Single brain metastasis from a minute, well differentiated, but invading beyond the tunica muscularis mucosa rectal carcinoid

We report the case of a 48-year-old woman with small-sized (< 10 mm), highly differentiated, aggressive rectal carcinoid, who developed a solitary distant metastasis to the brain. The primary lesion, initially removed by conventional polypectomy, invaded the mucosa/tunica muscularis mucosa and had positive resection margins. Afterwards, an assessment of 5-hydroxyindoloacetic acid (5-HIAA) 24 h urine excretion revealed a significantly increased level. Thus, a partial rectal resection was performed. Because of constantly elevated carcinoid markers : serum chromogranin A (CGA) and 5-HIAA, a somatostatin receptor scintigraphy was performed, which disclosed a focus of pathological marker accu- mulation in the left frontal area. The pathological finding after neurosurgical excision was meningioma. An unexpected normal- ization of the biochemical markers prompted us to verify this diagnosis. The final histopathological report was a well-differen- tiated neuroendocrine brain metastasis. Our case shows that in well differentiated, of diameter < 10 mm rectal carcinoids, an invasion even beyond the mucosa/tunica muscularis mucosa seems to be an independent factor predicting a malignant metastatic potential of these tumors. Hence, in such cases, behind the endoscopic submucosal resection with ligation device a more radical surgery should be considered. Additionally, a systematic CGA and 5-HIAA follow-up assessment and whole body somatostatin receptor scintigraphy, if necessary, are required. (Acta gastroenterol. belg., 2009, 72, 63-66).