卵巢皮样囊肿(Dermoid Cyst)CT病例图片影像诊断分析

女性生殖系统   2010-05-20

 

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 Clinical History(临床病史): 76岁老年女性发现右下腹无痛性肿块,活动度差。

76-year-old female with a large non-tender, immobile mass in right lower quadrant. 

Findings(影像所见): 轴位CT平扫显示盆腔内大小约6 cm x 8cm 低密度肿块影,肿块左前壁可见钙化成分。乙状结肠和直肠壁可见增厚。

Axial CT without contrast (due to acute renal failure) demonstrates 6 cm x 8cm hypodensity in the pelvis (7cm high - from bottom of sacrum to mid-femoral head). The mass contains a rim of calcification along its left anterior wall. The rectosigmoid and rectum walls are also thickened.

Diagnosis(诊断): 皮样囊肿或良性囊性畸胎瘤

Dermoid cyst or benign cystic teratoma.

Discussion(讨论): 卵巢畸胎瘤是卵巢生殖细胞肿瘤中常见的一种,来源于生殖细胞异常增生所至,属于一种生长在卵巢组织中由生殖细胞异常增生、集聚形成的肿瘤。因为生殖细胞中含有人体外胚叶、中胚叶和内胚叶三种组织成分,所以瘤子里会有毛发、油脂、皮肤、牙齿、骨片等外胚叶组织,也可能含有中胚叶或内胚叶组织如肌肉、胃肠、甲状腺组织等。

  卵巢畸胎癌的种类有好几种,包括成熟畸服癌和未成熟略股瘤等。其中97%是囊性成熟畸胎瘤,又叫皮样囊肿。皮样囊肿是最常见的种类之一,占所有卵巢肿瘤的10%-20%,占生殖细胞肿瘤的85%-97%。因它与妊娠无关,所以卵巢畸胎瘤可发生在任何年龄,新生儿、青少年、中年或老年人均可患此病,但80%-90%为20-40岁的生育期女性,在卵巢肿瘤患者中约占1/ 4-1/3。

  卵巢囊性成熟畸胎瘤一般是中等大小多为一侧,12%为双侧,外表是圆形或椭圆形,被一层光滑的包膜所包含,囊壁质韧,多为单房,囊腔里最多见的是毛发团和油脂,也常有牙齿和骨片。这些组织分化成熟,所以肿瘤大部分是良性的,大约有2%发生恶变。   极少数的未成熟性畸胎瘤,属于恶性肿瘤,它们为恶性生殖细胞肿瘤,具有复发和转移的潜能。肿瘤多为实性,其中可能有囊性区域。瘤内组织不像正常组织,细胞分化不好,有转移、侵蚀、种植的特性。此病好发于青少年及儿童。

  一般说来未成熟性畸胎瘤的预后效果较差,手术无法保证彻底、干净地消灭它,有复发的危险。而良性畸胎瘤的预后较好,良性发生恶变的可能性仅为2%-3%,不影响卵巢功能,手术后月经正常,受孕率正常,不存在复发的问题。

中英文非一一对应关系(Non-correspondence between the Chinese and English)

Dermoid cysts are benign germ cell tumors that affect females of any age, but occur most frequently in patients that are between the ages of 10 and 30 years old. They are the most common ovarian neoplasm, accounting for 10-25% of ovarian tumors, and are bilateral in 15-25% of the cases. They consist of mature ectodermal components including bone, teeth, and hair.

A dermoid cyst can present as an abdominal or pelvic mass, but is more often detected radiographically. CT characteristically shows a complex-appearing cystic mass with a smooth, well-defined surface and a focus of calcification, usually resembling a tooth. The sebaceous contents are the same attenuation as fat. On ultrasound, fluid-fluid levels representing a hairball are common, and the "tip of the iceberg" sign shows an "echogenic mass that fades into acoustic shadowing due to sound absorption." Plain films confirm calcification in the mass.

Despite their benign nature, dermoid cysts are usually surgically removed, because torsion, perforation, infection, and rarely, rupture and chemical peritonitis complicate them. Malignant transformation, generally into invasive squamous cell carcinoma, occurs in 1-2% of the cases. It begins as Rokitansky's protuberance, a partially-solid nipple-like nodule that penetrates the capsule of the tumor. Progressive growth leads to invasion into the bladder, bowel, or pelvic wall, and sometimes, distant metastases.

References(参考文献):
Brant WE and Helms CA. Fundamentals of Diagnostic Radiology. 2nd ed.
Lippincott, Williams & Wilkins, Philadelphia; 1999:822, 865-66.

Kido A, Togashi , Konishi I, Kataoka ML, Koyama T, Ueda H, Fujii S, and Konishi J.
Dermoid cysts of the ovary with malignant transformation: MR appearance. AJR 172(2):445-9, 1999. 

Occhipinti KA, Frankel SD, and Hricak H. The ovary. Computed tomography and magnetic
resonance imaging. Radiol Clin North Am 31(5):1115-32, 1993.

(参考来源:,uhrad.com,作者:胡玉川编译)
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