Paraneoplastic Minimal Change Disease Revealing an Underlying High-Grade Neuroendocrine Carcinoma: A Case Report

Introduction: Paraneoplastic syndromes are clinical manifestations resulting from malignancy-associated factors such as cytokines, hormones, and tumor antigens. Among these, paraneoplastic glomerulopathies represent a significant yet under-recognized group, commonly presenting with nephrotic syndrome. The actual incidence of paraneoplastic nephropathy is likely underestimated. Early recognition is vital, as nephrotic syndrome can precede the diagnosis of an underlying malignancy and prompt earlier oncologic evaluation. Here we present a case of podocytopathy secondary to a neuroendocrine tumor. Case Description: A 68-year-old male with HIV in remission, Hepatitis C treated with Harvoni, hyperlipidemia, CAD, and CKD presented with hypertensive urgency and AKI. BP was 174/81 mmHg; creatinine 6.35 mg/dL (baseline ~1.6–1.8); albumin 3.0 g/dL. A 24-hour urine collection showed 6.6 g of protein. Serologies were positive for Hepatitis C and ANA (1:320). Serum immunofixation revealed faint IgM-lambda restriction. CT chest and PET scan showed abnormal mediastinal lymphadenopathy (MLN). Urine toxicology was positive for cocaine, methadone, and opiates. Renal biopsy showed changes of acute tubular injury/necrosis and negative Congo red staining for amyloid. Electron microscopy identified moderate foot process effacement (~40-50%). The extent of effacement was unconvincing for a primary podocytopathy, more likely secondary forms of podocyte injury. The patient was started on dialysis, lung biopsy done with findings consistent with a high grade small cell type neuroendocrine carcinoma. Patient is planned to initiate treatment. Discussion: Paraneoplastic glomerulopathies are clinically significant but often under-recognized. Minimal change disease (MCD), though classically linked to Hodgkin lymphoma, is increasingly associated with solid tumors. Unlike primary MCD, secondary forms may show partial or atypical foot process effacement on electron microscopy. Recognizing this distinction is crucial to its therapeutic implications: remission of nephrotic syndrome has been observed following successful treatment of the underlying condition. In this case, nephrotic syndrome with abnormal MLN and remission of HIV and hepatitis B raised concern for malignancy, prompting a lung mass biopsy that confirmed the diagnosis.