[Perirenal involvement in Waldenström disease]

To describe radiological, histological findings and cytometric features of perirenal masses: an unusual involvement pattern of the kidney by Waldenström disease. This pattern, not associated with nodal regional disease should be considered in the differential diagnosis of perirenal pathology (extramedullary hematopoiesis, liposarcoma, haematoma...).

A 68-year-old man, with Waldenström macroglobulinemia presented in ultrasound exploration bilateral perirenal hypoecogenic mass. Histopathological examination and cytometric determination of fine-needle aspiration biopsy showed a monoclonal lymphoplasmocitoid proliferation of B-cells arranged in a diffuse pattern.

Although perirenal involvement of the kidney by non Hodgkin lymphoplasmocitoid lymphoma is a rare phenomenon, this disease should be considered in differential diagnosis of perirenal pathology. Histological and cytometric examination are essential for diagnostic evaluation.