Presentation
Known metastatic carcinoid with ACTH secretion. Bilateral adrenalectomy.
Patient Data
MRI of the brain demonstrates widespread abnormal enhancement, with multiple cerebral ring enhancing masses, dural thickening and enhancement as well as nodular enhancement of the pituitary and infundibulum.
The patient went on to have a biopsy of the frontal lesion.
Histology
MICROSCOPIC DESCRIPTION: The section shows fragments of cerebral tissue containing multiple localized deposits of tumor tissue, which appear to be adjacent to small blood vessels. The tumor deposits vary in size and shape, with the largest ones showing central necrosis. The tumor is cellular, composed of crowded elongate cells with oval nuclei. There are occasional rosettes or tubules surrounded by tumor cells. Tumor cell nuclei show generally granular nucleoplasm and, frequently, small nucleoli. There are scattered mitotic figures at a rate of 20/50 hpf. The Ki67 index is approximately 30% of tumor cells.
The neuroendocrine nature of the cells is confirmed with positive cytoplasmic staining for chromogranin, synaptophysin and CD56. Staining for TTF-1 shows a very occasional single tumor cell nucleus positive. About 30% of tumor cells show moderately strong staining for ACTH. Cells are negative for somatostatin.
The features are those of metastatic neuroendocrine tumor, lacking morphologic features of small cell carcinoma. Applying criteria for neuroendocrine tumors described in the WHO Classification of Tumors of the Digestive System, Bosman et al, IARC, Lyon, 2010, this tumor would be categorized in the "neuroendocrine tumor grade 3" group. In the 2004 WHO categorization of lung tumors, the terminology would be "atypical carcinoid".
FINAL DIAGNOSIS: Left frontal tumor - metastatic neuroendocrine tumor (G3) showing evidence of ACTH production.
Case Discussion
This case illustrates widespread intracranial metastases from a neuroendocrine tumor.
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