A case of myospherulosis occurring in the perirenal adipose tissue

The authors report a case of spontaneous myospherulosis that developed in the right perirenal adipose tissue, presented like an abcess, in an 82-year-old man of the A, Rh + blood group. The patient had a history of chronic lymphocytic leukaemia. Fine needle aspiration and histological examination of the renal cyst allowed the observation of 4- to 7-μm spherules (or endobodies) enclosed in saccular structures (or parent bodies) and accompanied by a foreign body-type response. The walls of the parent bodies were negative for PAS, Gomori's methenamine silver and Giemsa's stain. Immunohistochemical study was positive with anti A antibody specific of A1/A2 blood group and with anti glycophorin A antibody. The authors reviewed the literature concerning this rare lesion: it usually occurs in subcutaneous fat or in the paranasal sinuses, nose and middle ear but, up to now, no previous case has ever been reported in the urinary tract. The only case of visceral myospherulosis previously reported occurred in a cystic teratoma of the ovary. The reported case is also peculiar by the unusual thickness of the parent bodies. The authors also discuss the mechanism of the disease and suggest that, in the present observation, myospherulosis could have been induced by the rupture of a preexisting cyst in the perirenal adipose tissue.