PMC4355812_01
(a) T1-axial MRI with contrast and (b) T2-axial Flair MRI performed at initial encounter demonstrate a minimally enhancing mass in the left cerebellopontine angle.
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The patient was counseled as to the different treatment options for a presumed vestibular schwannoma with repeat imaging performed at our institution and chose surgery (Figure 1).
(a) T1-axial MRI with contrast and (b) T2-axial Flair MRI demonstrating enhancing mass in the left cerebellopontine angle 8 weeks later. (c) Post-operative whole body positron emission tomography demonstrating increased uptake in the right lower quadrant corresponding to the small intestine.
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A repeat MRI revealed the mass had increased to 35 mm with mass effect on the pons, superior, middle, and inferior cerebellar peduncles with associated edema (Figure 2). Post-operatively, the patient underwent a whole body PET scan, which demonstrated high FDG activity in the location of the known residual left CPA mass, as well as an additional hypermetabolic mesenteric lesion abutting the ileum and ascending colon in the right lower quadrant (Figure 2).
Pathology of the fragmented CPA tumor mass demonstrated poorly differentiated neuroendocrine carcinoma (small cell). (a) The tumor was highly cellular with tumor cells demonstrating a high nuclear to cytoplasmic ratio and molded nuclei (64x). (b) Higher magnification revealed characteristic finely granular, "salt and pepper" chromatin and frequent mitoses (254x). Both photomicrographs are of an H&E stained section. A Ki-67 proliferation index was high, and neoplastic cells were positive for cytokeratin, synaptophysin, and CD56 (not shown).
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The final pathology report identified the CPA lesion as a poorly differentiated small cell neuroendocrine carcinoma and was confirmed by positive immunostaining of the tumor cells for cytokeratin CAM 5.2, synaptophysin, and CD56 and a high proliferative index (Figure 3).
(a) T1-axial MRI with contrast and (b) T2-axial Flair MRI demonstrating interval decrease in size of previously identified enhancing mass in the left cerebellopontine angle after resection.
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He underwent whole brain radiation therapy followed by chemotherapy and at last follow-up postoperatively has continued to show signs of improvement (Figure 4).