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Delayed diagnosis of a primary psoas abscess mimicking septic arthritis of the hip
Delayed Diagnosis of a Primary Psoas Abscess Mimicking Septic Arthritis of the Hip By A. Toren, A. Ganel, D. Lotan, and M. Graif TeI-Hashomer, Israel
9 A 5-year-old boy presented with a limp, fever, and right hip pain of 72 hours" duration. An intensive workup of right hip pain synovitis failed to diagnose any local pathology. Delayed diagnosis of psoas abscess was made on the 12th day of hospitalization. A rapid recovery with no further complications followed surgical evacuation of the abscess. 9 1 9 8 9 b y Grune & S t r a t t o n , Inc.
INDEX WORDS: Psoas abscess; synovitis, hip.
A
POSITIVE "psoas sign" of hip flexion and pain on extension is a common finding in various affections of the hip joint in children. Children with transient synovitis of the hip or septic hips present with this sign. Psoas abscess may be overlooked because it is uncommon. Most reported cases have been diagnosed late. The purpose of this report is to describe one such case, and to review the various diagnostic procedures that help diagnose psoas abscess in children. CASE REPORT A 5-year-old boy with a fever, right hip pain, and a limp of three days' duration was hospitalized with a working diagnosis of a septic hip. In the 2 months prior to admission, he suffered from recurrent skin abscesses. Staphylococcus aureus was cultured on several occasions. One week prior to hospitalization, he had an upper respiratory tract infection. Upon admission, a physical examination showed his temperature
was 38.3~ and he was in good general condition. The right hip was flexed and externally rotated. Both passive and active motion of the leg elicited marked pain. Hyperextension of the right thigh, while lying on the left side, markedly accentuated his pain (positive psoas sign). A small skin abscess was noted over the posterior aspect of the right elbow. Radiographs of the spine, pelvis, and right femur were normal. Laboratory findings showed a WBC count of 16,600, with a normal differential. This ESR level was 50/80 and hemoglobin was 11.8 g%. An ultrasound of both hips (Fig 1) was normal; thus, no aspiration of the hip joint seemed indicated. With a diagnosis of possible transient synovitis, aspirin therapy was initiated for 5 days. Bacterial cultures from the elbow abscess grew Staphylococcus aureus. Blood cultures were negative. Gradually, the hip pain decreased; however, on the sixth day, the patient became febrile and his limp worsened. A deep abscess on the left buttock developed, and numbness of the right foot appeared. A 99mTc-MDP bone scan of the entire body was normal. An ultrasound examination of the hips showed a slight increase in the size of the right hip, 7 mm as compared with 5 mm on the left side, and a semisolid collection of 2.4 x 1.2 x 4 cm in the left buttock. Further laboratory findings were as follows: IgG 1,220 (normal value), IgA 182 (normal), IgM 284 (high), normal PPD, and a normal result on the nitro blue tetrazolium reduction test. Ga-citratrate scan demonstrated high uptake in the region of the left buttock outside the hip joint. Repeated blood cultures were negative; however, ampicillin treatment was initiated. On the 12th day, the child became toxic. His body temperature was 39~ Slight tenderness in the right upper and lower abdomen was noted. He had normal bowl sounds, no mass could be felt, and rectal examination was noncontributory. The ESR level was 70/100 and the WBC count was 25,500. The 5-day, 67Ga scan showed increased uptake in the right lower quadrant near the midline. An ultrasound examination of the abdomen showed a mass in the right psoas muscle (Fig 2). A computed tomography (CT) scan of the lower abdomen demonstrated a psoas abscess (Fig 3). An operation was performed on the child's 12th day of hospitalization. Through a retroperitoneal approach, the right psoas muscle was approached, from which 50 mL of psu was drained. Bacteriological cultures grew Staphylococcus aureus. A rapid recovery followed and the child was discharged on the 22nd day of hospitalization.
DISCUSSION
Secondary psoas abscess complicates various diseases of the retroperitoneum and of the peritoneal cavity. ] Included are appendicitis, inflammatory bowel
Fig 1. A longitudinal arthrosonogrsm of both hip joints shows normal and symmetrical distance of the joint capsule (large arrow) from the femoral bone (small arrows). Journal of Pediatric Surgery, Vol 24, No 2 (February), 1989: pp 227-228
From the Departments o f Pediatrics and Orthopedics, and the Division o f Diagnostic Ultrasound, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler School o f Medicine, Tel-Aviv University. Israel. Address reprint requests to A. Toren, MD, Department o f Pediatrics, The Chaim Sheba Medical Center, Tel-Hashomer 52621, Israel. 9 1989 by Grune & Stratton, Inc. 0022-3468/89/2402-0025503.00/0 227
228
TOREN ET AL
Fig 3. CT scan of the pelvis shows markedly enlarged right psoas muscle in which a translucent area with possible liquid is seen.
Fig 2. A transverse pelvic sonogram demonstrates anterior displacement of the right femoral nerve (large arrow) by the psoas abscess (small arrows). The left femoral nerve (large arrow) is located in a normal position. R, right; L, left.
disease, ] Crohn's disease, 2 pancreatitis, pyelonephritis, tuberculosis of the spine, and surgical procedures of the retroperitoneum. 3 Primary psoas abscess is rare and its pathogenesis is obscure. Suppurative lymphadenitis, posttraumatic hematoma formation with secondary infection, and hematogenous seeding have all been proposed as initial factors. 1 Less than 30 cases of primary psoas abscess in children have been published in the English litel ature. 4 In most cases (as in ours) Staphylococcus aureus has been the causing bacteria. This differs from cases with secondary psoas abscess in which gram-negative or anaerobic bacteria are found. 5 Our patient had multiple skin abscess including a gluteal abscess on the opposite side, and we postulated that hematogenous seeding of bacteria caused the psoas abscess. The clinical symptoms of psoas abscess are much tike those of hip joint disease, 4 ie, position of the hip in flexion and abduction, pain on motion of the hip, mainly extension and decreased range of motion as they appeared in our case. Attention and diagnostic efforts are usually misdirected to diagnose hip joint infection,
and the correct diagnosis is delayed. Hyperextension of the hip, as performed in the Thomas test (the opposite normal hip is fully flexed and the lower back is flat on the examining table, thus eliminating lumbar lordosis, and then extension of the affected leg), is painful in various affections of the hip joints. However, a positive psoas sign, ie, hyperextension performed while lying on the side, should alert the physician to possible psoas muscle disease. The course of delayed diagnosis seems common in psoas abscess. 5 The correct diagnosis of psoas abscess requires a high degree of suspicion as well as various diagnostic procedures. Plain x-rays of the abdomen may show prominence or bulging of the psoas shadow. An intravenous pyelogram can demonstrate a medially deviated ureter. However, ultrasound, CT scan, and 67Ga scan proved to be the most useful. 1'68 Our case illustrates the diagnosis using ultrasound and CT scan. Since ultrasound of the hip became popular in diagnosing hip joint effusions, 9 it is our belief that extending the ultrasonically investigated area to routinely screen the psoas muscle would markedly reduce the time lag prior to diagnosing psoas abscess. ACKNOWLEDGMENT
The authors thank Drs Avigadand Apter for their cooperation.
REFERENCES
1. Finnerty RU, Vordermark JS, Modarelli RO, et al: Primary psoas abscess: Case report and review of literature. J Urol 126:108109, 1981 2. Ramus NJ, Shorey BA: Crohn's disease and psoas abscess. Br Med J 3:574-575, 1975 3. KnobelB, SommerI, Swhartz G: Primary psoas abscess three years after ipsilateral nephrectomy.Infection 13:27-28, 1985 4. Hugh VF: Acute psoas abscess in children. Clin Pediatr 11:228-231, 1972 5. Hardcastle JD: Acute non-tuberculous psoas abscess. Report of 10 cases and reviewof the literature. Br J Surg 57:103-106, 1970
6. Feldberg MA, Koehler PR, Vanwaes PFGM. Psoas compartment disease studied by computedtomography.Radiology148:505512, 1983 7. Korobkin M, Callen PW, Filly RA, et al: Comparison of computed tomography, ultrasound and galium-67 scanning in the evaluation of suspected abdominal abscess. Radiology 129:89-90, 1978 8. Rails PW, BoswellW, Henderson R, et al: CT of inflammatory disease of the psoas muscle. Am J Radiol 134:767-770, 1980 9. WingstrandM: Transient synovitisof the hip in the child. Acta Orthop Scand 57:219, 1986 (suppl)
9 A 5-year-old boy presented with a limp, fever, and right hip pain of 72 hours" duration. An intensive workup of right hip pain synovitis failed to diagnose any local pathology. Delayed diagnosis of psoas abscess was made on the 12th day of hospitalization. A rapid recovery with no further complications followed surgical evacuation of the abscess. 9 1 9 8 9 b y Grune & S t r a t t o n , Inc.
INDEX WORDS: Psoas abscess; synovitis, hip.
A
POSITIVE "psoas sign" of hip flexion and pain on extension is a common finding in various affections of the hip joint in children. Children with transient synovitis of the hip or septic hips present with this sign. Psoas abscess may be overlooked because it is uncommon. Most reported cases have been diagnosed late. The purpose of this report is to describe one such case, and to review the various diagnostic procedures that help diagnose psoas abscess in children. CASE REPORT A 5-year-old boy with a fever, right hip pain, and a limp of three days' duration was hospitalized with a working diagnosis of a septic hip. In the 2 months prior to admission, he suffered from recurrent skin abscesses. Staphylococcus aureus was cultured on several occasions. One week prior to hospitalization, he had an upper respiratory tract infection. Upon admission, a physical examination showed his temperature
was 38.3~ and he was in good general condition. The right hip was flexed and externally rotated. Both passive and active motion of the leg elicited marked pain. Hyperextension of the right thigh, while lying on the left side, markedly accentuated his pain (positive psoas sign). A small skin abscess was noted over the posterior aspect of the right elbow. Radiographs of the spine, pelvis, and right femur were normal. Laboratory findings showed a WBC count of 16,600, with a normal differential. This ESR level was 50/80 and hemoglobin was 11.8 g%. An ultrasound of both hips (Fig 1) was normal; thus, no aspiration of the hip joint seemed indicated. With a diagnosis of possible transient synovitis, aspirin therapy was initiated for 5 days. Bacterial cultures from the elbow abscess grew Staphylococcus aureus. Blood cultures were negative. Gradually, the hip pain decreased; however, on the sixth day, the patient became febrile and his limp worsened. A deep abscess on the left buttock developed, and numbness of the right foot appeared. A 99mTc-MDP bone scan of the entire body was normal. An ultrasound examination of the hips showed a slight increase in the size of the right hip, 7 mm as compared with 5 mm on the left side, and a semisolid collection of 2.4 x 1.2 x 4 cm in the left buttock. Further laboratory findings were as follows: IgG 1,220 (normal value), IgA 182 (normal), IgM 284 (high), normal PPD, and a normal result on the nitro blue tetrazolium reduction test. Ga-citratrate scan demonstrated high uptake in the region of the left buttock outside the hip joint. Repeated blood cultures were negative; however, ampicillin treatment was initiated. On the 12th day, the child became toxic. His body temperature was 39~ Slight tenderness in the right upper and lower abdomen was noted. He had normal bowl sounds, no mass could be felt, and rectal examination was noncontributory. The ESR level was 70/100 and the WBC count was 25,500. The 5-day, 67Ga scan showed increased uptake in the right lower quadrant near the midline. An ultrasound examination of the abdomen showed a mass in the right psoas muscle (Fig 2). A computed tomography (CT) scan of the lower abdomen demonstrated a psoas abscess (Fig 3). An operation was performed on the child's 12th day of hospitalization. Through a retroperitoneal approach, the right psoas muscle was approached, from which 50 mL of psu was drained. Bacteriological cultures grew Staphylococcus aureus. A rapid recovery followed and the child was discharged on the 22nd day of hospitalization.
DISCUSSION
Secondary psoas abscess complicates various diseases of the retroperitoneum and of the peritoneal cavity. ] Included are appendicitis, inflammatory bowel
Fig 1. A longitudinal arthrosonogrsm of both hip joints shows normal and symmetrical distance of the joint capsule (large arrow) from the femoral bone (small arrows). Journal of Pediatric Surgery, Vol 24, No 2 (February), 1989: pp 227-228
From the Departments o f Pediatrics and Orthopedics, and the Division o f Diagnostic Ultrasound, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler School o f Medicine, Tel-Aviv University. Israel. Address reprint requests to A. Toren, MD, Department o f Pediatrics, The Chaim Sheba Medical Center, Tel-Hashomer 52621, Israel. 9 1989 by Grune & Stratton, Inc. 0022-3468/89/2402-0025503.00/0 227
228
TOREN ET AL
Fig 3. CT scan of the pelvis shows markedly enlarged right psoas muscle in which a translucent area with possible liquid is seen.
Fig 2. A transverse pelvic sonogram demonstrates anterior displacement of the right femoral nerve (large arrow) by the psoas abscess (small arrows). The left femoral nerve (large arrow) is located in a normal position. R, right; L, left.
disease, ] Crohn's disease, 2 pancreatitis, pyelonephritis, tuberculosis of the spine, and surgical procedures of the retroperitoneum. 3 Primary psoas abscess is rare and its pathogenesis is obscure. Suppurative lymphadenitis, posttraumatic hematoma formation with secondary infection, and hematogenous seeding have all been proposed as initial factors. 1 Less than 30 cases of primary psoas abscess in children have been published in the English litel ature. 4 In most cases (as in ours) Staphylococcus aureus has been the causing bacteria. This differs from cases with secondary psoas abscess in which gram-negative or anaerobic bacteria are found. 5 Our patient had multiple skin abscess including a gluteal abscess on the opposite side, and we postulated that hematogenous seeding of bacteria caused the psoas abscess. The clinical symptoms of psoas abscess are much tike those of hip joint disease, 4 ie, position of the hip in flexion and abduction, pain on motion of the hip, mainly extension and decreased range of motion as they appeared in our case. Attention and diagnostic efforts are usually misdirected to diagnose hip joint infection,
and the correct diagnosis is delayed. Hyperextension of the hip, as performed in the Thomas test (the opposite normal hip is fully flexed and the lower back is flat on the examining table, thus eliminating lumbar lordosis, and then extension of the affected leg), is painful in various affections of the hip joints. However, a positive psoas sign, ie, hyperextension performed while lying on the side, should alert the physician to possible psoas muscle disease. The course of delayed diagnosis seems common in psoas abscess. 5 The correct diagnosis of psoas abscess requires a high degree of suspicion as well as various diagnostic procedures. Plain x-rays of the abdomen may show prominence or bulging of the psoas shadow. An intravenous pyelogram can demonstrate a medially deviated ureter. However, ultrasound, CT scan, and 67Ga scan proved to be the most useful. 1'68 Our case illustrates the diagnosis using ultrasound and CT scan. Since ultrasound of the hip became popular in diagnosing hip joint effusions, 9 it is our belief that extending the ultrasonically investigated area to routinely screen the psoas muscle would markedly reduce the time lag prior to diagnosing psoas abscess. ACKNOWLEDGMENT
The authors thank Drs Avigadand Apter for their cooperation.
REFERENCES
1. Finnerty RU, Vordermark JS, Modarelli RO, et al: Primary psoas abscess: Case report and review of literature. J Urol 126:108109, 1981 2. Ramus NJ, Shorey BA: Crohn's disease and psoas abscess. Br Med J 3:574-575, 1975 3. KnobelB, SommerI, Swhartz G: Primary psoas abscess three years after ipsilateral nephrectomy.Infection 13:27-28, 1985 4. Hugh VF: Acute psoas abscess in children. Clin Pediatr 11:228-231, 1972 5. Hardcastle JD: Acute non-tuberculous psoas abscess. Report of 10 cases and reviewof the literature. Br J Surg 57:103-106, 1970
6. Feldberg MA, Koehler PR, Vanwaes PFGM. Psoas compartment disease studied by computedtomography.Radiology148:505512, 1983 7. Korobkin M, Callen PW, Filly RA, et al: Comparison of computed tomography, ultrasound and galium-67 scanning in the evaluation of suspected abdominal abscess. Radiology 129:89-90, 1978 8. Rails PW, BoswellW, Henderson R, et al: CT of inflammatory disease of the psoas muscle. Am J Radiol 134:767-770, 1980 9. WingstrandM: Transient synovitisof the hip in the child. Acta Orthop Scand 57:219, 1986 (suppl)