Neuroendocrine carcinoma

CLINICAL HISTORY

Fifty-two-year old woman with a seven-year history of multiple mainly highly differentiated liver metastases, due to a neuroendocrine tumor. Liver metastases were monitored on contrast-enhanced MRI and abdominal CT (with intravenous contrast and positive oral contrast) for several years. This follow-up scan had also revealed one partly calcified mesenteric lymph node metastasis.

The primary tumor had not been found on endoscopy or octreotide scintigraphy. The patient was asymptomatic and working part time. Disease progression was observed five years after initial diagnosis in terms of slight growth to the liver metastases. The patient remained asymptomatic. The last follow-up scan was performed on a 64-slice CT system, using negative oral contrast and a triple-phase intravenous contrast protocol.

FINDINGS

FIGURE 1. Prior imaging results show multiple liver metastases.
FIGURE 2. Arterial phase of last follow-up CT (protocol above) reveals arterially enhancing (therefore highly vascularized) lesion in distal portion of partly thickened jejunum (A). Small bowel lesion was directly adjacent to the already-known calcified mesenteric lymph node metastases with desmoplastic reaction (B). Imaging patterns prompted readers to suspect a primary neuroendocrine tumor in the small bowel.
FIGURE 3. Prior CT performed with positive oral contrast and venous-phase contrast enhancement demonstrated the partly calcified mesenteric lymph node metastasis (B) but not the primary tumor.

DIAGNOSIS

Histopathology following segmental resection of the jejunum confirmed the imaging-based suspicion. A mainly highly differentiated - but also partly poorly differentiated - neuroendocrine carcinoma was identified.

DISCUSSION

Primary neuroendocrine tumors can be very small and, consequently, easy to miss on general imaging protocols (Prokop M, Galanski M, Van der Molen AJ, Schaefer-Prokop C. Spiral and multislice computed tomography of the body. Stuttgart, Germany: Thieme, 2003). The desmoplastic reaction, in this case a calcified lymph node with a serrated rim, often points to the localization of the primary tumor. Arterial phase intravenous contrast-enhanced imaging may be needed if the bowel wall is thickened and highly vascularized. Negative oral contrast may be better than positive contrast to aid differentiation of the arterially enhancing lesion within the bowel wall. Further indirect signs of neuroendocrine tumors include a retracted mesenterium and distorted bowel loops.

Case submitted by Dr. Patrick Veit-Haibach, a resident at the institute for medical radiology, department of nuclear medicine, University Hospital Zurich.