Presentation
Fever and headaches.
Patient Data
Peripherally enhancing right basal ganglia lesion with extensive surrounding vasogenic edema.
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. Right frontoparietal sulcal effacement, partial effacement of the right lateral ventricle with shift of the midline to the left.
There is dilation of the left temporal horn associated with periventricular FLAIR hyperintensity suggestive of hydrocephalus with transependymal flow of CSF.
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.
A 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.
Conclusion:
Right basal ganglia expansile mass with nodular contrast enhancement does not represent a pyogenic abscess. Atypical infection (especially toxoplasmosis) is a possibility. Glioblastoma may also appear similar. In the setting of the CT chest abnormalities (see later) the most likely diagnosis is, however, a metastasis.
Central right middle lobe lung mass is associated with 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: normal (not shown)
Conclusion:
Right middle lobe lung mass with hilar and subcarinal lymphadenopathy. Likely differential between primary lung cancer and less likely pulmonary TB.
Case Discussion
The patient went on to have both the lung and brain lesion biopsied.
Transbronchial needle aspiration
The smears cell block section show small cells occurring as single cells, in crowded clusters and groups with focal nuclear molding. The tumor cells have high N/C ratio, the nuclei are round to oval and hyperchromatic, a few with nucleoli and scant cytoplasm. Frequent mitoses are noted. The background contains scattered mixed lymphoid cells, foamy macrophages and abundant acellular debris.
By immunohistochemistry the tumor cells are positive for CAM5.2, TTF1 (weak) INSM1 (focal), CD56 and synaptophysin. Ki67 index is 80%
FINAL DIAGNOSIS: Small cell lung cancer
Brain needle biopsy
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 synaptophyin, CD56, and CK7. Focal positive TTF-1 and chrommogranin.
FINAL DIAGNOSIS: Metastatic poorly differentiated neuroendocrine carcinoma
Discussion
A solitary basal ganglia metastasis is unusual and thus, especially in the setting of fevers, the importance of establishing the diagnosis with certainty.
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