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Post-radiotherapy osteomyelitis of the symphysis pubis: Computed tomographic features
Clinical Radiology (1998) 53, 126-130
Post-radiotherapy Osteomyelitis of the Symphysis Pubis: Computed Tomographic Features T. A. WIGNALL, B. M. CARRINGTON and J. P. LOGUE
Department of Diagnostic Radiology, Christie Hospital NHS Trust, Withington, Manchester, UK We report the clinical and computed tomography (CT) features of seven patients with osteomyelitis of the symphysis pubis following radiotherapy for bladder (n = 4) or cervical (n = 3) carcinoma. The patients presented with fistulae (n = 5), pain (n = 1) or small bowel obstruction (n = 1) between 6 and 19 years after radiotherapy. The diagnosis was confirmed by surgery with histology or bacteriology of the symphysis pubis and/or associated abscess in all patients. In addition to bone destruction, other features identified on CT included abscesses, bowel loops adherent to the symphysis pubis and/or communicating with an abscess cavity, a soft tissue mass enveloping the residual bone, and fistulae. The combination of clinical and radiological features suggests osteomyelitis and, for patients who have had pelvic radiotherapy, this treatable condition should be included in the differential diagnosis of solitary symphysis pubis destruction. Wignall, T.A., Carrington, B.M. & Logue, J.P. (1998). Clinical Radiology 53, 126-130. Post-radiotherapy Osteomyelitis of the Symphysis Pubis: Computed Tomographic Features
Accepted for Publication 11 June 1997
Osteomyelitis of the symphysis pubis is a recognized complication of genitourinary or gynaecological surgery, with infection usually occurring between 2 weeks and 2 months after surgery [1]. Other causes include trauma and pregnancy [2] but the condition may also be idiopathic [3]. A review of the English language literature has revealed one case of osteomyelitis following radiotherapy in a patient with carcinoma of the prostate who developed a recto-urethral fistula 5 years post-radiotherapy [4] and there is one Russian article in which five patients out of 53 treated with radiation for uterine cancer developed osteomyelitis [5]. We present seven patients who developed osteomyelitis of the symphysis pubis several years after radiotherapy. We illustrate the clinical and radiological features which may suggest a diagnosis of radiation-associated osteomyelitis and which may help to distinguish osteomyelitis from tumour recurrence or simple radionecrosis.
PATIENTS AND M E T H O D S The clinical and radiological records of seven patients (three male and four female, age range 46-72 years) who developed osteomyelitis of the symphysis pubis and underwent computed tomography (CT) were reviewed. The patients had been treated with radiotherapy; four for bladder cancer and three for cervical cancer. All of the patients underwent surgery after radiotherapy, three for tumour recurrence and radiation complications, and four for radiation complications alone. Each patient had between one and three laparotomies but no patient had surgery less than 1 year before the onset of osteomyelitis and, of the three patients operated on for recurrence, two had been tumour free for 9 and l 1 years, respectively, before developing osteomyelitis. Correspondence to: Dr B. M. Carrington, Department of Diagnostic Radiology, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester M20 4BX, UK. 9 1998 The Royal College of Radiologists.
The patients presented because of fistulae (n = 5), pain (n = 1) or small bowel obstruction (n = 1) between 6 and 19 years after radiation therapy. CT was performed on an IGE Pace scanner with 10mm sections at 10mm intervals through the abdomen and pelvis. Oral contrast (900 ml Gastrografin 3%, Schering) was administered over the course of 1 h prior to the scan and all patients received intravenous contrast (200ml of Omnipaque 240 (Schering) by drip infusion in the antecubital fossa). Two patients went on to have CT sinograms using 10ml of Onmipaque 200. Six patients underwent laparotomy with bacteriological and/or histological confirmation from either the pubis, the abscess cavity directly adjacent to the area of bone destruction or the immediately adjacent soft tissues. One patient died from sepsis and a post-mortem was performed.
RESULTS The clinical and radiotherapy details of patients are recorded in Table 1. All patients received radical radiotherapy administered in a standard fashion and one patient (case 1) had a repeat external beam treatment for localized tumour recurrence. The mean time between radiation therapy and development of osteomyelitis was 13.9 years (range 6 - 2 0 years). In the intervening period, all the patients had surgery to the bladder for either recurrent tumour (n = 3) or pelvic radiation disease (n = 4) and six patients had bowel surgery, all for radiation change. However, no patient had surgery less than 12 months before the development of osteomyelitis. The relevant CT features are recorded in Table 2. All patients showed destruction of the symphysis pubis. The nature of this destruction was typically that of fragmentation with patchy lytic and sclerotic areas (Figs 1 and 2). Only one patient (case 1) showed a clear periosteal reaction and, subsequently, a fracture (Fig. 3). Neither sequestra nor cloacae were identified on CT. No other bone lesion was
127
OSTEOMYELITIS OF THE SYMPHYSIS PUBIS Table 1 - Clinical information
and treatment
d e t a i l s p r i o r to o s t e o m y e l i t i s
Patient Age~sex Primary Tumour Radiotherapy dose tumour stage (cGy)/fractions E-B*
1
37/F
Cervix
2B
(1) 3990/15 (2) 3500/8
Interval (years)
Surgical resections after treatment of primary tumour
1- C'~
900 (point A)
Radiotherapy to Most recent osteomyelitis surgery to osteomyelitis
Procedure (years after primary treatment)
Radiation change Tumour
1 Rectosigmoid (2) 2 Bladder (3) 3 Small bowel (8)
+ + +
-
9
1
2
45/F
Bladder 4
5500/16
+
-
10
3.5
3
59/M
Bladder 2
5500/16
1 Bladder (8) 2 Rectosigmoid (12)
+ +
-
13
1.5
4
57/M
Bladder
1
5500/16
1 Bladder (1) 2 Small bowel (10)
+
+ 10
9
5
58/F
Cervix
3A
1 Pelvic clearance (5) 2 Small bowel (5)
+ +
+
6
1
6
55/M
Bladder 2
5500/16
1 Bladder (2) 2 Small bowel (14)
+ +
+
13
12
7
33/F
Cervix
5000/16
1 Large bowel (6) 2 Bladder (7)
+ +
-
19
13 I
3B
Bladder (10)
Histology
6700 (point A)
4000 (surface dose)
-
* External beam, t intracavitary.
Fig. 1 - Patient 7. CT scan (bone windows) showing extensive fragmentation of the symphysis pubis and a small air pocket (anow) in the symphysis.
identified on bone window interrogation of the thoracoabdominopelvic CT scans of each patient. One patient had a bone scan which showed the symphysis pubis lesion to be solitary. Abscess cavities with or without air/fluid levels were present in six patients on CT (Figs 2 - 4 ) and in one at Table 2 - Key computed
Patient
tomographic
Fig. 2 - Patient 5. CT scan (bone windows) showing sclerosis and fragmentation of the symphysis pubis (arrow). Note the abscess cavity (asterisk) and thickened fight obturator internus muscle (O).
surgery prior to CT. The abscesses were directly adjacent to the area of bone destruction and, in five patients, small bowel was adherent to the abscess collection. Inflammatory soft tissue masses featured in five patients,
features
Solitary destruction of symphysis pubis
Soft tissue mass
1
+
+
2 3 4 5 6 7
+ + + + + +
+ + + +
Sinus~fistula
Abscess
Bowel associated with abscess
-
+
+
+ + + +
+ + -* + + +
+ -* + + +
* Emergency surgery had 1o be performed immediately prior to CT in this patient when an abscess was found to be involving the symphysis pubis with adherent loops of small bowel, one of which had perforated. 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
128
CLINICAL RADIOLOGY
Fig. 3 - Patient 1. CT scan (bone windows) showing sclerosis of the superior right pubic ramus with a fracture (straight arrow). Note the pelvic abscess (asterisk) and intimately related small bowel (curved arrow). (See Fig. 4a for lower section on this patient.)
Fig. 5 - Patient 4. CT scan (soft tissue settings) showing extensive soft tissue mass (m) around the symphysis pubis and symmetrical thickening of the anterior portions of the obturator internus muscles (white arrows).
which were symmetrical around the bone changes, but often extended to involve adjacent muscle groups particularly the obturator internus and the rectus abdominis muscles, leading to a uniform thickening of these muscles (Fig. 5). Although five patients had clinical evidence of a fistula, this was identified on CT in only four: two patients had CT sinograms (Fig. 6), one patient showed an enteric communication with the abscess and the fourth had a rectovaginal
(a)
(a)
(b) Fig. 4 - (a) Patient 1. CT scan on soft tissue settings showing abscess cavity (black asterisk) behind the symphysis pubis and extending into the right obturator foramen. Despite the soft tissue windows fragmentation of the symphysis can be seen. A surgical clip is also present in the pelvis. (b) Patient 4. CT scan on soft tissue settings demonstrating an abnormal gas collection (white asterisk) extending into the fragmented symphysis pubis
(arrow).
(b) Fig. 6 - (a, b) Patient 3. CT sinogram on bone settings showing contrast in the sinus (arrow) on the anterior abdominal wall extending towards loops of small bowel (a). At a lower level (b) contrast extends into the symphysis pubis and into the true pelvis (arrows). 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
129
OSTEOMYELITIS OF THE SYMPHYSIS PUBIS
Table 3 - Clinical and laboratory data at time of osteomyeliti s Patient
Surgical findings
Bacteriology~histology Organism and site of isolation
Treatment
1
Pelvic abscess extending to symphysis pubis with vaginal fistula
Bacteroides and Enterococci (from peripubic abscess)
Fistula repair Abscess debridement Maintenance antibiotics
2
Abscess extending into pectineus muscle and symphysis pubis
Bone biopsy confirmed (right and left pubic rami)
Abscess drainage and curettage
3
Fistula from colon to thigh via pubic abscess
Bacteroides and Diphtheroids (from peripubic abscess)
Multiple abscess debridements
4
Small bowel perforation into pelvic abscess which communicated with symphysis pubis
Staph. aureus (from peripubic abscess)
Abscess drainage Small bowel resection
5
Abscess extending to symphysis pubis with vaginal fistula
Enterococci and Pseudomonas (from peripubic abscess)
Fistula repair Abscess debridement
6
Fistula to abdominal wall and left thigh with small bowel perforation and pelvic abscess involving symphysis pubis
Coliforms and group B Streptococci (from peripubic abscess)
Abscess debridement Small bowel resection
7
Recto-vagino abscess extending to symphysis pubis
Enterococci (from peripubic abscess)
Abscess drainages
fistula, which was demonstrable on CT with an adjacent abscess and adherent obstructed small bowel. The organisms isolated, histological results and treatment each patient received are recorded in Table 3. In six out of seven patients, the bacteria isolated were bowel organisms. Follow-up On follow-up (Table 4) two patients were well after treatment for their osteomyelitis. One patient had a recurrent abscess and septic arthritis of the left hip and is now on longterm antibiotics. One patient had further severe pelvic sepsis with multiple fistulae but has now completely recovered. This patient has had several laparotomies and the histology and bacteriology have shown only infection and radiation change with no evidence of tumottr. Three patients had died; at post-mortem one had pelvic sepsis, including symphysis pubis osteomyelitis, and there was small bowel obstruction with no evidence of tumour. One died from a myocardial infarction 2 years after treatment for osteomyelitis, at which time a post-mortem showed no tumour or pelvic sepsis. The third patient died of carcinomatosis after 12 months. DISCUSSION In patients who have received radiotherapy for cancer, the differentia/ diagnosis of a bone lesion typically rests
between a metastasis and radionecrosis. In our experience, osteomyelitis must be added to that differential in patients who have sustained symptomatic radiation effects, and this is important because effective treatment is available using a combination of surgical debridement and long-term antibiotics. Accepted diagnostic criteria for osteomye!itis include two out of three of the following: radiological changes, typical histological features or positive microbiological cultures [6,7]. Using these criteria, all of our patients can be diagnosed as having osteomyelitis. There are several clinical and radiological features common to our patient cohort. All had sustained severe pelvic radiation change that necessitated surgical intervention. There was a long time interval between the original radiotherapy and the onset of osteomyelitis and over 1 year between prior pelvic surgery and the onset of sepsis. The coexistence of lytic and sclerotic bone change symmetrically involving the pubic bones, directly associated with a pelvic abscess and, in some cases, with gas within the symphysis pubis or intestinal fistulae, were features suggestive of infection. Metastatic bone involvement was unlikely in our patients for several reasons. The lesion was solitary as indicated by normal CT bone window interrogation in all patients and a normal radionuclide bone scan in one patient. The destruction was symmetrical, affecting the bone on both sides of the joint space which would be most unusual for a solitary
Table 4 - Follow-up Patient
Post-osteomyelitis length of follow-up
Alive and well
Further pelvic sepsis
Dead
Post-mortem
+ +
Myocardial infarction. No tumour
+
Abdominopelvic sepsis including symphysis pubis osteomyelitis. No tumour
(years) 1
5
2 3 4 5 6
4 5 2 1 5
+ Including septic arthritis of left hip + +
+
Including multiple perineal fistulae without tumour at surgery 7
0.1
9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
130
CLINICAL RADIOLOGY
metastasis. In addition, a minimum of 6 years had elapsed between treatment of the primary tumour and the development of the bone lesion that considerably reduces the likelihood of metastatic disease [8], which will occur within 5 years in 88% of patients with cervical cancer [9] and in 95% of patients with bladder cancer [10]. Cervical cancer bone metastases are almost invariably lyric [11] and bladder cancer bone metastases are usually lyric [12]. Therefore, the mixed lytic/sclerotic nature of the bone lesions in our patients would also mitigate against metastases. Following the introduction of mega-voltage radiotherapy, there has been a reduction in the absorbed bone dose helped by better collimated fields and changes in therapy regimens. This has resulted in a significant decrease in radionecrosis, although inevitably the bone will sustain minor radiation effects. Radionecrosis may result in osteopenia alone, or patchy osteopenia with sclerosis and there is an increased risk of fractures in radiation-affected bone. The changes are confined to the irradiated area and therefore may cross joint boundaries to affect multiple bones. There is little doubt that our patients do have some degree of radiation-induced bone changes but pure radionecrosis is not associated with a soft tissue mass or abscess formation [11] and the presence of soft tissue masses, fistulae and abscesses in our patients indicates that the dominant pathology is one of infection. The clinical and bacteriological features (particularly the intestinal origin of the infecting organisms in six out of seven patients) would suggest that the osteomyelitis results from visceral radiation damage causing local pelvic sepsis and direct spread to radiation-affected bone. Indeed, two patients had a pelvic small bowel perforation contributing to the local sepsis with histological evidence of radiation therapy effect in the resected bowel. Six out of seven patients responded to conventional treatment for osteomyelitis thereby providing additional support for the diagnosis. One patient was thought to have recurrent pelvic tumour by virtue of the symphysis pubis abnormality and managed accordingly. This patient developed small bowel obstruction and was then referred for clinical and radiological review. Unfortunately, the patient died and post-mortem demonstrated abdominal sepsis with
multiple abdomino-pelvic abscesses, and symphysis pubis osteomyelitis, but no evidence of tumour recurrence. These patients illustrate the need to consider an infective aetiology for solitary destruction of the symphysis pubis in combination with a soft tissue mass, abscess or fistula in patients who have had radical pelvic radiotherapy and are on long-term follow-up. Acknowledgements. We would like to thank Mr N.W. Clarke and Mr R. J. Barnard for permission to report these cases. We would also like to thank Mrs Kami Ramnarain for assisting in the preparation of the manuscript and the Department of Medical Illustration for photographic assistance. REFERENCES 1 Rosenthal RE, Spickard WA, Markham RD et al. Osteomyelitis of the symphysis pubis: a separate disease from osteitis pubis. Journal of Bone and Joint Surgery (Am) 1992;64:123-128. 2 Rowarth G. Osteomyelitis of the pubic bones and staphylococcal septicaemia complicating pregnancy. Journal of Obstetrics and Gynaecology (British Empire) 1940;47:213-216. 3 Lindeque BG, Mennen U. Infectious osteitis pubis. South African Medical Journal 1985;67:689-691. 4 Thompson IM, Marx AC. Conservative therapy of rectourethral fistula: five year follow up. Urology 1990;35:533-536. 5 Gun'ko RI, Krasnov AS. Radiation injuries of the bones during treatment of uterine cancer. Voprosy Onkologii (Leningrad) 1988; 34:1188-1195. 6 Waldvogel FA, Medoff G, Swartz MN. Osteomyelitis: a review of clinical features, therapuetic considerations and unusual aspects (first of three parts). New England Journal of Medicine 1970;282:198. 7 Burns JR, Gregory JG. Osteomyelitis of pubic symphysis after urologic surgery. Journal of Urology 1977;118:803-805. 8 Liebshitz HI. Radiation changes in bone. Seminars in Roentgenology 1994;29:15 -37. 9 Fagundes H, Perez CA, Grigsby PW et al. Distant metastases after irradiation alone in carcinoma of the uterine cervix. International Journal of Radiation, Oncology, Biology and Physics 1992;24:197 - 204. 10 Duncan W, Quilty PM. The results of a series of 963 patients with transitional cell carcinoma of the urinary bladder primarily treated by radical megavoltage x-ray therapy. Radiotherapy and Oncology 1986;7:299-310. 11 Yousem DM, Magid D, Scott W W et al. Treated invasive cervical carcinoma - - utility of CT in destinguishing between skeletal metastases and radiation necrosis. Clinical Imaging 1989;13:147-153. 12 Malawer MM, Delaney TF. Treatment of metastatic cancer to bone. In: deVita VT, Hellman S, Rosenberg SA, eds. Cancer." principles and practice ofoncology. Philadelphia: JB Lippincott, 1989:2298-2316.
9 1998 The Royal College of Radiologists, ClinicalRadiology, 53, 126-130.
Post-radiotherapy Osteomyelitis of the Symphysis Pubis: Computed Tomographic Features T. A. WIGNALL, B. M. CARRINGTON and J. P. LOGUE
Department of Diagnostic Radiology, Christie Hospital NHS Trust, Withington, Manchester, UK We report the clinical and computed tomography (CT) features of seven patients with osteomyelitis of the symphysis pubis following radiotherapy for bladder (n = 4) or cervical (n = 3) carcinoma. The patients presented with fistulae (n = 5), pain (n = 1) or small bowel obstruction (n = 1) between 6 and 19 years after radiotherapy. The diagnosis was confirmed by surgery with histology or bacteriology of the symphysis pubis and/or associated abscess in all patients. In addition to bone destruction, other features identified on CT included abscesses, bowel loops adherent to the symphysis pubis and/or communicating with an abscess cavity, a soft tissue mass enveloping the residual bone, and fistulae. The combination of clinical and radiological features suggests osteomyelitis and, for patients who have had pelvic radiotherapy, this treatable condition should be included in the differential diagnosis of solitary symphysis pubis destruction. Wignall, T.A., Carrington, B.M. & Logue, J.P. (1998). Clinical Radiology 53, 126-130. Post-radiotherapy Osteomyelitis of the Symphysis Pubis: Computed Tomographic Features
Accepted for Publication 11 June 1997
Osteomyelitis of the symphysis pubis is a recognized complication of genitourinary or gynaecological surgery, with infection usually occurring between 2 weeks and 2 months after surgery [1]. Other causes include trauma and pregnancy [2] but the condition may also be idiopathic [3]. A review of the English language literature has revealed one case of osteomyelitis following radiotherapy in a patient with carcinoma of the prostate who developed a recto-urethral fistula 5 years post-radiotherapy [4] and there is one Russian article in which five patients out of 53 treated with radiation for uterine cancer developed osteomyelitis [5]. We present seven patients who developed osteomyelitis of the symphysis pubis several years after radiotherapy. We illustrate the clinical and radiological features which may suggest a diagnosis of radiation-associated osteomyelitis and which may help to distinguish osteomyelitis from tumour recurrence or simple radionecrosis.
PATIENTS AND M E T H O D S The clinical and radiological records of seven patients (three male and four female, age range 46-72 years) who developed osteomyelitis of the symphysis pubis and underwent computed tomography (CT) were reviewed. The patients had been treated with radiotherapy; four for bladder cancer and three for cervical cancer. All of the patients underwent surgery after radiotherapy, three for tumour recurrence and radiation complications, and four for radiation complications alone. Each patient had between one and three laparotomies but no patient had surgery less than 1 year before the onset of osteomyelitis and, of the three patients operated on for recurrence, two had been tumour free for 9 and l 1 years, respectively, before developing osteomyelitis. Correspondence to: Dr B. M. Carrington, Department of Diagnostic Radiology, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester M20 4BX, UK. 9 1998 The Royal College of Radiologists.
The patients presented because of fistulae (n = 5), pain (n = 1) or small bowel obstruction (n = 1) between 6 and 19 years after radiation therapy. CT was performed on an IGE Pace scanner with 10mm sections at 10mm intervals through the abdomen and pelvis. Oral contrast (900 ml Gastrografin 3%, Schering) was administered over the course of 1 h prior to the scan and all patients received intravenous contrast (200ml of Omnipaque 240 (Schering) by drip infusion in the antecubital fossa). Two patients went on to have CT sinograms using 10ml of Onmipaque 200. Six patients underwent laparotomy with bacteriological and/or histological confirmation from either the pubis, the abscess cavity directly adjacent to the area of bone destruction or the immediately adjacent soft tissues. One patient died from sepsis and a post-mortem was performed.
RESULTS The clinical and radiotherapy details of patients are recorded in Table 1. All patients received radical radiotherapy administered in a standard fashion and one patient (case 1) had a repeat external beam treatment for localized tumour recurrence. The mean time between radiation therapy and development of osteomyelitis was 13.9 years (range 6 - 2 0 years). In the intervening period, all the patients had surgery to the bladder for either recurrent tumour (n = 3) or pelvic radiation disease (n = 4) and six patients had bowel surgery, all for radiation change. However, no patient had surgery less than 12 months before the development of osteomyelitis. The relevant CT features are recorded in Table 2. All patients showed destruction of the symphysis pubis. The nature of this destruction was typically that of fragmentation with patchy lytic and sclerotic areas (Figs 1 and 2). Only one patient (case 1) showed a clear periosteal reaction and, subsequently, a fracture (Fig. 3). Neither sequestra nor cloacae were identified on CT. No other bone lesion was
127
OSTEOMYELITIS OF THE SYMPHYSIS PUBIS Table 1 - Clinical information
and treatment
d e t a i l s p r i o r to o s t e o m y e l i t i s
Patient Age~sex Primary Tumour Radiotherapy dose tumour stage (cGy)/fractions E-B*
1
37/F
Cervix
2B
(1) 3990/15 (2) 3500/8
Interval (years)
Surgical resections after treatment of primary tumour
1- C'~
900 (point A)
Radiotherapy to Most recent osteomyelitis surgery to osteomyelitis
Procedure (years after primary treatment)
Radiation change Tumour
1 Rectosigmoid (2) 2 Bladder (3) 3 Small bowel (8)
+ + +
-
9
1
2
45/F
Bladder 4
5500/16
+
-
10
3.5
3
59/M
Bladder 2
5500/16
1 Bladder (8) 2 Rectosigmoid (12)
+ +
-
13
1.5
4
57/M
Bladder
1
5500/16
1 Bladder (1) 2 Small bowel (10)
+
+ 10
9
5
58/F
Cervix
3A
1 Pelvic clearance (5) 2 Small bowel (5)
+ +
+
6
1
6
55/M
Bladder 2
5500/16
1 Bladder (2) 2 Small bowel (14)
+ +
+
13
12
7
33/F
Cervix
5000/16
1 Large bowel (6) 2 Bladder (7)
+ +
-
19
13 I
3B
Bladder (10)
Histology
6700 (point A)
4000 (surface dose)
-
* External beam, t intracavitary.
Fig. 1 - Patient 7. CT scan (bone windows) showing extensive fragmentation of the symphysis pubis and a small air pocket (anow) in the symphysis.
identified on bone window interrogation of the thoracoabdominopelvic CT scans of each patient. One patient had a bone scan which showed the symphysis pubis lesion to be solitary. Abscess cavities with or without air/fluid levels were present in six patients on CT (Figs 2 - 4 ) and in one at Table 2 - Key computed
Patient
tomographic
Fig. 2 - Patient 5. CT scan (bone windows) showing sclerosis and fragmentation of the symphysis pubis (arrow). Note the abscess cavity (asterisk) and thickened fight obturator internus muscle (O).
surgery prior to CT. The abscesses were directly adjacent to the area of bone destruction and, in five patients, small bowel was adherent to the abscess collection. Inflammatory soft tissue masses featured in five patients,
features
Solitary destruction of symphysis pubis
Soft tissue mass
1
+
+
2 3 4 5 6 7
+ + + + + +
+ + + +
Sinus~fistula
Abscess
Bowel associated with abscess
-
+
+
+ + + +
+ + -* + + +
+ -* + + +
* Emergency surgery had 1o be performed immediately prior to CT in this patient when an abscess was found to be involving the symphysis pubis with adherent loops of small bowel, one of which had perforated. 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
128
CLINICAL RADIOLOGY
Fig. 3 - Patient 1. CT scan (bone windows) showing sclerosis of the superior right pubic ramus with a fracture (straight arrow). Note the pelvic abscess (asterisk) and intimately related small bowel (curved arrow). (See Fig. 4a for lower section on this patient.)
Fig. 5 - Patient 4. CT scan (soft tissue settings) showing extensive soft tissue mass (m) around the symphysis pubis and symmetrical thickening of the anterior portions of the obturator internus muscles (white arrows).
which were symmetrical around the bone changes, but often extended to involve adjacent muscle groups particularly the obturator internus and the rectus abdominis muscles, leading to a uniform thickening of these muscles (Fig. 5). Although five patients had clinical evidence of a fistula, this was identified on CT in only four: two patients had CT sinograms (Fig. 6), one patient showed an enteric communication with the abscess and the fourth had a rectovaginal
(a)
(a)
(b) Fig. 4 - (a) Patient 1. CT scan on soft tissue settings showing abscess cavity (black asterisk) behind the symphysis pubis and extending into the right obturator foramen. Despite the soft tissue windows fragmentation of the symphysis can be seen. A surgical clip is also present in the pelvis. (b) Patient 4. CT scan on soft tissue settings demonstrating an abnormal gas collection (white asterisk) extending into the fragmented symphysis pubis
(arrow).
(b) Fig. 6 - (a, b) Patient 3. CT sinogram on bone settings showing contrast in the sinus (arrow) on the anterior abdominal wall extending towards loops of small bowel (a). At a lower level (b) contrast extends into the symphysis pubis and into the true pelvis (arrows). 9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
129
OSTEOMYELITIS OF THE SYMPHYSIS PUBIS
Table 3 - Clinical and laboratory data at time of osteomyeliti s Patient
Surgical findings
Bacteriology~histology Organism and site of isolation
Treatment
1
Pelvic abscess extending to symphysis pubis with vaginal fistula
Bacteroides and Enterococci (from peripubic abscess)
Fistula repair Abscess debridement Maintenance antibiotics
2
Abscess extending into pectineus muscle and symphysis pubis
Bone biopsy confirmed (right and left pubic rami)
Abscess drainage and curettage
3
Fistula from colon to thigh via pubic abscess
Bacteroides and Diphtheroids (from peripubic abscess)
Multiple abscess debridements
4
Small bowel perforation into pelvic abscess which communicated with symphysis pubis
Staph. aureus (from peripubic abscess)
Abscess drainage Small bowel resection
5
Abscess extending to symphysis pubis with vaginal fistula
Enterococci and Pseudomonas (from peripubic abscess)
Fistula repair Abscess debridement
6
Fistula to abdominal wall and left thigh with small bowel perforation and pelvic abscess involving symphysis pubis
Coliforms and group B Streptococci (from peripubic abscess)
Abscess debridement Small bowel resection
7
Recto-vagino abscess extending to symphysis pubis
Enterococci (from peripubic abscess)
Abscess drainages
fistula, which was demonstrable on CT with an adjacent abscess and adherent obstructed small bowel. The organisms isolated, histological results and treatment each patient received are recorded in Table 3. In six out of seven patients, the bacteria isolated were bowel organisms. Follow-up On follow-up (Table 4) two patients were well after treatment for their osteomyelitis. One patient had a recurrent abscess and septic arthritis of the left hip and is now on longterm antibiotics. One patient had further severe pelvic sepsis with multiple fistulae but has now completely recovered. This patient has had several laparotomies and the histology and bacteriology have shown only infection and radiation change with no evidence of tumottr. Three patients had died; at post-mortem one had pelvic sepsis, including symphysis pubis osteomyelitis, and there was small bowel obstruction with no evidence of tumour. One died from a myocardial infarction 2 years after treatment for osteomyelitis, at which time a post-mortem showed no tumour or pelvic sepsis. The third patient died of carcinomatosis after 12 months. DISCUSSION In patients who have received radiotherapy for cancer, the differentia/ diagnosis of a bone lesion typically rests
between a metastasis and radionecrosis. In our experience, osteomyelitis must be added to that differential in patients who have sustained symptomatic radiation effects, and this is important because effective treatment is available using a combination of surgical debridement and long-term antibiotics. Accepted diagnostic criteria for osteomye!itis include two out of three of the following: radiological changes, typical histological features or positive microbiological cultures [6,7]. Using these criteria, all of our patients can be diagnosed as having osteomyelitis. There are several clinical and radiological features common to our patient cohort. All had sustained severe pelvic radiation change that necessitated surgical intervention. There was a long time interval between the original radiotherapy and the onset of osteomyelitis and over 1 year between prior pelvic surgery and the onset of sepsis. The coexistence of lytic and sclerotic bone change symmetrically involving the pubic bones, directly associated with a pelvic abscess and, in some cases, with gas within the symphysis pubis or intestinal fistulae, were features suggestive of infection. Metastatic bone involvement was unlikely in our patients for several reasons. The lesion was solitary as indicated by normal CT bone window interrogation in all patients and a normal radionuclide bone scan in one patient. The destruction was symmetrical, affecting the bone on both sides of the joint space which would be most unusual for a solitary
Table 4 - Follow-up Patient
Post-osteomyelitis length of follow-up
Alive and well
Further pelvic sepsis
Dead
Post-mortem
+ +
Myocardial infarction. No tumour
+
Abdominopelvic sepsis including symphysis pubis osteomyelitis. No tumour
(years) 1
5
2 3 4 5 6
4 5 2 1 5
+ Including septic arthritis of left hip + +
+
Including multiple perineal fistulae without tumour at surgery 7
0.1
9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 126-130.
130
CLINICAL RADIOLOGY
metastasis. In addition, a minimum of 6 years had elapsed between treatment of the primary tumour and the development of the bone lesion that considerably reduces the likelihood of metastatic disease [8], which will occur within 5 years in 88% of patients with cervical cancer [9] and in 95% of patients with bladder cancer [10]. Cervical cancer bone metastases are almost invariably lyric [11] and bladder cancer bone metastases are usually lyric [12]. Therefore, the mixed lytic/sclerotic nature of the bone lesions in our patients would also mitigate against metastases. Following the introduction of mega-voltage radiotherapy, there has been a reduction in the absorbed bone dose helped by better collimated fields and changes in therapy regimens. This has resulted in a significant decrease in radionecrosis, although inevitably the bone will sustain minor radiation effects. Radionecrosis may result in osteopenia alone, or patchy osteopenia with sclerosis and there is an increased risk of fractures in radiation-affected bone. The changes are confined to the irradiated area and therefore may cross joint boundaries to affect multiple bones. There is little doubt that our patients do have some degree of radiation-induced bone changes but pure radionecrosis is not associated with a soft tissue mass or abscess formation [11] and the presence of soft tissue masses, fistulae and abscesses in our patients indicates that the dominant pathology is one of infection. The clinical and bacteriological features (particularly the intestinal origin of the infecting organisms in six out of seven patients) would suggest that the osteomyelitis results from visceral radiation damage causing local pelvic sepsis and direct spread to radiation-affected bone. Indeed, two patients had a pelvic small bowel perforation contributing to the local sepsis with histological evidence of radiation therapy effect in the resected bowel. Six out of seven patients responded to conventional treatment for osteomyelitis thereby providing additional support for the diagnosis. One patient was thought to have recurrent pelvic tumour by virtue of the symphysis pubis abnormality and managed accordingly. This patient developed small bowel obstruction and was then referred for clinical and radiological review. Unfortunately, the patient died and post-mortem demonstrated abdominal sepsis with
multiple abdomino-pelvic abscesses, and symphysis pubis osteomyelitis, but no evidence of tumour recurrence. These patients illustrate the need to consider an infective aetiology for solitary destruction of the symphysis pubis in combination with a soft tissue mass, abscess or fistula in patients who have had radical pelvic radiotherapy and are on long-term follow-up. Acknowledgements. We would like to thank Mr N.W. Clarke and Mr R. J. Barnard for permission to report these cases. We would also like to thank Mrs Kami Ramnarain for assisting in the preparation of the manuscript and the Department of Medical Illustration for photographic assistance. REFERENCES 1 Rosenthal RE, Spickard WA, Markham RD et al. Osteomyelitis of the symphysis pubis: a separate disease from osteitis pubis. Journal of Bone and Joint Surgery (Am) 1992;64:123-128. 2 Rowarth G. Osteomyelitis of the pubic bones and staphylococcal septicaemia complicating pregnancy. Journal of Obstetrics and Gynaecology (British Empire) 1940;47:213-216. 3 Lindeque BG, Mennen U. Infectious osteitis pubis. South African Medical Journal 1985;67:689-691. 4 Thompson IM, Marx AC. Conservative therapy of rectourethral fistula: five year follow up. Urology 1990;35:533-536. 5 Gun'ko RI, Krasnov AS. Radiation injuries of the bones during treatment of uterine cancer. Voprosy Onkologii (Leningrad) 1988; 34:1188-1195. 6 Waldvogel FA, Medoff G, Swartz MN. Osteomyelitis: a review of clinical features, therapuetic considerations and unusual aspects (first of three parts). New England Journal of Medicine 1970;282:198. 7 Burns JR, Gregory JG. Osteomyelitis of pubic symphysis after urologic surgery. Journal of Urology 1977;118:803-805. 8 Liebshitz HI. Radiation changes in bone. Seminars in Roentgenology 1994;29:15 -37. 9 Fagundes H, Perez CA, Grigsby PW et al. Distant metastases after irradiation alone in carcinoma of the uterine cervix. International Journal of Radiation, Oncology, Biology and Physics 1992;24:197 - 204. 10 Duncan W, Quilty PM. The results of a series of 963 patients with transitional cell carcinoma of the urinary bladder primarily treated by radical megavoltage x-ray therapy. Radiotherapy and Oncology 1986;7:299-310. 11 Yousem DM, Magid D, Scott W W et al. Treated invasive cervical carcinoma - - utility of CT in destinguishing between skeletal metastases and radiation necrosis. Clinical Imaging 1989;13:147-153. 12 Malawer MM, Delaney TF. Treatment of metastatic cancer to bone. In: deVita VT, Hellman S, Rosenberg SA, eds. Cancer." principles and practice ofoncology. Philadelphia: JB Lippincott, 1989:2298-2316.
9 1998 The Royal College of Radiologists, ClinicalRadiology, 53, 126-130.