Paraneoplastic Hypercalcaemia as a Cause of Unexplained Renal Impairment in a Patient With Seminoma: A Case Report

Abstract

A 44-year-old otherwise healthy male who had undergone left high inguinal orchidectomy, with histopathology suggestive of classical seminoma, was referred to the authors’ oncology centre for evaluation of persistently deranged renal function tests and initiation of chemotherapy. They had a large retroperitoneal mass encasing their left kidney and their creatinine was 4.2 mg/dL. Even 1 week after double J stenting, they had persistently elevated creatinine of 3.1 mg/dL, which was precluding their curative chemotherapy with bleomycin/cisplatin/etoposide regimen. In a desperate situation, to prevent further progression of disease, pre-phase chemotherapy with carboplatin and etoposide was considered. In anticipation of tumour lysis syndrome, considering the large mass and compromised renal function, a tumour lysis profile was requested, which revealed elevated serum calcium levels (15.4 mg/dL, which goes against the tumour lysis syndrome). Considering the large retroperitoneal lymph nodal mass, suppressed parathyroid hormone levels (4.1 pg/mL) and vitamin D3 being within normal range, a paraneoplastic cause of hypercalcaemia was considered. Correction of hypercalcaemia with medical measures as well as treatment of seminoma was instituted, which led to normalisation of renal function tests within the next 10 days. Here, the authors report a rare case of testicular seminoma with persistently deranged renal function, likely due to paraneoplastic hypercalcaemia, which improved after successful chemotherapy along with anti-hypercalcaemic measures, including aggressive hydration, diuretics, calcitonin, dexamethasone, and denosumab. This report shows that it is important to treat the cause along with medical management in this oncologic metabolic emergency. It also highlights the value of pre-phase chemotherapy with carboplatin and etoposide in the setting of acute renal impairment.