- Email: [email protected]
Computed tomography of toxocara canis endophthalmitis
CT: THE JOURNAL
OF COMPUTED
TOMOGRAPHY
COMPUTED TOMOGRAPHY OF TOXOCARA ENDOPHTHALMITIS PHILIP A. TEMPLETON,
MD,
AND KRISHNA
Many lesions, termed pseudogliomas, may mimic the appearance of retinoblastoma, both clinically and on computed tomography. The appearance of Toxocara canis endophthalmitis on computed tomography is presented. The role of computed tomography in the evaluation of patients presenting with leukokoria is discussed.
1987;11:99-101
99
CAMS
C.V.G. RAO,
MD
CT studies have been described, including Coats’ disease (l), persistent hyperplastic primary vitreous (PHPV) (3), and more recently, infection due to Toxocara canis endophthalmitis (4). This report deals with the CT findings in a child presenting with leukokoria due to T. canis endophthalmitis. The CT features differed from those in previously described cases.
KEY WORDS:
Toxocara canis infection; Leukokoria; Retinoblastoma; Computed tomography
The role of computed tomography (CT) in the evaluation of orbital lesions, both intraocular and extraocular, is well established. Leukokoria (white or yellow-pink pupillary light reflex) (1) is a common clinical presentation in children suspected to have retinoblastoma, as well as certain other entities. In the evaluation of retinoblastoma, detecting a mass or calcification, as well as tumor involvement of the orbit, optic nerve, or intracranial extension, are the major roles of CT. The potential for clinical misdiagnosis of retinoblastoma has been found to exceed 50% (2). Several clinical entities, termed pseudogliomas (I), that may cause diagnostic confusion on
From the Department of Radiology, University of Maryland Medical System, Baltimore, Maryland; and the Department of Radiology, Prince George’s County General Hospital, Cheverly, Maryland. Address reprint requests to: Philip A. Templeton, MD, Department of Radiolow, University of Maryland Medical System, i2 South Greene St&& Baltimork, Maryland 21201. Received January 1986. 0 1987 by Elsevier Science Publishing Co., Inc. 52 Vanderbilt
Avenue,
0149-936X/87/$3.50
New
York,
NY
10017
CASE REPORT An 8-year-old boy presented with monocular leukokoria (white or yellow-pink pupillary light reflex) (2). A CT scan was obtained to exclude a diagnosis of retinoblastoma. The scan revealed a focal area of increased density in the vitreous body and microphthalmos unilaterally (Figure 1). There was slight enhancement following administration of intravenous contrast material (Figure 2). No calcifications were present, and the optic nerve and orbit were normal. No intracranial abnormalities were detected. The possibility that the mass represented a detached retina was entertained; however, exclusion of retinoblastoma was not possible. The enzyme-linked immunosorbent assay (ELISA) for Toxocara was positive at a titer of 1:8. At surgery the retina was detached and mangled in an inflammatory reaction and enucleation was necessary. Pathologic evaluation revealed nematode granuloma formation compatible with the diagnosis of T. canis endophthalmitis. DISCUSSION The CT appearance of sclerosing endophthalmitis due to T. canis infection has been reported by Hopper et al. (4). They have described a homogeneously dense vitreous without a discrete mass involving the entire posterior chamber. The diffuse homogeneous density on CT has been attributed to orga-
100
TEMPLETON
AND
RAO
CT: THE JOURNAL
OF COMPUTED
TOMOGRAPHY
VOL.
11 NO.
1
2. Sagittal reconstruction shows slight density enhancement following intravenous contrast infusion. FIGURE
nized vitreous, detached retina, and subretinal exudate (5). Our case presented the CT appearance of a discrete granuloma involving the detached retina, without homogeneous opacification of the vitreous body. Slight enhancement on the contrast mediumenhanced study did not help in differentiating an inflammatory mass from a neoplastic process. The potential for clinical misdiagnosis of retinoblastoma was found to exceed 50% in a study by Howard and Ellsworth (2). They reported on 500 patients with suspected retinoblastoma. In 265 of these patients, diagnoses other than retinoblastoma were ultimately made. Larval granulomatosis was determined to be the cause of leukokoria in 18 patients. Five had spotty calcification detected clinically. None of the patients in their series were studied with CT. Even with high-resolution CT of the
orbit, differentiation of other entities from retinoblastoma in a patient with leukokoria is difficult. The typical CT characteristics of retinoblastoma include a soft tissue mass involving the retina, which may be calcified. The lesion is bilateral in 25 to 33% of cases. Thickening of the optic nerve and tumor involvement of the intracranial subarachnoid space in contrast medium-enhanced CT are evidence for tumor extension (6). Other entities in the differential diagnosis whenever CT findings have been presented included PHPV and Coats’ disease. In PHPV the embryonic hyaloid vascular system does not regress, and the patient presents with unilateral or bilateral leukokoria. Mafee et al. (3) reported on five patients with PHPV. Their CT findings included soft tissue of increased density replacing the vitreous body, microphthalmos, re-
JANUARY 1987
trohyaloid layered blood, hypervascularity of the vitreous, and lack of intraocular calcification. Coats’ disease is a vascular anomaly of the retina with telangiectatic vessels that leak serum and lipid in the retina and subretinal space. Sherman et al. (1) described two cases of Coats’ disease with CT findings. Both cases demonstrated increased density in the vitreous, normal-sized globes, no abnormal calcification, and otherwise normal orbits. Toxocara canis, the dog roundworm, has two forms of clinical expression: visceral and ocular (5). Following ingestion of eggs of Toxocara, a larva can migrate to the eye, where it dies, producing an inflammatory granulomatous reaction causing opacification of the vitreous and retinal detachment. This occurs in young children in close contact with dogs, usually puppies (1). In most cases the anterior segment is uninvolved (7). Retinal, subretinal, and vitreous hemorrhages are common (7). Diagnosis is aided by the ELISA test for Toxocara, although some cases of infection with negative titers have been reported (8). Therapeutic measures have included topical and oral corticosteroids, antihelmintics, laser photocoagulation, and pars plana vitrectomy (9). Currently CT diagnosis of the various lesions causing leukokoria remains unsatisfactory. The scan is helpful if a lesion clearly fits the diagnosis of retinoblastoma. Even lack of calcification is not helpful, as occasionally retinoblastomas do not calcify (4). The CT appearances described for Coats’ disease, PHPV, and T. canis endophthalmitis do not seem to be pathognomonic. Clinical correlation may improve diagnostic accuracy. Further characterization of the disease processes may make CT more discriminating in the future, and magnetic resonance imaging may have a role.
3. Mafee.M, Godberg M, Valvassori G, et al.: Computed tomograp&:-in the evaluation of patients with persistent hyperplastic primary vitreous (PHPV). Radiology 1982;145:713. 4. Hopper KD, Katz NN, Dorwart RH, et al.: Childhood leukokoria: computed tomographic appearance and differential diagnosis with histopathologic correlation. Radiographics 1985;5:377. 5. Zinkham W: Visceral larva migrams: A review and reassessment indicating two forms of clinical expressions: visceral and ocular. Am J Dis Child 1978;132:627. 6. Rao K, Lee S: Cranial computed tomography. New York: McGraw-Hill, 1983:92-3. 7. Margo C, Katz N, Wertz F, et al.: Sclerosing endophthalmitis in children: computed tomography with histopathologic correlation. J Pediatr Ophthalmol 1983;20:180. 8. Kielar R: Toxocara canis endophthalmitis with low ELISA titer. Ann Ophthalmol 1983;15:447. 9. Belmont J, Irvine A, Benson W, et al.: Vitrectomy in ocular toxocariasis. Arch Ophthalmol 1982;100:1912.
CONTINUING
MEDICAL
EDUCATION
QUESTIONS
1. The clinical finding of leukokoria refers to:
a. b. c. d.
White or yellow-pink papillary light reflex. White blood cells in tears. Plaques on the lens of the eye. Low white blood cell count.
2. Retinoblastoma
presents
as a bilateral
lesion
in:
a. Less than 1% of cases. b. 10% of cases. c. 25 to 33% of cases. d. 50% of cases. 3. The
plastic
following primary
are true concerning vitreous except:
persistent
hyper-
a. The embryonic hyaloid vascular system does not regress. b. It always presents with bilateral leukokoria. c. It may cause microphthalmos. d. No intraocular calcification is found. 4.
REFERENCES
101
TOXOCARA CANIS ENDOPHTHALMITIS
The following are true concerning TOXOCQ~Q canis except: a. It has two forms of clinical expression, visceral and ocular.
1. Sherman JL, McLean IW, Brallier DR: Coat’s disease: CTpathologic correlation in two cases. Radiology 1983;146:77.
b. The ELISA test is a diagnostic aid.
2. Howard GM, Ellsworth RM: Differential diagnosis of retinoblastoma. A statistical survey of 500 children. Relative frequency of lesions which simulate retinoblastoma. Am J Ophthalmol 1965;60:610.
C. It usually occurs in adults. d. Retinal, subretinal, and vitreous hemorrhages are common.
OF COMPUTED
TOMOGRAPHY
COMPUTED TOMOGRAPHY OF TOXOCARA ENDOPHTHALMITIS PHILIP A. TEMPLETON,
MD,
AND KRISHNA
Many lesions, termed pseudogliomas, may mimic the appearance of retinoblastoma, both clinically and on computed tomography. The appearance of Toxocara canis endophthalmitis on computed tomography is presented. The role of computed tomography in the evaluation of patients presenting with leukokoria is discussed.
1987;11:99-101
99
CAMS
C.V.G. RAO,
MD
CT studies have been described, including Coats’ disease (l), persistent hyperplastic primary vitreous (PHPV) (3), and more recently, infection due to Toxocara canis endophthalmitis (4). This report deals with the CT findings in a child presenting with leukokoria due to T. canis endophthalmitis. The CT features differed from those in previously described cases.
KEY WORDS:
Toxocara canis infection; Leukokoria; Retinoblastoma; Computed tomography
The role of computed tomography (CT) in the evaluation of orbital lesions, both intraocular and extraocular, is well established. Leukokoria (white or yellow-pink pupillary light reflex) (1) is a common clinical presentation in children suspected to have retinoblastoma, as well as certain other entities. In the evaluation of retinoblastoma, detecting a mass or calcification, as well as tumor involvement of the orbit, optic nerve, or intracranial extension, are the major roles of CT. The potential for clinical misdiagnosis of retinoblastoma has been found to exceed 50% (2). Several clinical entities, termed pseudogliomas (I), that may cause diagnostic confusion on
From the Department of Radiology, University of Maryland Medical System, Baltimore, Maryland; and the Department of Radiology, Prince George’s County General Hospital, Cheverly, Maryland. Address reprint requests to: Philip A. Templeton, MD, Department of Radiolow, University of Maryland Medical System, i2 South Greene St&& Baltimork, Maryland 21201. Received January 1986. 0 1987 by Elsevier Science Publishing Co., Inc. 52 Vanderbilt
Avenue,
0149-936X/87/$3.50
New
York,
NY
10017
CASE REPORT An 8-year-old boy presented with monocular leukokoria (white or yellow-pink pupillary light reflex) (2). A CT scan was obtained to exclude a diagnosis of retinoblastoma. The scan revealed a focal area of increased density in the vitreous body and microphthalmos unilaterally (Figure 1). There was slight enhancement following administration of intravenous contrast material (Figure 2). No calcifications were present, and the optic nerve and orbit were normal. No intracranial abnormalities were detected. The possibility that the mass represented a detached retina was entertained; however, exclusion of retinoblastoma was not possible. The enzyme-linked immunosorbent assay (ELISA) for Toxocara was positive at a titer of 1:8. At surgery the retina was detached and mangled in an inflammatory reaction and enucleation was necessary. Pathologic evaluation revealed nematode granuloma formation compatible with the diagnosis of T. canis endophthalmitis. DISCUSSION The CT appearance of sclerosing endophthalmitis due to T. canis infection has been reported by Hopper et al. (4). They have described a homogeneously dense vitreous without a discrete mass involving the entire posterior chamber. The diffuse homogeneous density on CT has been attributed to orga-
100
TEMPLETON
AND
RAO
CT: THE JOURNAL
OF COMPUTED
TOMOGRAPHY
VOL.
11 NO.
1
2. Sagittal reconstruction shows slight density enhancement following intravenous contrast infusion. FIGURE
nized vitreous, detached retina, and subretinal exudate (5). Our case presented the CT appearance of a discrete granuloma involving the detached retina, without homogeneous opacification of the vitreous body. Slight enhancement on the contrast mediumenhanced study did not help in differentiating an inflammatory mass from a neoplastic process. The potential for clinical misdiagnosis of retinoblastoma was found to exceed 50% in a study by Howard and Ellsworth (2). They reported on 500 patients with suspected retinoblastoma. In 265 of these patients, diagnoses other than retinoblastoma were ultimately made. Larval granulomatosis was determined to be the cause of leukokoria in 18 patients. Five had spotty calcification detected clinically. None of the patients in their series were studied with CT. Even with high-resolution CT of the
orbit, differentiation of other entities from retinoblastoma in a patient with leukokoria is difficult. The typical CT characteristics of retinoblastoma include a soft tissue mass involving the retina, which may be calcified. The lesion is bilateral in 25 to 33% of cases. Thickening of the optic nerve and tumor involvement of the intracranial subarachnoid space in contrast medium-enhanced CT are evidence for tumor extension (6). Other entities in the differential diagnosis whenever CT findings have been presented included PHPV and Coats’ disease. In PHPV the embryonic hyaloid vascular system does not regress, and the patient presents with unilateral or bilateral leukokoria. Mafee et al. (3) reported on five patients with PHPV. Their CT findings included soft tissue of increased density replacing the vitreous body, microphthalmos, re-
JANUARY 1987
trohyaloid layered blood, hypervascularity of the vitreous, and lack of intraocular calcification. Coats’ disease is a vascular anomaly of the retina with telangiectatic vessels that leak serum and lipid in the retina and subretinal space. Sherman et al. (1) described two cases of Coats’ disease with CT findings. Both cases demonstrated increased density in the vitreous, normal-sized globes, no abnormal calcification, and otherwise normal orbits. Toxocara canis, the dog roundworm, has two forms of clinical expression: visceral and ocular (5). Following ingestion of eggs of Toxocara, a larva can migrate to the eye, where it dies, producing an inflammatory granulomatous reaction causing opacification of the vitreous and retinal detachment. This occurs in young children in close contact with dogs, usually puppies (1). In most cases the anterior segment is uninvolved (7). Retinal, subretinal, and vitreous hemorrhages are common (7). Diagnosis is aided by the ELISA test for Toxocara, although some cases of infection with negative titers have been reported (8). Therapeutic measures have included topical and oral corticosteroids, antihelmintics, laser photocoagulation, and pars plana vitrectomy (9). Currently CT diagnosis of the various lesions causing leukokoria remains unsatisfactory. The scan is helpful if a lesion clearly fits the diagnosis of retinoblastoma. Even lack of calcification is not helpful, as occasionally retinoblastomas do not calcify (4). The CT appearances described for Coats’ disease, PHPV, and T. canis endophthalmitis do not seem to be pathognomonic. Clinical correlation may improve diagnostic accuracy. Further characterization of the disease processes may make CT more discriminating in the future, and magnetic resonance imaging may have a role.
3. Mafee.M, Godberg M, Valvassori G, et al.: Computed tomograp&:-in the evaluation of patients with persistent hyperplastic primary vitreous (PHPV). Radiology 1982;145:713. 4. Hopper KD, Katz NN, Dorwart RH, et al.: Childhood leukokoria: computed tomographic appearance and differential diagnosis with histopathologic correlation. Radiographics 1985;5:377. 5. Zinkham W: Visceral larva migrams: A review and reassessment indicating two forms of clinical expressions: visceral and ocular. Am J Dis Child 1978;132:627. 6. Rao K, Lee S: Cranial computed tomography. New York: McGraw-Hill, 1983:92-3. 7. Margo C, Katz N, Wertz F, et al.: Sclerosing endophthalmitis in children: computed tomography with histopathologic correlation. J Pediatr Ophthalmol 1983;20:180. 8. Kielar R: Toxocara canis endophthalmitis with low ELISA titer. Ann Ophthalmol 1983;15:447. 9. Belmont J, Irvine A, Benson W, et al.: Vitrectomy in ocular toxocariasis. Arch Ophthalmol 1982;100:1912.
CONTINUING
MEDICAL
EDUCATION
QUESTIONS
1. The clinical finding of leukokoria refers to:
a. b. c. d.
White or yellow-pink papillary light reflex. White blood cells in tears. Plaques on the lens of the eye. Low white blood cell count.
2. Retinoblastoma
presents
as a bilateral
lesion
in:
a. Less than 1% of cases. b. 10% of cases. c. 25 to 33% of cases. d. 50% of cases. 3. The
plastic
following primary
are true concerning vitreous except:
persistent
hyper-
a. The embryonic hyaloid vascular system does not regress. b. It always presents with bilateral leukokoria. c. It may cause microphthalmos. d. No intraocular calcification is found. 4.
REFERENCES
101
TOXOCARA CANIS ENDOPHTHALMITIS
The following are true concerning TOXOCQ~Q canis except: a. It has two forms of clinical expression, visceral and ocular.
1. Sherman JL, McLean IW, Brallier DR: Coat’s disease: CTpathologic correlation in two cases. Radiology 1983;146:77.
b. The ELISA test is a diagnostic aid.
2. Howard GM, Ellsworth RM: Differential diagnosis of retinoblastoma. A statistical survey of 500 children. Relative frequency of lesions which simulate retinoblastoma. Am J Ophthalmol 1965;60:610.
C. It usually occurs in adults. d. Retinal, subretinal, and vitreous hemorrhages are common.