D2-40 immunohistochemistry in the differential diagnosis of seminoma and embryonal carcinoma: a comparative immunohistochemical study with KIT (CD117) and CD30 Modern Pathology (2007) 20, 320–325 Sean K Lau, Lawrence M Weiss and Peiguo G Chu Department of Pathology, City of Hope National Medical Center, Duarte, CA, USA Intern 鄭詩燕

Testis: Germ Cell Tumors Seminoma Nonseminomatous Embryonal carcinoma Yolk sac (endodermal sinus)tumor Choriocarcinoma Teratoma

Germ Cell Tumors Seminoma Nonseminomatous localized to the testis extension to the epididymis, spermatic cord, or scrotal sac Stage I or II II or III Metastasis Lymphatic lymphatic Hematogenous to lung or liver Treatment Radiotherapy Chemotherapy Prognosis good Depend on the tumor type Stage I: Tumor confined to the testis, epididymis, or spermatic cord   •    Stage II: Distant spread confined to retroperitoneal nodes below the diaphragm   •    Stage III: Metastases outside the retroperitoneal nodes or above the diaphragm

Seminoma Age: 15-35y/o 50% of germ cell tumor Painless swelling Dysgerminoma in ovary

Seminoma Bulky masses, sometimes 10 times> the normal testis. Homogeneous, gray-white, lobulated cut surface, usually devoid of hemorrhage or necrosis Mostly the entire testis is replaced. Occasionally, extension to the epididymis, spermatic cord, or scrotal sac

Seminoma

Seminoma Seminoma Cell: large and round to polyhedral and has a distinct cell membrane A clear or watery-appearing cytoplasm A large, central nucleus with one or two prominent nucleoli The cytoplasm contains varying amounts of glycogen. AFP(-) or HCG(-), placental alkaline phosphatase(+), 15%HCG(+) contain syncytiotrophoblasts

Seminoma Low magnification shows clear seminoma cells divided into poorly demarcated lobules by delicate septa. B, Microscopic examination reveals large cells with distinct cell borders, pale nuclei, prominent nucleoli, and a sparse lymphocytic infiltrate.

Embryonal carcinoma 20- to 30-year age group. Grow faster than seminoma Painful More aggressive than seminomas

Embryonal carcinoma Size: smaller than seminoma Usually does not replace the entire testis. The mass is often variegated, poorly demarcated at the margins Punctuated by foci of hemorrhage or necrosis Extension through the tunica albuginea into the epididymis or cord is not infrequent.

Embryonal carcinoma

Embryonal carcinoma The cells: alveolar or tubular patterns, sometimes with papillary convolutions Undifferentiated cells, epithelial appearance Hyperchromatic nuclei with prominent nucleoli. Indistinct cell border, variation in cell and nuclear size and shape, mitotic figures HCG(+), AFP (+)

Embryonal carcinoma undifferentiated cells as well as primitive glandular differentiation. The nuclei are large and hyperchromatic

Introduction Some seminomas : increased nuclear pleomorphism, cell crowding, and lack a lymphocytic infiltrate -> confusion with embryonal carcinoma. Limited biopsy specimen or poor tissue fixation.

Introduction Immunohistochemistry CD 30: Embryonal carcinoma(+), Seminoma(-), Mixed germ cell tumors(+/-) KIT(CD117): Seminoma(+), Embryonal carcinoma(-)

Introduction D2-40 Monoclonal antibody reacts with an oncofetal membrane antigen (M2A) which present in testis fetal germ cells Intratubular germ cell neoplasia, seminoma(+), Embryonal carcinoma(-)

Materials and methods 40 cases of testicular germ cell tumor Age 18-41, mean age: 30 Pure germ cell tumor (26 cases) 19 seminomas, 3 embryonal carcinomas,3 teratomas, 1 yolk sac tumor Mixed germ cell tumors(14 cases) 7 seminomas, 11 embryonal carcinomas, 10 teratomas, 2 yolk sac tumors, and 1 choriocarcinoma.

Materials and methods Immunohistochemical staining: D2-40, KIT, CD30 Xylene (deparaffinized) and ethanol (dehydrated) Slide heating in EDTA buffer(pH8) in pressure cooker Automated immunostainer -> antibody detection, counterstained with hematoxylin and coverslipped.

Result 26 14

Result D2-40 antibody Seminoma -- strong membranous Embryonic carcinoma -- weak, focal, distributed along the apical or luminal surfaces of the cells.

Result (seminoma)

Result (embryonal ca) during an automobile accident when the knees impact the dashboard.

Discussion D2-40 recognizes M2A antigen which present in fetal germ cells, lymphatic endothelium, and mesothelial cells. M2A antigen expression in all seminomas and seminomatous components of mixed germ cell tumors

Discussion Present study: -- D2-40 in pure or mixed seminoma: 100% (26/26), (mixed) embryonal carcinoma 29% (4/14) -- Seminoma: diffuse membrane staining -- Embryonal carcinomas: focal and confined to the apical or luminal surfaces. Marks et al study -- D2-40 in seminomas 98%, embryonal carcinomas 69%.

Discussion Distinction between seminoma and embryonal carcinoma can be made on a morphologic basis using conventional histologic methods. Studies addressing the impact of central histopathologic review of previously diagnosed testicular tumors have demonstrated major discrepancy rates of 4–11%

Discussion Immunohistochemical markers: keratins, KIT, and CD30. Antikeratin antibodies -- Embryonal carcinoma : keratin intermediate filaments -- Seminomas lacked Recent study -- Keratin positive in seminomas 4 to 45% KIT and CD30: more effective immunohistochemical markers

Discussion Previous study KIT expression in seminoma: 100% Present study KIT expression in seminoma: 92% none in embryonal carcinomas or non seminomatous germ cell tumors

Discussion CD30: as a sensitive as well as a specific maker for embryonal carcinoma (93%) Focal CD30 expression has been described in a subset of seminomas Leroy et al CD30 in combination with KIT -- seminoma: KIT(-), CD30(+) impossible -- embryonal carcinoma: KIT(+), CD30(-) impossible

Discussion Present study Sensitivity: D2-40 > KIT in seminomas Specific: D2-40 < KIT in seminomas (4/11 embryonal carcinomas +) D2-40 in seminomas: diffuse and membranous D2-40 in embryonal carcinomas: focal and limited to the apical or luminal surface of the cells.

Summary KIT and CD30: a useful markers that allows for seminoma to be distinguished from embryonal carcinoma. Although a highly sensitive marker of seminomas, focal D2-40 immunoreactivity can be seen in a subset of embryonal carcinomas, thus limiting the practical value of this marker for discriminating between these particular malignancies.