Clinical History
case1 weight loss and chest infection,known history of renal stones
case2 haemoptysis,ex smoker
Imaging Findings
CASE 1
Age: 39
Sex: female
Presentation and clinical findings:
The patient presented with weight loss, chest infection , night sweats, mild fever and productive cough of two weeks duration.
Medical history was uneventful apart from known left renal calculi for which she had lithotripsy several years earlier.
On examination she looked unwell and there was clinical evidence of left lung pneumonia.
She underwent bronchoscopy, which was normal.
Radiology :
An abdominal ultrasound (US) and computed tomography (CT) scans showed focal enlargement of the upper pole of the left kidney which contained several cystic areas with signs of perinephric involvement (fig1). Several left renal calculi were seen.
Extensive consolidation and moderate pleural effusion was noted in the left lung base (fig2).
A small calcified density was seen within the pleural fluid.
The diagnosis of renal abscess was made and pus was aspirated from the lesion under CT guidance. A Renogram showed a non-functioning left kidney.
Surgical findings:
The patient underwent exploratory surgery and nephrectomy of a grossly infected and adherent Lt.kidney.
Post operative progress:
A large tube drain was left behind in the renal bed and irrigation with sugar paste was commenced during the postoperative week.
On several occasions during the post operative week the patient complained of being able to taste the sugar soon after the irrigation procedure which the surgeon thought was amusing and inexplicable.
Prior to drainage- tube removal, contrast was injected into the tube to assess the size of the residual cavity. Unexpectedly the contarst opacified the Lt.bronchial tree indicating the presence of a nephro bronchial fisula. (fig.3)
Pathology:
Pathological examination showed calculus renal disease with evidence of XGP and multiple abscess formation.
CASE 2
Age: 66
Sex: female
Presentation and clinical findings
Several episodes of haemoptysis. A chest radiograph (fig.4)showed a 2.5cm opacity in the right lower zone adjacent to the Rt.hemidiaphragm.A small calcified density was seen within the lesion.
The patient was an ex-smoker of two years, having smoked from the age of 21 to 64.
There was no history of renal problems or complaints.
Clinical examination was unremarkable. The ESR was raised at 80mm/hr.
Radiology :
CT scan showed a mass at the base of the RT.lung which contained a single calcified focus at its center and surrounded by pleural inflammation with involvement of the Rt.hemidiaphragm and extention onto the Rt.renal area (fig.5).
The Rt. kidney was replaced by a large fatty mass causing displacement and mild compression of the Inferior vena cava.A sizeable central calcified focus was seen within the fatty lesion consistant with a staghorn calculus(Fig7). Small pockets of fliud density were also seen suggesting small abscesses (fig.6)
No recognizable functioning renal tissue was identified.
An abdominal radiograph confirmed the presence of a RT. Staghorn calculus (fig.7)
A diagnosis of XGP with trans diaphragmatic pulmonary fistula formation and massive replacement lipomatosis of the Rt. kidney was made based on the above findings.
Conservative management:
The patients was treated with antibiotics and discharged from the hospital with elective Rt nephrectomy scheduled in the coming few weeks.
She was readmited two weeks later with fever and backache.
A second CT scan demonstrated a large Rt.Ileo-psoas abscess connected to the Rt.renal bed (fig.8).The collection was drained percutaneously under CT guidance .
Proteus mirabilis was isolated and appropriate antibiotics started.
Surgical findings and post operative progress:
A Right nephrectomy was performed eight weeks later. The surgery was extremely difficult with significant blood loss. The fatty mass was adherent to the duodenum, venacava, right lobe of the liver, posterior abdominal wall and the diaphragm.
With careful dissection the bulk of the lesion was excised although it was not possible to resect the peri hepatic tract leading to the diaphragmatic undersurface.
The patient made uneventful recovery and was discharged home two weeks later.
Pathology:
Histology of the resected lesion showed very scanty residual renal tissue with marked fibrosis. There was marked inflammatory infiltrate focally xanthogranulomatous and with focal abscess formation.
The histological diagnosis was of chronic calculus XGP.
Discussion
DISCUSSION
XGP is a rare destructive inflammatory disease of the renal parenchyma usually caused by infection secondary to renal calculus disease.
Inflammatory reaction with lipid-laden macrophages (xanthoma cells) causes progressive destruction of the medulla and cortex and is most often unilateral.
Involvement of the Psoas muscle, Diaphragm, Duodenum, Small bowel, Colon and Lung with fistula formation has been described (1)
The pre-operative diagnosis of XGP is very difficult and occasionally the disease may mimic renal carcinoma.
CT is regarded as the imaging modality of choice in the diagnosis of XGP (2)
In our first patient it was retrospectively realized that the left perirenal collection was continuous with the left hemi diaphragm and was the cause for left lung infection via a nephro-bronchial fistula.
The small calcified opacity seen within the pleural fluid would be compatible with cross-diaphragmatic migration of a left renal calculus.
The diagnosis of XGP was suspected preoperatively in case 2 based on the CT findings of almost total renal atrophy, the presence of a large central staghorn calculus and small abscess /cavities and the demonstration of a nephro-pulmonary fistula
The calcified focus seen within the Rt. lung opacity seen on chest radiograph and CT was due to renal stone migration as in our first case. To our knowledge this finding has not been previously reported in the English literature.
The associated Extensive Replacement Lipomatosis is a very rare finding in XGP, although both have similar predisposing factors, the coexistence of these conditions has been reported in only one case (3).
Replacement lipomatosis is a condition of severe atrophy and destruction of the renal parenchyma with massive fat deposition, this condition is associated with long standing infection and with renal calculi in79% of cases (5), significant mass effect was seen in our case a finding which may be confused with fat containing tumors such as liposarcoma (4)
Nephro-pulmonary fistula and lung abscesses are extremely rare complications of XGP and only few cases has been reported in the literature, on the other hand other types of renal infection can cause nephro –pulmonary fistulas, since 1900, 24 cases of nephro-pulmonary fistulas associated with perinephric abscess have been repoterd.(5)
In conclusion
Although XGP is primarily a renal disease it can present in many different ways.
Both our cases presented with pulmonary complaints (chest infection and left basal consolidation in the first case, cough, haemoptysis and lung mass in the second case).
Our two cases emphasize the need to consider renal abnormality as a predisposing factor for lung abscess and empyema even in the absence of abdominal pain or urinary symptoms
Differential Diagnosis List
Renal XGP with nephro-pulmonay fistula and chest infection and massive replacement lipomatosis(case2)
Final Diagnosis
Renal XGP with nephro-pulmonay fistula and chest infection and massive replacement lipomatosis(case2)
