Reninoma in an Adolescent Girl: Histopathological Insights with Review of Literature

Background: Reninoma is an uncommon mesenchymal tumor of the kidney. It is characterized by renin secretion and uncontrollable hypertension with associated hypokalemia. Case report: Here we report a case in a 15-year-old girl who presented with refractory hypertension, muscle weakness, and fatigue. Diagnostic workup revealed severe hypokalemia, metabolic alkalosis and elevated plasma renin activity with raised aldosterone levels. Renal artery doppler done to exclude renal artery stenosis, revealed a left sided renal mass. Simple nephrectomy was done and histopathological and immunohistochemical examination were consistent with a diagnosis of reninoma. Electron microscopy revealed renin crystals in the cytoplasm, thus confirming the diagnosis. Conclusion: This report underscores the importance of including reninoma in the differential diagnosis of secondary hypertension in an adolescent. Additionally, insights into histopathology and electron microscopy are important for the diagnosis of reninoma as there are several renal tumors that have renin-secreting activity.