A 58 years female patient with cerebral metastases from pulmonary adenocarcinoma of the right upper lobe presented after a surveillance MRI showed progression of her disease. She was initially diagnosed with adenocarcinoma 4 years earlier, confirmed after a bronchoscopic biopsy and staged: cT1a (0.6 cm) cN2 (station 4R) cM1b (brain metastases), stage IV (according to the TNM 7th edition), without EGFR mutation or ALK/ROS1 rearrangement, PD-L1 negative :cT1a cN2 cM1c (brain metastases), stage IVB (according to TNM 8th edition) With KRAS mutation (G12S, exon 2) and TP53 (C275S, exon 8), without ERBB2 and BRAF mutation. Initial cerebral imaging was suggestive of metastatic disease.
Radio-chemotherapy with 4 cycles of cisplatin-pemetrexed from 15.01.2018 to 19.03.2018, with concomitant radiotherapy in the right upper lobe and mediastinum with a total dose of 66 Gy (in 33 fractions of 2 Gy) from 12.02.2018 to 30.03.2018, and on the 12.10.2018, stereotactic radiotherapy for brain metastases, with a dose of 20Gy in single fraction for each was done.
The patient was followed with surveillance MRI scans every 2–3 months. Her most recent surveillance MRI showed increase of two treated lesions, one in the right frontal lobe and one in the right parietal lobe, suggestive of radionecrosis, and a 2-month control was recommended according to the multidisciplinary tumor board. The 2-month control MRI showed an increase in size of the right frontal lesion with a soft tissue component with contrast enhancement in its posterior part, whose perfusion (nrCBV = 2.3, nrCBF = 2.8) and spectroscopy (Cho/Cr ratio = 2.9) suggest the persistence of tumor residue in this region (Fig. 1).
A 18F-FET PET/CT was performed to further characterize these changes and showed a heterogeneous and low to moderate uptake of the radiotracer at the level of the right anterior frontal lesion, whose quantitative analysis (maximum tumor-to-brain ratios = 2.2, cumulative time-activity curve [TAC]) was in favor of a radionecrotic lesion (Fig. 1). No significant radiotracer uptake was seen in the other metastatic lesions treated by radiosurgery.
In this context, her case was re-discussed at the multidisciplinary meeting for brain metastases where a surgical resection of the right frontal lesion was proposed.
Histology analyses of excisional biopsies of the dura matter and of the lesion showed metastasis of her initial adenocarcinoma with partly calcified dura mater with chronic inflammatory reaction and foreign bodies with no metastatic lesions in the dura matter.