Emphysematous pyelonephritis presenting as necrotizing fasciitis of the leg.

Abstract

We report a 50-year-old man with poorly controlled diabetes mellitus who presented with a painful, swollen right leg. He had also experienced right flank pain for 1 week prior to admission. Physical examination was notable for tenderness over the right flank. The right leg was diffusely swollen and exquisitely tender to touch, with palpable crepitance. Laboratory tests revealed leukocytosis and pyuria. Computed tomography showed a right ureteral stone with hydronephrosis and characteristic findings of emphysematous pyelonephritis. Furthermore, a right perirenal gas-forming abscess with extension to the right leg was noted. The patient was successfully treated with antibiotic therapy, aggressive control of blood sugar, percutaneous drainage of the hydronephrosis and perirenal abscess, and aggressive debridement of the leg.

Full text

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Introduction
Emphysematous pyelonephritis is an uncommon and
life-threatening infection of the kidney. The disease
usually occurs in patients with diabetes mellitus, with
or without obstructive uropathy, and is characterized
by gas accumulation in the renal parenchyma, collect-
ing system, or perirenal tissue. Clinical symptoms and
signs are often similar to those of uncomplicated pyelo-
nephritis. Delay in diagnosis is usually due to nonspe-
cific manifestations, such as fever, flank pain, nausea,
and vomiting, and results in high mortality rates. We
report an unusual case of emphysematous pyelonephri-
tis presenting as necrotizing fasciitis of the ipsilateral
leg. Based on thorough history-taking and detailed
physical examination, accompanied by essential imag-
ing studies, we were able to establish an early diagnosis
and plan appropriate management, which resulted in
a good outcome.
Case Report
A 50-year-old man with diabetes mellitus presented
to the emergency department with a painful, swollen
right leg. The pain and swelling began 3 days before
presentation, worsening until he was unable to walk.
Furthermore, he had experienced right flank pain for
1 week before the beginning of the right leg pain. On
physical examination, his body temperature was 38.5°C
and he had tenderness over the right flank. The right
leg was diffusely swollen and exquisitely tender to
touch, with palpable crepitance.
Complete blood count on admission showed a
white blood cell count of 19,200/μL, hemoglobin of
12.4g/dL, and platelet count of 250,000/μL. Blood
chemistries showed urea nitrogen 19.1mg/dL, crea-
tinine 1.1mg/dL, glucose 418mg/dL, and HbA1c
15.3%. Urinalysis was remarkable for 3+ occult blood,
with numerous white blood cells per high-power field
in the urinary sediments.
Computed tomography showed a right ureteral
stone with hydronephrosis and gas bubbles in the renal
parenchyma and collecting system (Figure 1). A gas-
forming abscess below the right kidney was also noted.
The presence of gas in the right lateral abdominal wall
suggested necrotizing fasciitis and an extension of the
inflammatory process from the retroperitoneal abscess.
Moreover, the necrotizing fasciitis further extended
to the right leg (Figure 2).
J Chin Med Assoc • March 2009 • Vol 72 • No 3
© 2009 Elsevier. All rights reserved.
160
CASE REPORT
Emphysematous Pyelonephritis Presenting as
Necrotizing Fasciitis of the Leg
Yu-Xiong Ye, Yao-Ko Wen*
Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan, R.O.C.
We report a 50-year-old man with poorly controlled diabetes mellitus who presented with a painful, swollen right leg. He had
also experienced right flank pain for 1 week prior to admission. Physical examination was notable for tenderness over
the right flank. The right leg was diffusely swollen and exquisitely tender to touch, with palpable crepitance. Laboratory
tests revealed leukocytosis and pyuria. Computed tomography showed a right ureteral stone with hydronephrosis and
characteristic findings of emphysematous pyelonephritis. Furthermore, a right perirenal gas-forming abscess with extension
to the right leg was noted. The patient was successfully treated with antibiotic therapy, aggressive control of blood sugar,
percutaneous drainage of the hydronephrosis and perirenal abscess, and aggressive debridement of the leg. [J Chin Med
Assoc 2009;72(3):160–162]
Key Words: emphysematous pyelonephritis, necrotizing fasciitis
*Correspondence to: Dr Yao-Ko Wen, Division of Nephrology, Department of Medicine, Changhua Christian
Hospital, 135, Nanhsiao Street, Changhua 500, Taiwan, R.O.C.
E-mail: 45440@cch.org.tw
● Received: May 28, 2008
● Accepted: October 17, 2008

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The patient was treated with antibiotic therapy,
aggressive control of blood sugar, percutaneous drain-
age of the right hydronephrosis and perirenal abscess,
and aggressive debridement of the right leg. Urine
culture grew Escherichia coli. Culture of the perirenal
abscess grew Escherichia coli and Klebsiella oxytoca.
The result of the blood culture was negative.
Over the next 2 weeks, the patient underwent
debridement of the affected right leg twice, and per-
cutaneous nephrolithotomy was performed 1 month
after admission. The patient was discharged with the
right leg fully recovered.
Discussion
Emphysematous pyelonephritis is a gas-producing,
necrotizing infection involving the renal parenchyma,
collecting system, or perirenal tissue. The mechanism
of gas formation is still unclear. Most cases occur in
uncontrolled diabetes mellitus. Other risk factors in-
clude urinary tract obstruction and urinary tract infec-
tion with gas-forming microorganisms.1Two types
of disease are recognized: type I is characterized by
extensive destruction of renal parenchyma with the
presence of mottled gas, and type II is characterized
by renal or perirenal fluid collection with loculated gas
or gas in the collecting system.2Type I emphysema-
tous pyelonephritis has a more fulminant course and
frequently requires surgical nephrectomy. For local-
ized emphysematous pyelonephritis, the success rate
of antibiotic treatment, with or without percutaneous
drainage, has improved substantially in recent years.3,4
In general, the mortality rate is higher in type I than
type II patients (69% vs. 18%).5In this case, the com-
puted tomography findings were compatible with the
description of type II emphysematous pyelonephritis.
Necrotizing fasciitis is a deep-seated infection of
subcutaneous tissue that is characterized by progressive
necrosis of the fascia and fat.6Diabetes mellitus is also
the most common predisposing factor. The disease has
a fulminant course and is associated with considerable
mortality. There may be a remarkably rapid progression
from an inapparent process to one associated with
extensive destruction of subcutaneous tissues and signs
of systemic toxicity. Early recognition and treatment
by a combination of surgical debridement, appropriate
antibiotics and optimal oxygenation of the infected
tissues are mandatory.7
Both emphysematous pyelonephritis and necrotiz-
ing fasciitis are life-threatening conditions and require
prompt aggressive medical and surgical intervention.
The combined occurrence of the 2 entities is extremely
unusual. Although necrotizing fasciitis can be caused by
a retroperitoneal infection, only 2 cases of necrotizing
fasciitis associated with emphysematous pyelonephritis
have been described previously in the literature.8–10
A pathophysiology of emphysematous pyelonephritis
extending to the adjacent subcutaneous tissues has been
proposed.9The superior and inferior lumbar triangles
are 2 sites of anatomic weakness in the abdominal wall
of the flank due to the absence of external muscular
layers. The classic sign of subcutaneous discoloration
J Chin Med Assoc • March 2009 • Vol 72 • No 3
161
Emphysematous pyelonephritis combined with necrotizing fasciitis
Figure 1. Computed tomography shows right hydronephrosis, gas
bubbles in the renal parenchyma and collecting system (black
arrow), and perirenal gas-forming abscess (white arrow).
Figure 2. Computed tomography, coronal view, clearly demon-
strates a right ureteral stone with hydronephrosis (black arrow)
and a gas-forming abscess below the right kidney, with extension
to the right leg (white arrow).

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in the flank (Grey Turner sign) associated with acute
pancreatitis and traumatic lumbar hernia are known
to develop through these triangles.11The inferior lum-
bar triangle pathway also provides an anatomic expla-
nation for the development of necrotizing fasciitis from
the retroperitoneal infection.
In conclusion, we have presented a case of emphy-
sematous pyelonephritis complicated with necrotizing
fasciitis. Computed tomography showed characteristic
findings of emphysematous pyelonephritis and perire-
nal gas-forming abscess with extension to the ipsilateral
leg. This case not only represents a concurrence of the
2 uncommon entities but also alerts us that necrotiz-
ing fasciitis may be the presenting feature of emphyse-
matous pyelonephritis. In cases of necrotizing fasciitis
of the leg with no obvious source, a retroperitoneal
nidus of infection may be considered.
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