[856] OCT4 Staining in Diagnosis of Micrometastasis in Retroperitoneal Lymph Node Dissections.

Theodore Kieffer, Liang Cheng, Muhammad Idrees. Indiana University, Indianapolis

Background: Immunohistochemical staining with OCT4 is a sensitive and specific marker for seminoma and embrynal carcinomas. Patients with stage I seminoma post orchiectomy may choose surveillance, adjuvant therapy, or retroperitoneal lymph node dissection (RPLND) to manage occult metastasis. RPLND has staging and therapeutic value, and proper staging is extremely important. We developed a study to assess the utility of OCT4 staining in identifying micrometastasis in RPLND in seminoma patients.
Design: Forty-five RPLNDs with primary or metastatic seminoma were identified in the archives. The cases were subdivided into virgin RPLND with clinical suspicion (VRPLND+CS), virgin RPLND without clinical suspicion (VRPLND-CS), and postchemotherapy RPLND (PC RPLND). H&E slides were reviewed and representative blocks were chosen that were initially read as negative or containing multiple benign nodes. Sections were stained with polyclonal goat anti-OCT4 antibody and viewed with light microscopy. Additional positive lymph nodes were identified.
Results: 262 lymph nodes from 45 RPLND cases were reviewed: 13 VRPLND+CS, 11 VRPLND-CS, and 21 PC RPLND. Clinical suspicion was defined as adenopathy or elevated germ cell serum markers. 21 additional positive lymph nodes were identified in 12 cases (Table 1). There was no change in diagnosis after OCT4 immunostaining. The greatest difference between pre OCT4 staining and post OCT4 staining was seen in VRPLND+CS (12.6%) followed by PC RPLND (7.4%) then VRPLND-CS (4.1%).

1 RPLND data

	Metastasis/Total cases		Positive nodes/Total nodes
	Pre-OCT4	Post-OCT4	Pre-OCT4	Post-OCT4
Virgin RPLND with clinical suspicion	11/13 (84.6%)	11/13 (84.6%)	4/79 (5.1%)	14/79 (17.7%)
Virgin RPLND without clinical suspicion	5/11 (45.5%)	5/11 (45.5%)	0/74 (0%)	3/74 (4.1%)
Postchemotherapy RPLND (Clinically evident disease)	18/21 (85.7%)	18/21 (85.7%)	2/109 (1.8%)	10/109 (9.2%)
Total	34/45 (75.6%)	34/45 (75.6%)	6/262 (2.3%)	27/262 (10.3%)

Conclusions: There is a significant difference between the number of positive lymph nodes before and after OCT4 staining (2.3% to 10.3%, respectively) with virgin RPLND with clinical suspicion accounting for most total and proportional additional positive nodes. All differences arose from cases in which positive nodes had already been identified thus there was no change in diagnosis. Multiple cases were identified where single cells had metastasized. We recommend diligence when examining RPLND and routine OCT4 staining for diagnosis of micrometastasis and precise staging especially in patients with adenopathy or elevated serum markers.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 79, Tuesday Afternoon