Miliary brain metastases from lung adenocarcinoma with EGFR (L858R) and CTNNB1 mutations

Sep 24, 2026

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A 76-year-old man with cough was evaluated by chest CT, revealing a 45-mm lingular mass and transbronchial biopsy-proven adenocarcinoma. Contrast CT and bone scintigraphy confirmed lung, pleura, and bone metastases, staging the disease as left upper lobe adenocarcinoma cT2bN3M1c stage IVB. Oncomine Dx testing identified EGFR (L858R) and CTNNB1 co-mutations, and first-line osimertinib achieved initial improvement. After six months of progression, osimertinib was stopped and carboplatin plus pemetrexed was started, but after three cycles the patient developed dementia and disorientation. Contrast MRI demonstrated miliary brain metastases; whole-brain irradiation was given, yet symptoms rapidly worsened, supporting a role for co-mutations and EGFR-TKI discontinuation.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages2

Reading Time5 min

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Case presentation

Diagnosis and staging

Molecular findings

Treatment course and progression

Neurologic deterioration and imaging

Outcome and implications

DOI: 10.1111/1759-7714.15144 CA SE IMA G E Miliary brain metastases from lung adenocarcinoma with EGFR (L858R) and CTNNB1 mutations Michihiro Kunishige 1 | Eiji Takeuchi 2 1Department of Respiratory Medicine, National Hospital Organization Kochi Hospital, Kochi, Japan 2Department of Clinical Investigation, National Hospital Organization Kochi Hospital, Kochi, Japan Correspondence Eiji Takeuchi, Department of Clinical Investigation, National Hospital Organization Kochi Hospital, 1-2-25 Asakuranishimachi, Kochi city, Kochi 780-8077, Japan. Email: [eijitake1964@icloud.com](eijitake1964@icloud.com) Abstract A 76-year-old man was referred to our hospital with a cough. Chest computed tomography (CT) revealed a 45-mm mass in the lingular segment of the left upper lobe. Transbronchial tumor biopsies showed adenocarcinoma. Contrast-enhanced CT and bone scintigraphy revealed lung, pleura, and bone metastases. The patient was diagnosed with left upper lobe adenocarcinoma cT2bN3M1c stage IVB. A genetic analysis of the primary tumor using the Oncomine Dx Target Test Multi-CDx system revealed positivity for epidermal growth factor receptor (EGFR) (L858R) and CTNNB1 mutations. Based on these findings, the patient was treated with osimertinib (80 mg/day) as first-line therapy. Six months later, the tumor increased in size, indicating progressive disease. Osimertinib was stopped and second-line therapy with carboplatin (area under the curve 5) and pemetrexed (500 mg/m2) was initiated. After three cycles of chemotherapy, the patient developed dementia and disorientation. Contrast-enhanced magnetic resonance imaging of the head showed miliary brain metastases. Miliary dissemination is a rare form of brain metastasis. Miliary patterns of lung metastases have been strongly associated with the EGFR exon 19 deletion. The radiological features of miliary brain metastases of non-small cell lung cancer with the exon 19 deletion have been reported. To the best of our knowledge, this is the first case report of lung cancer with miliary brain metastases and co-mutations of EGFR (L858R) and CTNNB1 . In conclusion, co-mutations of EGFR (L858R) and CTNNB1 and the discontinuation of EGFR-tyrosine kinase inhibitor may contribute to the development of miliary brain metastases. Further case studies are warranted. KEYW ORD S adenocarcinoma of lung, brain metastases, CTNNB1, EGFR, miliary A 76-year-old man was referred to our hospital with a cough. Chest computed tomography (CT) revealed a 45-mm mass in the left upper lobe. Transbronchial tumor biopsies showed adenocarcinoma. CT and bone scintigraphy revealed lung, pleura, and bone metastases. The patient was diagnosed with left upper lobe adenocarcinoma cT2bN3M1c stage IVB. A genetic analysis of the primary tumor using the Oncomine Dx Target Test Multi-CDx system revealed positivity for epidermal growth factor receptor (EGFR) (L858R) and CTNNB1 mutations. Based on these findings, the patient was treated with osimertinib (80 mg/day) as firstline therapy. He achieved clinical improvement and a partial response. Six months later, the tumor increased in size, indicating progressive disease. Osimertinib was stopped, and second-line therapy with carboplatin (area under the curve 5) and pemetrexed (500 mg/m2) was initiated. After three cycles of chemotherapy, the patient developed dementia and disorientation. Contrast-enhanced magnetic resonance imaging of the head showed miliary brain metastases (Figure 1) . The patient was treated with whole brain irradiation; however, his symptoms rapidly progressed and he was transferred to palliative care. Miliary dissemination is a rare form of brain metastasis which is characterized by perivascularly distributed diffuse miliary nodules not accompanied by intraparenchymal invasion. In 1951, Meadow and Alpers described the first case of cancerous encephalitis, now called This is an open access article under the terms of the Creative Commons Attributio

FAQs

What molecular alterations were found in the patient’s primary lung tumor?

Genetic testing using the Oncomine Dx Target Test Multi-CDx system showed positivity for EGFR (L858R) and CTNNB1 mutations.

Which treatments were used first-line and second-line?

First-line therapy was osimertinib (80 mg/day). After progression, second-line therapy consisted of carboplatin (AUC 5) and pemetrexed (500 mg/m2).

How were miliary brain metastases detected and how did the patient respond?

Contrast-enhanced MRI of the head showed miliary brain metastases. Whole-brain irradiation was administered, but symptoms progressed rapidly and the patient was transferred to palliative care.

Sep 24, 2026

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