[630] Should Mesenteric Tumor Deposits Be Included in Staging of Small Intestine Neuroendocrine Tumors?

Raul S Gonzalez, Eric H Liu, M Kay Washington, Chanjuan Shi. Vanderbilt University Medical Center, Nashville, TN

Background: Small intestine neuroendocrine tumors (SI-NETs) are capable of widespread metastases before the primary tumor causes clinical symptoms. They have a propensity to spread to lymph nodes (LN) and the liver. They also can give rise to mesenteric tumor deposits (MTDs), though MTDs are not included in the current American Joint Committee on Cancer (AJCC) staging system for SI-NETs, and whether these MTDs are harbingers of distant metastases is unknown.
Design: Seventy-three SI-NET resections were identified in our files with slides and radiographic follow-up available. Each case was assessed for the presence or absence of LN metastases and MTDs, lymphovascular invasion (LVI), and liver metastases (pathologic and/or radiologic). AJCC T-stage was also noted. MTDs were defined as discrete mesenteric tumor nodules > 1mm with an irregular growth profile. Similar lesions clearly resulting from extranodal extension or direct contiguous spread by the primary lesion were excluded.
Results: Forty-four of the 73 SI-NET cases had MTDs (60%), which were typically adjacent to a large blood vessel and entrapping nerves. MTDs were significantly associated with LN metastases, liver metastases, LVI, and pT3 or pT4 disease (see table). Six cases (8%) had positive LNs and liver disease, but no MTDs, while 4 cases (5%) had MTDs and liver mets, but no LN disease. There were 9 cases with resected liver mets and no residual liver disease on post-surgical imaging; 5 had both LN mets and MTDs, and 4 had LN mets but no MTDs. All 4 cases with MTDs and no LN disease had residual liver disease on imaging (typically multiple lesions), while 4 of the 6 cases with LN disease and no MTDs had no residual liver disease on imaging, and the other 2 had quantifiable, rather than innumerable, lesions.

 MTD presentMTD absentP-value
LN metastases38/44 (86%)18/29 (62%)0.0236
Liver metastases24/44 (55%)6/29 (21%)0.0070
LVI41/44 (93%)17/29 (59%)0.0007
pT3 or pT440/44 (91%)17/29 (59%)0.0029



Conclusions: MTDs are present in the majority of cases of SI-NET, and they are associated with LVI, LN and liver metastases, and advanced T-stage. A proportion of cases where MTDs are present but no LN disease is identified microscopically have liver metastases, and patients with MTD may be less amenable to surgical cure of liver disease. Given the above findings, we suggest that MTDs may have a place in the staging summary for SI-NETs, perhaps as analogous to LN disease.
Category: Gastrointestinal

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 96, Monday Morning

 

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