==inizio abstract==

A63 years old male patients presented with hyperpyrexia from two weeks, treated by the general practitioner with dual antibiotic combination treatment.Personal history was negative for neoplasm, urinary stone or other significant urologic disease.His physical examination was unremarkable, except for a mild knocking pain at the right flank.Blood tests revealed only a neutrophilic leukocytosis. Chest X-ray was negative.
Abdominal Ultrasonography(US)revealed a voluminous perirenal multiloculated mass with thickened wall with a few solid areas.
The Computed Tomography(CT)showed a 10x7x6 cm polilobated mass with a prevalent cystic component with intermediate density, at the lower pole, as in a complicated infected cyst or a perirenal abscess.
We pose the diagnosis of urosepsis by presumed renal abscess.
After several attempts of reclaim with antibiotic therapy and subsequent percutaneous drainage, the patient was submitted to excision of the abscess,preserving the normal renal parenchyma.
The examination of the specimen showed a well demarked,excavated necrotic-hemorrhagic lesion, microscopically constituted of reactive logistic cells,resembling a xantogranulomatous inflammatory process,with adjacent well differentiated fatty tissue.In both the components there were scattered atypical stromal elements with atypical hypercromatic nuclei,with occasionally mitotically active, immunoreactive for MDM2 and CD4.Because of the challenging diagnosis the histological slides were rewied by a dedicated patologist, that confirm a dedifferentiated liposarcoma(DDLPS),extended to the excision margins.
DDLPS account approximately 10% of all liposarcoma, the metastatic rate account about 15-20% of the cases irrespective of histologic grade.These lesions often pose greater problems in terms of local control, particular to this difficult anatomic location.Mortality is more often related to uncontrolled local recurrence, and time to relapse to the extension of the surgical resection.
Due to the inefficiency of adjuvant therapy, surgery remains the only effective treatment.The gold standard should be to achieve a complete resection with clean surgical margins.
At 6 months follow up the patient has no disease recurrence or metastases.

==fine abstract==