Sebaceous Adenoma Arising in a Mature Cystic Teratoma in a Middle-Age Woman: A Case Report

Introduction

Mature cystic teratomas are common neoplasms of ovary accounting for 20% all ovarian tumors and 95% of ovarian germ-cell tumors. The incidence of malignancy is quite low, ∼1%–2%.^1,2 Sebaceous-gland neoplasms in mature cystic teratomas are an exceedingly rare occurrence. To date, only 4 cases of sebaceous adenoma have been reported.^3,4 It is mainly seen in middle-age and elderly patients. ⁵ Adequate sampling of the tumor is essential. Another case of sebaceous adenoma arising in mature cystic teratoma is reported in this article.

Case Report

A 42-year-old woman presented in the emergency department with sudden pain in her abdomen and vomiting. Ultrasonographic examination showed large, predominantly cystic, bilateral adnexal masses, measuring 7.1×6.1 cm and 6.4×5.8 cm, with a highly echogenic component. Both ovaries were not separately defined. The possibility of a bilateral dermoid cyst was suggested by the radiologist.

The patient underwent exploratory laparotomy with a hysterectomy and bilateral salpingo-oophorectomy. The patient's postoperative course was uneventful, and she was discharged from the hospital on day 5 after surgery. The left ovarian mass measured 8×6×3.5 cm and the left ovarian mass measured 7.2×6.5×5.0 cm. The outer surface was tan and smooth. Cut sections of both ovaries were partly solid and partly cystic. Multiloculated cysts filled with cheeselike material and hairs were seen. Slides were prepared, stained with hematoxylin-eosin, and seen under the light microscope.

Sections from the cystic areas showed a lining of keratinizing stratified squamous epithelium, including sebaceous glands, sweat glands, and hair. Neural tissue, respiratory and gastric epithelium, fat, bone, and thyroid follicles were also identified.

One of the sections taken from the solid area in the left-sided dermoid showed glands arranged in lobular architecture (Figs. 1 and 2). They were lined by dual cell lining, showing well-differentiated central, larger, mature cells with vacuolated cytoplasm, and peripheral, smaller, less-differentiated, basaloid or germinative cells. A diagnosis of sebaceous adenoma arising in mature cystic teratoma was made.

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FIG. 1.

Section shows pseudostratified respiratory epithelium, adipose tissue, and lobules of sebaceous glands (hematoxylin and eosin, original magnification ×100).

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FIG. 2.

The glands contain large vacuolated cells in the center and basaloid type cells at the periphery (hematoxylin and eosin, original magnification ×100).

Discussion

Monodermal neoplasias are uncommon in mature cystic teratomas, probably occurring in ∼2% of all cases. The most common malignant change in cystic teratoma is squamous-cell carcinoma, followed by carcinoid tumor and adenocarcinoma. ¹ Benign tumors have also been described, and sebaceous adenoma is one of them. It is a very rare entity. Its morphologic appearance and clinical behavior is similar to the homonymous somatic tumor, that is, a sebaceous adenoma of the skin. However, these tumors are of germ-cell origin according to a genotypic standpoint. This view is supported by microdissection-based analysis, which shows that these tumors have a genotype identical to that of a teratoma.^1,6 This indicates that the biologic properties and clinical behavior of these tumors is determined by the phenotype of the tumor rather than its histogenesis.

To date, only 4 cases of sebaceous adenoma in dermoid cysts have been reported. Unlike the patient in this current report, each of the other patients had a unilateral dermoid cyst, which is, in fact, a common occurrence; the incidence of bilateral dermoid cysts is 10%–15%.^3,4 All of the cysts were indolent. None of them recurred or metastasized.

Dermoid cysts with epithelial neoplasms are rarely found in young women. Over three quarters of the patients are >40 years of age, with the average age being 50, as also was seen in the patient described here. ⁵

Because of rarity of this lesion, it may be missed by a pathologist. It is also important to distinguish it from sebaceous carcinoma, as the two entities have different clinical characteristics and development. The distinguishing features are absence of cytological atypia, capsular and vascular invasion, necrosis, and hemorrhage. ⁵ The presence of a sebaceous carcinoma usually indicates a poor prognosis for a patient. To avoid missing the diagnosis, any thick area in the wall of a dermoid cyst must be selected and sectioned for histologic analysis. ⁵

Conclusions

In conclusion, sebaceous adenoma is an extremely rare occurrence in benign cystic teratoma. Its development and clinical outcome is that of a benign tumor. Surgery is curative, and further treatment is not required.