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A: Initial chest CT that visualizes the 2.8 cm lung mass in the left upper lobe. B: Initial brain MRI with 3 x 2.5 cm mass.
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The CT scan of the chest showed a spiculated left apical lung mass measuring 2.8 x 1.6 cm and a 5.5 mm nodule in the left lower lobe, concerning for a malignant process (Fig. 1A). The brain MRI revealed multiple peripherally enhancing lesions in the left temporal lobe measuring 3 x 2.5 cm along with extensive vasogenic edema (Fig. 1B).
A: Repeat Chest CT showing markedly increased mass now measuring 4.3 cm. B: MRI of brain one month after initial MRI showing enlarging brain mass measuring up to 3.9 cm from previously measured 3 cm lesion with extensive surrounding edema.
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AFB and fungal stains were negative and no organism was isolated on tissue culture, leaving the underlying etiology unclear. A PET CT scan performed a couple weeks later showed a metabolically active left lung mass that had significantly increased in size to 4.3 cm (Fig. 2A) accompany by multiple new metabolically active parenchymal and pleural nodules in the left upper lobe of the lung, raising further concerns for malignancy. The repeat brain MRI revealed enlarging left posterior temporal lobe brain mass now measuring 3.9 x 3 x 2 cm with extensive surrounding vasogenic edema and mass effect, as well as new ring enhancing mass in the right occipital lobe (Fig. 2B).
N. beijingensis visualized on the GMS stain from the brain pathology. This isolate was not able to be seen on the brain abscess gram stain and AFB stain.
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Grocott-Gomori's methenamine silver (GMS) stain of brain tissue revealed numerous filamentous organisms (Fig. 3) consistent with Nocardia infection.