# Triple reversal phenomenon in EGFR-mutant lung adenocarcinoma with prostate metastasis following hepatocellular carcinoma: a rare Case Report with diagnostic and therapeutic implications

## TL;DR

A rare case of lung cancer metastasizing to the prostate, misdiagnosed as liver or prostate cancer, highlights the need for precise testing and targeted treatment.

## Contribution

Reports a rare triple reversal in cancer diagnosis and treatment, emphasizing the importance of molecular profiling in complex metastatic cases.

## Key findings

- Lung adenocarcinoma with EGFR mutation metastasized to the prostate, not the lung.
- Molecular testing confirmed EGFR L858R mutation, guiding effective osimertinib therapy.
- The case highlights the need for repeat biopsies and multidisciplinary evaluation in atypical presentations.

## Abstract

Non-small cell lung cancer harboring EGFR mutations is responsive to targeted therapies such as Osimertinib. Although metastasis from lung cancer to the prostate is exceedingly rare, we present a rare case of prostatic metastasis from lung adenocarcinoma in a patient with a history of hepatocellular carcinoma (HCC) and no evidence of a primary lung lesion.

A 64-years-old male with chronic hepatitis B and a history of hepatocellular carcinoma (HCC) diagnosed in 2014 presented in 2023 with elevated carcinoembryonic antigen (CEA) levels. Initial imaging revealed isolated bone metastasis, initially presumed to be recurrent HCC. Given the long interval since diagnosis, a bone biopsy was performed, unexpectedly showing adenocarcinoma. Subsequent PET-CT identified a prostatic lesion without pulmonary abnormalities, leading to an initial diagnosis of metastatic prostate cancer. Prostate biopsy, however, revealed features consistent with lung adenocarcinoma. Molecular testing detected an EGFR exon 21 L858R mutation, confirming metastatic lung adenocarcinoma. The patient responded favorably to osimertinib therapy.

This case illustrates a rare instance of prostatic metastasis from EGFR-mutant lung adenocarcinoma and emphasizes the critical role of repeat biopsy, molecular profiling, and multidisciplinary evaluation in atypical metastatic presentations. The diagnostic process involved a “triple reversal” phenomenon, revising initial misdiagnoses of recurrent HCC and primary prostate cancer to metastatic NSCLC. Targeted therapy with osimertinib was effective, underscoring the importance of precision oncology in managing complex metastatic disease.