[682] SATB2 Is a Highly Sensitive Marker for Hindgut Well-Differentiated Neuroendocrine Tumors

Zhongwu Li, Lixin Zhou, Kaiyong Mei, Ling Jia, Qiang Kang, Miao Zhang, Dengfeng Cao. Peking University Cancer Hospital, Beijing, China; Guangzhou Medical College, Guangzhou, China

Background: Well differentiated neuroendocrine tumors (WDNETs) most commonly involve gastrointestinal (GI) tract, lung and pancreas. WDNETs often show similar morphology and determination of their origin in metastatic sites mainly relies on immunohistochemical markers. CDX2, TTF1 and PDX1 are relatively sensitive markers for WDNETs from midgut, lung and pancreas, respectively. However, there is no sensitive marker for hindgut (distant 1/3 transverse colon to rectosigmoid) WDNETs, which account for approximately 2/3 colorectal WDNETs. Here we investigated a novel marker SATB2 for its diagnostic utility in hindgut WDNETs.
Design: 81 WDNETs from GI tract were included (esophagus 10, stomach 11, small intestine 7, appendix 3, colon 6, rectum 44). One paraffin block from each case was used for immunostaining using a SATB2 monoclonal antibody. To test SATB2 specificity, we also included 43 WDNETs from other sites (pancreas 19, lung 19, mediastinum 5). Immunostains for CDX2 and TTF1 were also performed in all 124 WDNETs for comparison. Only nuclear staining was considered positive for these markers. The percentage of tumor cells stained was semi-quantitatively scored as 0 (no tumor cells stained), 1+ (1-25%), 2+ (26-50%), 3+ (51-75%), and 4+ (>75%).
Results: SATB2 staining was observed in 2/10 esophageal (1+, 4+), 0/11 gastric, 0/7 small intestinal, 1/3 appendiceal (4+), 0/4 right colonic, 0/1 transverse colonic at splenic flexure (TCSF), 1/1 sigmoid colonic (2+), 40/44 rectal (primary 36/40, metastatic 4/4; 1+ in 1, 2+ in 1, 3+ in 1, 4+ in 37), 5/19 pulmonary (primary 3/13, metastatic 2/6; 1+ in 1, 2+ in 2, 4+ in 2), 1/19 pancreatic (2+ in 1/10 primary, 0/9 metastatic), 0/5 mediastinal WDNETs. CDX2 staining was seen in 1/10 esophageal (1+), 3/11 gastric (all 2+), 1/7 small intestine (4+ in 1/1 ileal, 0/6 duodenal), 2/3 appendiceal (2+,3+), 3/4 right colonic (all 4+), 1/1 TCSF (4+), 1/1 sigmoid colonic (4+), 2/44 rectal (2+ in 2/40 primary, 0/4 metastatic), 1/19 pulmonary (4+ in 1/13 primary), 4/19 pancreatic (2/10 primary, 2/9 metastatic; 2+ in 1, 4+ in 3), and 0/5 mediastinal WDNETs. TTF1 staining was seen in 1/10 esophageal (2+), 1/11 gastric (1+), and 9/19 pulmonary (primary 3/13, metastatic 6/6;3 in 1, 4+ in 8) WDNETs and was negative in other WDNETs. The sensitivity and specificity of SATB2 for hindgut WDNETs is 89% and 88%, respectively.
Conclusions: SATB2 is a highly sensitive marker for hindgut WDNETs and is much more sensitive than CDX2. SATB2 should be included in the immunohistochemical panel for determining the primary site of a metastatic WDNET.
Category: Gastrointestinal

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 117, Tuesday Afternoon

 

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