Neuroendocrine rectal tumour recurrence

Clinical History

In a 42-year-old woman, with a history of lung and breast tumour, anterior resection for neuroendocrine rectal cancer was performed 1 year ago. Now she was admitted to our hospital because of clinically manifest rectal bleeding.

Imaging Findings

The patient underwent a CT scan one year ago which demonstrated a neuroendocrine rectal cancer (Fig. 1). Now she was admitted to our hospital with rectal bleeding, and considering her clinical history it was decided to perform MR imaging. MRI showed multiple nodular solid lesions (at least 10) sized between 1 and 3 cm, involving the lower rectum and the anal canal; they were located in the lumen, in the rectal wall, in the perirectal space and in the recto-vaginal septum. Multiple lymph nodes with a diameter of 14 mm were present in the mesorectum. All lesions had regular contours and showed an intermediate-high signal intensity on T2w images and an early enhancement on T1w images after intravenous gadolinium injection (Fig. 2). On diffusion-weighted images (b value 800) the tumours were detected as hyperintense masses (Fig. 3). The lesions were related to neuroendocrine carcinoma recurrence and the diagnosis was confirmed by histology. A surgical treatment was not performed considering the clinical condition of the patient.

Discussion

Neuroendocrine tumours (NETs) of the distal colon and rectum are also known as hindgut carcinoids based on their common embryologic derivation. Current incidence in USA is approximately 1 in 100,000 [1]. The rectum is the third most common location for gastrointestinal carcinoids next to the small bowel and colon [2].
The most recent WHO classification categorised all gastrointestinal NETs on the basis of clinical-pathological criteria as follows: well-differentiated endocrine tumours, well-differentiated endocrine carcinomas, and poorly differentiated endocrine carcinomas [3].
NETs of the gastroenteropancreatic system are usually sporadic but they may occur in some genetic syndromes such as multiple endocrine neoplasia (MEN) type 1, von Hippel-Lindau syndrome, neurofibromatosis type 1, and tuberous sclerosis [3]. A possible association between carcinoid tumours and other neoplasms (mainly colon, small intestine and endocrine gland cancers) as in the case reported is also described [4].
Carcinoid tumours may grow as either well-defined nodular masses or local relatively uniform areas of rectal wall thickening. Rectal carcinoids smaller than 1 cm and confined to the submucosa have a benign prognosis, whereas tumours larger than 2 cm or those with spread in the muscularis propria are considered malignant. Metastases occur in tumours larger than 2 cm [5].
The symptoms of rectal carcinoids are bleeding, pain or constipation, but generally the patienrs are asymptomatic [2].
NETs of the rectum are usually diagnosed by endoscopy and histological correlation. Cross-sectional imaging plays an integral role in the staging of these tumours. On CT scanning carcinoids may appear as a hypervascular mass or as hypervascular mural thickening in case of small lesions [6]. On MRI, carcinoid tumours presenting as a well-defined nodular mass tend to have homogeneous intermediate signal intensity on T1w images, with a strong early enhancement after intravenous injection of gadolinium, and intermediate-high signal intensity on T2w images; tumors presenting as local rectal wall thickening tend to have intermediate signal intensity on both T1w and T2w images and a strong homogeneous contrast enhancement on T1w.
Surgical resection is the treatment of choice for primary carcinoid tumours and in patients with resectable metastatic disease. Treatment with octreotide or other somatostatin analogues provides symptomatic relief in carcinoid syndrome, although no associated significant improvement in survival or tumour size has been demonstrated [7].

Differential Diagnosis List

Final Diagnosis

Recurrence of neuroendocrine rectal carcinoma.

URL:	https://www.eurorad.org/case/9060
DOI:	10.1594/EURORAD/CASE.9060
ISSN:	1563-4086