Presentation
Febrile illness and headache. Right basal ganglia rim enhancing lesion with surrounding edema and mass effect.
Patient Data
A vividly enhancing right basal ganglia mass is present, surrounded by abundant vasogenic edema with resultant positive mass effect.
Within the right basal ganglia, there is a mass which demonstrates predominantly peripheral nodular contrast enhancement. This is embedded within a region of expansile FLAIR/T2 hyperintensity involving the right basal ganglia and thalamus extending into the right cerebral peduncle and right side of the midbrain. There is further extensive surrounding high T2/FLAIR signal within the white matter of the right frontoparietal region and right temporal lobe, in keeping with vasogenic edema with mass effect. The enhancing wall of the mass demonstrates low ADC and markedly elevated CBV. No central restricted diffusion. Small foci of susceptibility associated with lesion may represent blood products. MR spectroscopy demonstrates reversal of the choline/creatine ratio, depressed NAA and elevated lactate.
There is dilation of the left temporal horn associated with periventricular FLAIR hyperintensity suggestive of hydrocephalus with transependymal flow of CSF.
Small region of encephalomalacia and gliosis in the left superior frontal gyrus. No other lesions demonstrated. Partial empty sella noted. Incidental developmental venous anomaly in the right hemipons.
Chest: Central right middle lobe lung mass measures approximately 33 mm. Associated partial collapse of the right middle lobe. The lesion abuts the inferior surface of the minor fissure. The left lung is clear. The pleural spaces are clear. Right hilar and subcarinal lymphadenopathy. No pericardial effusion. No axillary lymphadenopathy.
Abdomen/Pelvis: The liver, kidneys, spleen, adrenals and pancreas are unremarkable. No abnormality of the unenhanced small and large bowel is identified. No free intraperitoneal fluid or extraluminal gas. No intra-abdominal lymphadenopathy. No concerning focal osseous abnormality is identified. Bilateral L5 pars defects with associated grade 1 L5/S1 anterolisthesis.
Conclusion Right middle lobe lung mass with hilar and subcarinal lymphadenopathy. Likely differential between primary lung cancer and pulmonary TB.
Case Discussion
The patient went on to have a biopsy of the basal ganglia lesion.
Histology
Biopsy shows extensive necrosis plus cohesive nests and sheets of atypical cells that are well demarcated from the adjacent brain parenchyma.
The cells have pleomorphic, hyperchromatic nuclei with a high nuclear to cytoplasmic ratio and moderate amounts of eosinophilic cytoplasm. There are numerous mitoses and apoptotic bodies. The cells have granular chromatin, though scattered cells with large nucleoli are also seen. There is no gland formation and no pigment is seen.
Tumor cells are positive synaptophysin, CD56, and CK7. Focal positive TTF-1 and chromogranin
FINAL DIAGNOSIS: metastatic poorly differentiated neuroendocrine carcinoma
Discussion
This is an unusual location for a solitary metastasis, more typical of cryptococcosis. The differential includes other atypical infections, a high-grade glioma (GBM) and even lymphoma. The lack of non-enhancing tumor, the nodular but heterogeneous enhancing component and lack of central diffusion restrictions are all somewhat helpful, but the most helpful finding is the lung mass.