface epithelium of the ovary was involved in the histogenesis of these lesions. Young and Scully described 3 cases in 1980 and after making a comparative study of these lesions, Walthard nests and epithelial components of Brenner tumours suggested that Epidermoid cysts originate from epithelial cell nests of the type encountered in Brenner tumours. Fan et al, in their series of 8 cases, suggested that ovarian epidermoid cysts represented monodermal and highly differentiated teratomas and should be classified as such (3). They also believed that epidermoid cysts of the ovary are not as rare as the literature suggests and some are probably misdiagnosed as dermoid cysts. Recently, more case reports have been published. Peters et al reported an epidermoid cyst of the ovary in combination with a well differentiated endometrioid adenocarcinoma of the ovary (4). The carcinoma had some foci of squamous metaplasia, but there was no continuity between the wall of the epidermoid cyst and the squamous metaplasia of the carcinoma. The authors suggested that their case highlighted the still unsolved question about the origin of epidermoid cysts and added to the hypothesis that these cysts arose from pluripotent celomic epithelium. Azzena et al described a case in combination with a primary carcinoid tumour of the ovary (5).
The importance of reporting this case is its rare occurrence and to avoid a misdiagnosis of mature cystic teratoma.
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