Harano Kenichi, Ando Masashi, Sasajima Yuko, Yunokawa Mayu, Yonemori Kan, Shimizu Chikako, Tamura Kenji, Katsumata Noriyuki, Tsuda Hitoshi, Fujiwara Yasuhiro
Breast and Medical Oncology Division, National Cancer Center Hospital, Tokyo, Japan.
Case Rep Oncol. 2012 Sep;5(3):671-5. doi: 10.1159/000337281. Epub 2012 Dec 20.
Yolk sac tumor (YST) is a rare malignant tumor originating from germ cells. YST normally originates from the gonads, rarely occurring in extragonadal sites. We report a 35-year-old man with YST arising in the omentum, which is the first reported case of a primary YST of the omentum in an adult male. The patient presented to the community hospital with abdominal distension. A CT scan showed thickening of the omentum with ascites. The patient underwent open biopsy of the omental mass. The Pathology Department of the hospital could not make a definitive diagnosis at that time, and the tumor was considered a cancer of unknown primary (CUP) origin with features of primary colorectal cancer based on the immunohistochemistry (IHC) findings of the biopsy specimen (CK7-/CK20+ and CDX-2+). He was then referred to our hospital. We found that serum α-fetoprotein was abnormally elevated to 7,144 ng/ml (normal <10.0), and reevaluation of the biopsy specimen revealed microcystic or reticular patterns of tumor cells with Schiller-Duval bodies typical of YST. The present case suggests that IHC is a very useful diagnostic tool for subtyping CUP but should be interpreted in the context of clinical and morphological findings.
卵黄囊瘤（YST）是一种罕见的起源于生殖细胞的恶性肿瘤。YST通常起源于性腺，很少发生在性腺外部位。我们报告了一名35岁男性，其卵黄囊瘤发生于大网膜，这是首例报道的成年男性原发性大网膜卵黄囊瘤病例。该患者因腹胀就诊于社区医院。CT扫描显示大网膜增厚并伴有腹水。患者接受了大网膜肿物的开放性活检。当时医院病理科无法做出明确诊断，根据活检标本的免疫组化（IHC）结果（CK7-/CK20+和CDX-2+），该肿瘤被认为是原发性不明的癌症（CUP），具有原发性结直肠癌的特征。随后他被转诊至我院。我们发现血清甲胎蛋白异常升高至7144 ng/ml（正常<10.0），对活检标本的重新评估显示肿瘤细胞呈微囊状或网状结构，并伴有卵黄囊瘤典型的席勒-杜瓦尔小体。本病例表明，免疫组化是CUP亚型诊断的非常有用的工具，但应结合临床和形态学表现进行解读。
