Complete remission of membranous nephropathy in a patient with lung adenocarcinoma treated with erlotinib.

WHAT IS KNOWN AND OBJECTIVE: Membranous nephrotic syndrome is one of the most commonly seen paraneoplastic nephropathies.

CASE DESCRIPTION: We describe a 59-year-old man who was referred with massive unilateral pleural effusion and was subsequently diagnosed with lung adenocarcinoma. Routine physical and laboratory examinations revealed lower limb oedema, hypoproteinaemia and proteinuria. Examination of a kidney biopsy aspirate confirmed the diagnosis of membranous nephropathy. Aetiological investigations of the kidney pathology ruled out causes other than paraneoplastic nephropathy. Since an epidermal growth factor receptor mutation was identified by analysis of the exfoliated tumour cells in pleural effusion, erlotinib was administered, without further treatment of the membranous nephropathy. Upon control of the patient's lung cancer, the membranous nephropathy completely disappeared, and at the time of this writing, had not recurred over a 4-year follow-up period.

WHAT IS NEW AND CONCLUSION: For patients with EGFR-mutation-positive lung adenocarcinoma associated with paraneoplastic membranous nephropathy, erlotinib might serve as a treatment option for both the tumour and the membranous nephropathy.