- Email: [email protected]
MR Findings in Pulmonary Hypertrophic Osteoarthropathy
72
CLINICAL RADIOLOGY
bone marrow cavities (bone marrow failure, hepatosplenomegaly). Seventy per cent of patients die by 6 years of age [3]. Therapy with high dose steroids [4] or interferon gamma [5] may improve symptoms but bone marrow transplantation is the only curative procedure [6]. The densely sclerotic bone of osteopetrosis is brittle and susceptible to fracture. In infantile osteopetrosis two types of fractures are recognized. These are diaphyseal or metaphyseal fractures which are usually transverse and only minimally displaced, or epiphyseal fracture separation [1], and usually occur in the lower limbs [7]. In our patient, bilateral transverse acromial fractures were detected on a chest radiograph following a grand mal seizure. Acromial fractures are rare at any age but when seen in young children are considered to be a strong indicator of child abuse [8,9]. In older children and adults they are commonly due to accidental trauma [10]. Bilateral acromial fractures have also been described as an unusual complication and poor prognostic sign of severe neonatal tetanus [11]. In this condition, spontaneous isometric muscle contraction results in avulsion of the acromion at the site of origin of the deltoid muscle. During foetal life, the body and spine of the scapula ossify from a single primary centre. Rarely, the lateral aspect of the spine of the scapula, which forms the root of the acromion, arises from a separate ossification centre. Failure of fusion of these ossification centres of the acromial root may simulate a fracture [12,13]. In view of the association of acromial fractures with infant abuse, recognition of this variant is important to avoid confusion with inflicted injury. A developmental anomaly is excluded in our case by the previously normal radiographs. In adults, fractures and dislocations around the limb girdles and spinal column are recognized complications of acute muscular contraction in seizures and electrocution, and are usually bilateral and symmetrical [14]. Uncoordinated generalized muscular contractions during a convulsive episode disturbs the stability of the shoulder joint and injury results in the direction of the predominant muscular action.
In our patient, we postulate that acute deltoid muscle contraction against structurally weak bone has resulted in bilateral fractures of the acromion at the sites of muscular attachment. We believe this to be the first report of bilateral acromial fractures complicating a grand mal convulsion.
REFERENCES 1 Shapiro F. Osteopetrosis. Current clinical considerations. Clin Orthop 1993;294:34–44. 2 Marks SC Jr. Congenital osteopetrotic mutations as probes of the origin, structure and function of osteoclasts. Clin Orthop 1984;189:239–263. 3 Gerritsen EJ, Vossen JM, van Loo IH et al. Autosomal recessive osteopetrosis: variability of findings at diagnosis and during the natural course. Pediatrics 1994;93:247–253. 4 Ozsoylu S. Megadose methylprednisolone treatment for malignant osteopetrosis. Eur J Pediatr 1994;153:779–780. 5 Key LL Jr, Rodriguiz RM, Willi SM et al. Long term treatment of osteopetrosis with recombinant human interferon gamma. N Engl J Med 1995;332:1594–1599. 6 Gerritsen EJ, Vossen JM, Fasth A et al. Bone marrow transplantation for autosomal recessive osteopetrosis. A report from the Working Party on Inborn Errors of the European Bone Marrow Transplantation Group. J Pediatr 1994;125:896–902. 7 Dahl N, Holmgren G, Holmberg S et al. Fracture patterns in malignant osteopetrosis (Albers-Schonberg disease). Arch Orthop Trauma Surg 1992;111:121–123. 8 Kogutt MS, Swischuk LE, Fagan CJ. Pattern of injury and significance of uncommon fractures in the battered child syndrome. Am J Roent 1974;121:143–149. 9 Kleinman PK. Diagnostic imaging of infant abuse. Am J Roent 1990; 155:703–712. 10 Kuhn JE, Blasier RB, Carpenter JE. Fracture of the acromion process: a proposed classification system. J Orthop Trauma 1994;8:6–13. 11 Kalideen JM, Satyapal KS. Fractures of the acromium in tetanus neonatorum. Clin Radiol 1994;49:563–565. 12 Kleinman PK, Spevak MR. Variation in acromial ossification simulating infant abuse in victims of Sudden Infant Death Syndrome. Pediatr Radiol 1991;180:185–187. 13 Currarino G, Prescott P. Fractures of the acromion in young children and a description of a variant in acromial ossification which may mimic a fracture. Pediatr Radiol 1994;24:251–255. 14 Brown RJ. Bilateral dislocation of the shoulders. Injury 1984;15:267– 273.
MR Findings in Pulmonary Hypertrophic Osteoarthropathy A. CAPE L AST E GUI, E . AST I GARRAGA and C. GARCI´ A-IT URRASPE* OSATEK Magnetic Resonance, Unit of Galdacano and *Department of Radiology, Galdacano Hospital, Bizkala, Spain
We describe a case of pulmonary hypertrophic osteoarthropathy (PHO) diagnosed after magnetic resonance (MR) of the lower extremities. Classic radiographic descriptions of this syndrome refer only to generalized periostitis, but involvement of soft tissues should also be considered if a MR is performed. Correspondence to: Dr Ana Capelastegui, Resonancia Magne´tica OSATEK, Hospital de Galdacano, Barrio Labeaga s/n, 48960 Vizcaya, Spain.
CASE REPORT A 55-year-old male smoker was referred for MR examination of his right knee because of a 1 month history of swelling and continuous pain. The pain was worse during the night and was not relieved by movement. He also complained of swelling, tenderness and pain on his four extremities, especially about the articulations, and a burning sensation in the fingertips. Examination showed digital clubbing. MR of the right knee (Fig. 1) demonstrated a fairly well-defined extensive soft-tissue swelling adjacent to the femoral cortex, with a high signal intensity on T2-weighted images and an heterogeneous signal
CASE REPORTS
73
Fig. 1 – MR images of the right knee obtained with a surface coil. Top: axial images at the same level of the distal femoral diaphysis, T1WI (440/12) on the left, and STIR (6320/60/140) on the right. Bottom, left: coronal T2WI image (3020/96) with a fat-saturation pulse. Bottom, right: sagittal STIR (5056/60/140). Axial images show the periosteal reaction, identified as a thin hypointense line (arrowheads) separated from the cortex, and the soft tissue mass (arrows) surrounding the femur and anteriorly displacing the pre-femoral fat. The periosteal reaction (arrowheads) is also demonstrated on sagittal and coronal images. Coronal image also shows the high intensity of the soft tissues surrounding the distal femur. Oedema at the vastus intermedius (asterisk) is clearly seen on the sagittal image; also note synovial effusion.
Fig. 2 – Axial STIR (5056/60/140) images of both extremities using the body coil at the thighs (top) and at the distal calves (bottom). A thin band of hyperintensity surrounds the bones, extending to the intermuscular septa (arrows). Also note hyperintensity of the vastus intermedius (asterisk). Both extremities are affected in an asymmetrical fashion, the right side being more extensively involved.
74
CLINICAL RADIOLOGY
Fig. 3 – Radiological findings: anteroposterior view of the distal right femur shows periosteal new bone along the shaft of the femur that correlates closely with MR findings (see Fig. 1 – top left).
intensity (high to low) on T1-weighted images. A fine hypointense line surrounding the femur and separated from the cortex on T2-weighted images by a thin band of hyperintensity was considered to represent an elevated periosteum. No evidence of medullary or cortical involvement was identified. As we could not find an upper or lower limit, the examination was extended to the whole lower extremity, using the body coil (Fig. 2). The paraosseous soft-tissue swelling was followed along the right femur, sparing the epiphyseal regions. The intermuscular septa of the quadriceps and the vastus intermedius showed high signal intensity on T2-weighted images. In the calf, the high signal surrounded the fibula and tibia. Similar findings, but less pronounced, were present in the contralateral extremity. The clinical picture and the MR findings were suggestive of PHO. Plain radiographs confirmed this diagnosis, revealing a generalized periostitis along the diaphysis and metaphysis of every long bone in the four extremities. The changes in the distal right femur (Fig. 3) consisted of a solid undulating periosteal reaction. Radiograph of the hands demonstrated a single periosteal elevation at the first metacarpals, and an irregular cortical thickening on the proximal and middle phalanxes. A chest radiograph demonstrated a 5-cm pulmonary mass in the 6th segment of the left lung which proved to be a poorly differentiated adenocarcinoma after CT-guided biopsy.
DISCUSSION
Hypertrophic osteoarthropathy (HO) is a clinicoradiological syndrome characterized by the triad of periostitis, digital
clubbing and painful swollen joints [1–3]. The syndrome may be primary, but the majority of cases are secondary. Secondary HO is termed PHO because the most commonly associated conditions are pulmonary (lung carcinoma being the leading cause in adults). The wide variety of conditions reported to cause HO make it difficult to find a common theory to explain the pathogenesis of this entity. A neurogenic mechanism has been proposed from the observation that HO may regress after vagotomy [1,2]. Recently, some investigators have proposed that HO changes may be due to the peripheral impaction of megakaryocytes and platelets clumps in the fingers and toes [4,5]. Diagnosis of PHO is based on clinical presentation and radiological demonstration of diffuse periostitis. Articular symptoms include pain, tenderness and swelling; synovial effusions are not infrequent [6]. Radiographically, a generalized periosteal reaction is the hallmark of the disease. Periostitis appears in the diaphyses and metaphyses of long bones, sparing the epiphyses (unlike primary HO), usually as a simple smooth elevation of the periosteum. To our knowledge, MR appearance of PHO has not been described previously. MR showed two main findings: the softtissue changes and the periosteal reaction. The former consisted of muscular and septal oedema with extensive soft-tissue swelling surrounding the femur, attached to the cortex, but not involving the bone itself, with high signal on T2-weighted and STIR images. These features are consistent with an inflammatory process, probably highly vascularized and similar to reactive oedema or fibrovascular proliferation. MR detection of periosteal reactions is not reliable, but in this case it was easily identified using a surface coil as a wavy thin hypointense line surrounding the cortex that correlated closely with radiographic findings. MR findings in this case demonstrate that in addition to the obvious osseous changes there are significant changes in the soft-tissue elements which are not as well appreciated using other diagnostic modalities. We believe that this soft-tissue involvement represents an inflammatory reaction that probably occurs in PHO. Support of this theory is provided with the following arguments, although we are unable to pathologically document these changes. Experimental studies in PHO have demonstrated an intense overgrowth of a vascular connective tissue surrounding the bony structures [1]. Periarticular soft-tissue swelling is a common clinical finding in PHO that can not be only explained by the periostitis and the synovial effusions. In this case, the degree of soft-tissue involvement detected on MR correlated with the severity and location of symptoms referred by the patient. In conclusion, MR of the lower extremities in this case of PHO demonstrated a generalized periosteal reaction, a paraosseous soft-tissue swelling and muscular or septal oedema. The improved sensitivity of MR in the detection of softtissue reactive changes may suggest an erroneous diagnosis if this is the first imaging technique used; malignancy and infectious diseases should be considered in the differential diagnosis. An awareness of the findings in this condition is useful in evaluating MR images of the musculoskeletal system.
75
CASE REPORTS
REFERENCES 1 Resnick D, Niwayama G. Enostosis, hyperostosis and periostitis. In: Resnick D, Niwayama G, eds. Diagnosis of Bone and Joint Disorders. Philadelphia, USA: W.B. Saunders Company, 1988:4097– 4115. 2 Greenfield GB. Cardinal roentgen features. In: Greenfield GB, ed. Radiology of Bone Diseases. Philadelphia, USA: J.B. Lippincott Company, 1990:405–578.
3 Wilner D. Periosteal and proliferative disorders. In: Wilner D, ed. Radiology of Bone Tumours and Allied Disorders. Philadelphia, USA: W.B. Saunders Company, 1982:1792–1842. 4 Dickinson CJ. The aetiology of clubbing and hypertrophic osteoarthropathy. Eur J Clin Invest 1993;23:330–338. 5 Martinez-Lavin J. Pathogenesis of hypertrophic osteoarhropathy. Clin Exp Rheumatol 1992;10:49–50. 6 Pineda C. Diagnostic imaging in hypertrophic osteoarthropathy. Clin Exp Rheumatol 1992; 10:27–33.
Intraluminal Thrombus of the Ascending Aorta with Systemic Embolism Detected by Spiral CT S. D . QAN ADL I, A . S. RANGHE ARD, P. L ACOMBE Department of Radiology, University Rene´ Descartes-Paris V, Ambroise Pare´ Hospital, Boulogne, France
Aortic thrombus without aneurysm as a source of systemic embolism is a rare entity that is little documented. It is usually described in the abdominal aorta [1–3] or in the aortic arch [4– 9]. Intraluminal thrombus (IT) in the aorta is mostly attributed to atherosclerosis [1,5–7,10] or to previous heparin therapy [2,11]. We report two unusual cases of IT of the ascending aorta diagnosed by spiral computed tomography (CT) and managed by anticoagulation therapy.
approach in order to avoid potential thrombus mobilization, and because of the reported high risk of catheter-related emboli in similar conditions [12]. The mass showed the typical features of thrombus, both on CT and on ultrasound examination. In addition, CT showed a limited left renal infarction. The patient was treated with intravenous heparin IV for one week (1000 IU/h) followed by warfarin therapy. The clinical course was favourable with complete disappearance of the thrombus 3 weeks later (Fig. 1d). There has been no recurrence of thromboembolism during 15 months follow-up.
CASE REPORTS
Case 2
Case 1
A 50-year-old woman was admitted with acute ischaemia of the left leg. She had no history of ischaemic heart disease, hypertension, vasculopathy, thromboembolic disease or malignancy. She had not received heparin previously. Smoking was her only cardiovascular risk factor. Angiography showed emboli in the left tibio-fibular trunk and in the right fibular artery without severe atherosclerosis. The patient received intravenous heparin. Spiral CT of the aorta performed on the third day showed an intraluminal filling defect in the ascending aorta (Fig. 2a). No severe atherosclerosis or evidence of intimal dissection was detected. TOE, performed 3 h previously, was normal. CT findings were confirmed by DSA of the thoracic aorta (Fig. 2b) following contrast injection into the pulmonary artery. Continuing heparin therapy resulted in resolution of the thrombus, and spiral CT performed 1 week later did not reveal any filling defect. At the time of discharge the patient was asymptomatic with no recurrence of thromboembolism on 6 months follow-up.
A 62-year-old woman was admitted to the hospital for acute ischaemia of the left hand evolving over 24 h. Six weeks previously she experienced subacute ischaemia of the right leg which spontaneously resolved. Doppler ultrasound of the left arm demonstrated an occlusion of the left brachial artery at its medial third, treated by embolectomy using a Fogarty catheter. The patient had no cardiovascular risk factors. She was normotensive and the heart was in normal sinus rhythm. Electrocardiogram, chest radiography and laboratory tests including coagulation (fibrinogen, prothrombin time, platelet count, bleeding time, dimer test, protein C, protein S, antithrombin III), and immunological studies (antinuclear and anticardiolipin antibodies, lupus anticoagulant) were normal. Two-dimensional echocardiography, performed on the second hospital day, showed normal cardiac contractility and no evidence of valvular disease or of thrombus in the cardiac cavities. Spiral CT of the aorta was performed on the third hospital day using a CT Twin Flash system (Elscint, Haifa, Israel) with collimation of 2 × 5 mm and a pitch of 1.5 (effective slice thickness: 5.5 mm). Enhanced images (150 ml of 25% iodinated contrast material at 4 ml/s) showed a large filling defect in the ascending aorta extending towards the aortic arch (Fig. 1a). Unenhanced CT images detected subtle irregularity of the left posterior wall of the ascending aorta with a calcified component indicative of atherosclerotic plaque (Fig. 1b). Transoesophageal echocardiography (TOE) and digital subtraction aortography (DSA) confirmed a pedunculated and highly mobile endoluminal aortic mass arising from the posterior wall of the ascending aorta (Fig. 1c). DSA was performed by pulmonary artery Author for correspondence and guarantor of study: Dr S. D. Qanadli, Service de Radiologie, Hoˆpital Ambroise Pare´, 9 avenue Charles de Gaulle, 92104 Boulogne Cedex, France.
DISCUSSION
Thrombus of the non-aneurysmal aorta is a known entity, previously reported to be a source of emboli producing arterial vascular occlusion of peripheral vessels, mesenteric, splenic or renal arteries [1,3,5–10,13–16]. Most of the reported aortic thrombi were located in the aortic arch [6–9], the descending thoracic aorta [10,13] and more frequently in the abdominal aorta from the tenth thoracic vertebra to the aortic bifurcation [1,3]. The ascending aorta is an uncommon location for IT.
CLINICAL RADIOLOGY
bone marrow cavities (bone marrow failure, hepatosplenomegaly). Seventy per cent of patients die by 6 years of age [3]. Therapy with high dose steroids [4] or interferon gamma [5] may improve symptoms but bone marrow transplantation is the only curative procedure [6]. The densely sclerotic bone of osteopetrosis is brittle and susceptible to fracture. In infantile osteopetrosis two types of fractures are recognized. These are diaphyseal or metaphyseal fractures which are usually transverse and only minimally displaced, or epiphyseal fracture separation [1], and usually occur in the lower limbs [7]. In our patient, bilateral transverse acromial fractures were detected on a chest radiograph following a grand mal seizure. Acromial fractures are rare at any age but when seen in young children are considered to be a strong indicator of child abuse [8,9]. In older children and adults they are commonly due to accidental trauma [10]. Bilateral acromial fractures have also been described as an unusual complication and poor prognostic sign of severe neonatal tetanus [11]. In this condition, spontaneous isometric muscle contraction results in avulsion of the acromion at the site of origin of the deltoid muscle. During foetal life, the body and spine of the scapula ossify from a single primary centre. Rarely, the lateral aspect of the spine of the scapula, which forms the root of the acromion, arises from a separate ossification centre. Failure of fusion of these ossification centres of the acromial root may simulate a fracture [12,13]. In view of the association of acromial fractures with infant abuse, recognition of this variant is important to avoid confusion with inflicted injury. A developmental anomaly is excluded in our case by the previously normal radiographs. In adults, fractures and dislocations around the limb girdles and spinal column are recognized complications of acute muscular contraction in seizures and electrocution, and are usually bilateral and symmetrical [14]. Uncoordinated generalized muscular contractions during a convulsive episode disturbs the stability of the shoulder joint and injury results in the direction of the predominant muscular action.
In our patient, we postulate that acute deltoid muscle contraction against structurally weak bone has resulted in bilateral fractures of the acromion at the sites of muscular attachment. We believe this to be the first report of bilateral acromial fractures complicating a grand mal convulsion.
REFERENCES 1 Shapiro F. Osteopetrosis. Current clinical considerations. Clin Orthop 1993;294:34–44. 2 Marks SC Jr. Congenital osteopetrotic mutations as probes of the origin, structure and function of osteoclasts. Clin Orthop 1984;189:239–263. 3 Gerritsen EJ, Vossen JM, van Loo IH et al. Autosomal recessive osteopetrosis: variability of findings at diagnosis and during the natural course. Pediatrics 1994;93:247–253. 4 Ozsoylu S. Megadose methylprednisolone treatment for malignant osteopetrosis. Eur J Pediatr 1994;153:779–780. 5 Key LL Jr, Rodriguiz RM, Willi SM et al. Long term treatment of osteopetrosis with recombinant human interferon gamma. N Engl J Med 1995;332:1594–1599. 6 Gerritsen EJ, Vossen JM, Fasth A et al. Bone marrow transplantation for autosomal recessive osteopetrosis. A report from the Working Party on Inborn Errors of the European Bone Marrow Transplantation Group. J Pediatr 1994;125:896–902. 7 Dahl N, Holmgren G, Holmberg S et al. Fracture patterns in malignant osteopetrosis (Albers-Schonberg disease). Arch Orthop Trauma Surg 1992;111:121–123. 8 Kogutt MS, Swischuk LE, Fagan CJ. Pattern of injury and significance of uncommon fractures in the battered child syndrome. Am J Roent 1974;121:143–149. 9 Kleinman PK. Diagnostic imaging of infant abuse. Am J Roent 1990; 155:703–712. 10 Kuhn JE, Blasier RB, Carpenter JE. Fracture of the acromion process: a proposed classification system. J Orthop Trauma 1994;8:6–13. 11 Kalideen JM, Satyapal KS. Fractures of the acromium in tetanus neonatorum. Clin Radiol 1994;49:563–565. 12 Kleinman PK, Spevak MR. Variation in acromial ossification simulating infant abuse in victims of Sudden Infant Death Syndrome. Pediatr Radiol 1991;180:185–187. 13 Currarino G, Prescott P. Fractures of the acromion in young children and a description of a variant in acromial ossification which may mimic a fracture. Pediatr Radiol 1994;24:251–255. 14 Brown RJ. Bilateral dislocation of the shoulders. Injury 1984;15:267– 273.
MR Findings in Pulmonary Hypertrophic Osteoarthropathy A. CAPE L AST E GUI, E . AST I GARRAGA and C. GARCI´ A-IT URRASPE* OSATEK Magnetic Resonance, Unit of Galdacano and *Department of Radiology, Galdacano Hospital, Bizkala, Spain
We describe a case of pulmonary hypertrophic osteoarthropathy (PHO) diagnosed after magnetic resonance (MR) of the lower extremities. Classic radiographic descriptions of this syndrome refer only to generalized periostitis, but involvement of soft tissues should also be considered if a MR is performed. Correspondence to: Dr Ana Capelastegui, Resonancia Magne´tica OSATEK, Hospital de Galdacano, Barrio Labeaga s/n, 48960 Vizcaya, Spain.
CASE REPORT A 55-year-old male smoker was referred for MR examination of his right knee because of a 1 month history of swelling and continuous pain. The pain was worse during the night and was not relieved by movement. He also complained of swelling, tenderness and pain on his four extremities, especially about the articulations, and a burning sensation in the fingertips. Examination showed digital clubbing. MR of the right knee (Fig. 1) demonstrated a fairly well-defined extensive soft-tissue swelling adjacent to the femoral cortex, with a high signal intensity on T2-weighted images and an heterogeneous signal
CASE REPORTS
73
Fig. 1 – MR images of the right knee obtained with a surface coil. Top: axial images at the same level of the distal femoral diaphysis, T1WI (440/12) on the left, and STIR (6320/60/140) on the right. Bottom, left: coronal T2WI image (3020/96) with a fat-saturation pulse. Bottom, right: sagittal STIR (5056/60/140). Axial images show the periosteal reaction, identified as a thin hypointense line (arrowheads) separated from the cortex, and the soft tissue mass (arrows) surrounding the femur and anteriorly displacing the pre-femoral fat. The periosteal reaction (arrowheads) is also demonstrated on sagittal and coronal images. Coronal image also shows the high intensity of the soft tissues surrounding the distal femur. Oedema at the vastus intermedius (asterisk) is clearly seen on the sagittal image; also note synovial effusion.
Fig. 2 – Axial STIR (5056/60/140) images of both extremities using the body coil at the thighs (top) and at the distal calves (bottom). A thin band of hyperintensity surrounds the bones, extending to the intermuscular septa (arrows). Also note hyperintensity of the vastus intermedius (asterisk). Both extremities are affected in an asymmetrical fashion, the right side being more extensively involved.
74
CLINICAL RADIOLOGY
Fig. 3 – Radiological findings: anteroposterior view of the distal right femur shows periosteal new bone along the shaft of the femur that correlates closely with MR findings (see Fig. 1 – top left).
intensity (high to low) on T1-weighted images. A fine hypointense line surrounding the femur and separated from the cortex on T2-weighted images by a thin band of hyperintensity was considered to represent an elevated periosteum. No evidence of medullary or cortical involvement was identified. As we could not find an upper or lower limit, the examination was extended to the whole lower extremity, using the body coil (Fig. 2). The paraosseous soft-tissue swelling was followed along the right femur, sparing the epiphyseal regions. The intermuscular septa of the quadriceps and the vastus intermedius showed high signal intensity on T2-weighted images. In the calf, the high signal surrounded the fibula and tibia. Similar findings, but less pronounced, were present in the contralateral extremity. The clinical picture and the MR findings were suggestive of PHO. Plain radiographs confirmed this diagnosis, revealing a generalized periostitis along the diaphysis and metaphysis of every long bone in the four extremities. The changes in the distal right femur (Fig. 3) consisted of a solid undulating periosteal reaction. Radiograph of the hands demonstrated a single periosteal elevation at the first metacarpals, and an irregular cortical thickening on the proximal and middle phalanxes. A chest radiograph demonstrated a 5-cm pulmonary mass in the 6th segment of the left lung which proved to be a poorly differentiated adenocarcinoma after CT-guided biopsy.
DISCUSSION
Hypertrophic osteoarthropathy (HO) is a clinicoradiological syndrome characterized by the triad of periostitis, digital
clubbing and painful swollen joints [1–3]. The syndrome may be primary, but the majority of cases are secondary. Secondary HO is termed PHO because the most commonly associated conditions are pulmonary (lung carcinoma being the leading cause in adults). The wide variety of conditions reported to cause HO make it difficult to find a common theory to explain the pathogenesis of this entity. A neurogenic mechanism has been proposed from the observation that HO may regress after vagotomy [1,2]. Recently, some investigators have proposed that HO changes may be due to the peripheral impaction of megakaryocytes and platelets clumps in the fingers and toes [4,5]. Diagnosis of PHO is based on clinical presentation and radiological demonstration of diffuse periostitis. Articular symptoms include pain, tenderness and swelling; synovial effusions are not infrequent [6]. Radiographically, a generalized periosteal reaction is the hallmark of the disease. Periostitis appears in the diaphyses and metaphyses of long bones, sparing the epiphyses (unlike primary HO), usually as a simple smooth elevation of the periosteum. To our knowledge, MR appearance of PHO has not been described previously. MR showed two main findings: the softtissue changes and the periosteal reaction. The former consisted of muscular and septal oedema with extensive soft-tissue swelling surrounding the femur, attached to the cortex, but not involving the bone itself, with high signal on T2-weighted and STIR images. These features are consistent with an inflammatory process, probably highly vascularized and similar to reactive oedema or fibrovascular proliferation. MR detection of periosteal reactions is not reliable, but in this case it was easily identified using a surface coil as a wavy thin hypointense line surrounding the cortex that correlated closely with radiographic findings. MR findings in this case demonstrate that in addition to the obvious osseous changes there are significant changes in the soft-tissue elements which are not as well appreciated using other diagnostic modalities. We believe that this soft-tissue involvement represents an inflammatory reaction that probably occurs in PHO. Support of this theory is provided with the following arguments, although we are unable to pathologically document these changes. Experimental studies in PHO have demonstrated an intense overgrowth of a vascular connective tissue surrounding the bony structures [1]. Periarticular soft-tissue swelling is a common clinical finding in PHO that can not be only explained by the periostitis and the synovial effusions. In this case, the degree of soft-tissue involvement detected on MR correlated with the severity and location of symptoms referred by the patient. In conclusion, MR of the lower extremities in this case of PHO demonstrated a generalized periosteal reaction, a paraosseous soft-tissue swelling and muscular or septal oedema. The improved sensitivity of MR in the detection of softtissue reactive changes may suggest an erroneous diagnosis if this is the first imaging technique used; malignancy and infectious diseases should be considered in the differential diagnosis. An awareness of the findings in this condition is useful in evaluating MR images of the musculoskeletal system.
75
CASE REPORTS
REFERENCES 1 Resnick D, Niwayama G. Enostosis, hyperostosis and periostitis. In: Resnick D, Niwayama G, eds. Diagnosis of Bone and Joint Disorders. Philadelphia, USA: W.B. Saunders Company, 1988:4097– 4115. 2 Greenfield GB. Cardinal roentgen features. In: Greenfield GB, ed. Radiology of Bone Diseases. Philadelphia, USA: J.B. Lippincott Company, 1990:405–578.
3 Wilner D. Periosteal and proliferative disorders. In: Wilner D, ed. Radiology of Bone Tumours and Allied Disorders. Philadelphia, USA: W.B. Saunders Company, 1982:1792–1842. 4 Dickinson CJ. The aetiology of clubbing and hypertrophic osteoarthropathy. Eur J Clin Invest 1993;23:330–338. 5 Martinez-Lavin J. Pathogenesis of hypertrophic osteoarhropathy. Clin Exp Rheumatol 1992;10:49–50. 6 Pineda C. Diagnostic imaging in hypertrophic osteoarthropathy. Clin Exp Rheumatol 1992; 10:27–33.
Intraluminal Thrombus of the Ascending Aorta with Systemic Embolism Detected by Spiral CT S. D . QAN ADL I, A . S. RANGHE ARD, P. L ACOMBE Department of Radiology, University Rene´ Descartes-Paris V, Ambroise Pare´ Hospital, Boulogne, France
Aortic thrombus without aneurysm as a source of systemic embolism is a rare entity that is little documented. It is usually described in the abdominal aorta [1–3] or in the aortic arch [4– 9]. Intraluminal thrombus (IT) in the aorta is mostly attributed to atherosclerosis [1,5–7,10] or to previous heparin therapy [2,11]. We report two unusual cases of IT of the ascending aorta diagnosed by spiral computed tomography (CT) and managed by anticoagulation therapy.
approach in order to avoid potential thrombus mobilization, and because of the reported high risk of catheter-related emboli in similar conditions [12]. The mass showed the typical features of thrombus, both on CT and on ultrasound examination. In addition, CT showed a limited left renal infarction. The patient was treated with intravenous heparin IV for one week (1000 IU/h) followed by warfarin therapy. The clinical course was favourable with complete disappearance of the thrombus 3 weeks later (Fig. 1d). There has been no recurrence of thromboembolism during 15 months follow-up.
CASE REPORTS
Case 2
Case 1
A 50-year-old woman was admitted with acute ischaemia of the left leg. She had no history of ischaemic heart disease, hypertension, vasculopathy, thromboembolic disease or malignancy. She had not received heparin previously. Smoking was her only cardiovascular risk factor. Angiography showed emboli in the left tibio-fibular trunk and in the right fibular artery without severe atherosclerosis. The patient received intravenous heparin. Spiral CT of the aorta performed on the third day showed an intraluminal filling defect in the ascending aorta (Fig. 2a). No severe atherosclerosis or evidence of intimal dissection was detected. TOE, performed 3 h previously, was normal. CT findings were confirmed by DSA of the thoracic aorta (Fig. 2b) following contrast injection into the pulmonary artery. Continuing heparin therapy resulted in resolution of the thrombus, and spiral CT performed 1 week later did not reveal any filling defect. At the time of discharge the patient was asymptomatic with no recurrence of thromboembolism on 6 months follow-up.
A 62-year-old woman was admitted to the hospital for acute ischaemia of the left hand evolving over 24 h. Six weeks previously she experienced subacute ischaemia of the right leg which spontaneously resolved. Doppler ultrasound of the left arm demonstrated an occlusion of the left brachial artery at its medial third, treated by embolectomy using a Fogarty catheter. The patient had no cardiovascular risk factors. She was normotensive and the heart was in normal sinus rhythm. Electrocardiogram, chest radiography and laboratory tests including coagulation (fibrinogen, prothrombin time, platelet count, bleeding time, dimer test, protein C, protein S, antithrombin III), and immunological studies (antinuclear and anticardiolipin antibodies, lupus anticoagulant) were normal. Two-dimensional echocardiography, performed on the second hospital day, showed normal cardiac contractility and no evidence of valvular disease or of thrombus in the cardiac cavities. Spiral CT of the aorta was performed on the third hospital day using a CT Twin Flash system (Elscint, Haifa, Israel) with collimation of 2 × 5 mm and a pitch of 1.5 (effective slice thickness: 5.5 mm). Enhanced images (150 ml of 25% iodinated contrast material at 4 ml/s) showed a large filling defect in the ascending aorta extending towards the aortic arch (Fig. 1a). Unenhanced CT images detected subtle irregularity of the left posterior wall of the ascending aorta with a calcified component indicative of atherosclerotic plaque (Fig. 1b). Transoesophageal echocardiography (TOE) and digital subtraction aortography (DSA) confirmed a pedunculated and highly mobile endoluminal aortic mass arising from the posterior wall of the ascending aorta (Fig. 1c). DSA was performed by pulmonary artery Author for correspondence and guarantor of study: Dr S. D. Qanadli, Service de Radiologie, Hoˆpital Ambroise Pare´, 9 avenue Charles de Gaulle, 92104 Boulogne Cedex, France.
DISCUSSION
Thrombus of the non-aneurysmal aorta is a known entity, previously reported to be a source of emboli producing arterial vascular occlusion of peripheral vessels, mesenteric, splenic or renal arteries [1,3,5–10,13–16]. Most of the reported aortic thrombi were located in the aortic arch [6–9], the descending thoracic aorta [10,13] and more frequently in the abdominal aorta from the tenth thoracic vertebra to the aortic bifurcation [1,3]. The ascending aorta is an uncommon location for IT.