[Membranous glomerulonephritis as a paraneoplastic manifestation of melanoma]

Membranous glomerulonephritis (MG) is generally idiopathic. Causes of secondary MG (15 % of cases), namely solid or haematological cancers, are common, with parallel development between the two diseases suggesting paraneoplastic syndrome. However, paraneoplastic syndrome is rare in melanoma. We report a case of a patient with stage III melanoma presenting MG developing in parallel to the melanoma.

A 61-year-old man was referred for melanoma on the right side with a Breslow index of 3mm, and without ulceration. While the patient had no adenopathy, he was presenting severe hypertension diagnosed two months earlier as well as diffuse pitting oedema, with weight gain of 15kg in one month. Additional treatment of the patient's melanoma included extended excision, examination of the two right axillary sentinel nodes (positive), and axillary lymph node dissection revealing four more metastatic nodes. A thoracic-abdominal-pelvic CAT scan showed no further metastasis. Investigation of the oedema revealed nephrotic syndrome with hypoalbuminaemia of 14g/L and proteinuria of 5g/24h. Renal biopsy resulted in the diagnosis of MG. Histological and immunohistochemical examination (HMB-45, Melan A, S100 protein) showed no tumour cells in the kidney, and urinary cytology was negative. Non-tumoral causes of MG were thus ruled out. The oedema regressed rapidly following surgical treatment of the melanoma, with no specific renal or oncological treatment being given. Two years after axillary lymph node dissection, the patient was in complete remission of his melanoma and renal tests showed spontaneous regression of nephrotic syndrome, with disappearance of the oedema, normalisation of blood pressure and gradual correction of serum albumin (40g/L) and proteinuria (1g/24h).

Paraneoplastic MG has been described particularly in patients with gastrointestinal and pulmonary cancer. To our knowledge, this is only the second case associated with melanoma. Our report suggests the need for routine cutaneous examination as part of the initial investigations for MG.