1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [5f5779ef-8052-43d8-b819-61268a250b08] => Array
        (
            [runtime-id] => 5f5779ef-8052-43d8-b819-61268a250b08
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [0ed856c9-9654-477f-8a76-ed1d2eab3534] => Array
                        (
                            [runtime-id] => 0ed856c9-9654-477f-8a76-ed1d2eab3534
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [35dbedc0-918f-4da0-9d2f-cd61926cfa85] => Array
        (
            [runtime-id] => 35dbedc0-918f-4da0-9d2f-cd61926cfa85
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [7f0a06c2-d9f5-496c-80a8-1982e5c8ccd2] => Array
                        (
                            [runtime-id] => 7f0a06c2-d9f5-496c-80a8-1982e5c8ccd2
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [41fc3433-230c-4e9a-8c15-6423d1d613bf] => Array
        (
            [runtime-id] => 41fc3433-230c-4e9a-8c15-6423d1d613bf
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [23d2da26-51d7-4282-ab8a-51db494fbe91] => Array
                        (
                            [runtime-id] => 23d2da26-51d7-4282-ab8a-51db494fbe91
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [9a70dda2-c7c4-4578-8805-61b4fa563482] => Array
        (
            [runtime-id] => 9a70dda2-c7c4-4578-8805-61b4fa563482
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [39d9c30a-e8b3-4e2d-870b-f0f5a6c9b389] => Array
                        (
                            [runtime-id] => 39d9c30a-e8b3-4e2d-870b-f0f5a6c9b389
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [9a70dda2-c7c4-4578-8805-61b4fa563482] => Array
        (
            [runtime-id] => 9a70dda2-c7c4-4578-8805-61b4fa563482
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [39d9c30a-e8b3-4e2d-870b-f0f5a6c9b389] => Array
                        (
                            [runtime-id] => 39d9c30a-e8b3-4e2d-870b-f0f5a6c9b389
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [5f5779ef-8052-43d8-b819-61268a250b08] => Array
        (
            [runtime-id] => 5f5779ef-8052-43d8-b819-61268a250b08
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [0ed856c9-9654-477f-8a76-ed1d2eab3534] => Array
                        (
                            [runtime-id] => 0ed856c9-9654-477f-8a76-ed1d2eab3534
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [5f5779ef-8052-43d8-b819-61268a250b08] => Array
        (
            [runtime-id] => 5f5779ef-8052-43d8-b819-61268a250b08
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [0ed856c9-9654-477f-8a76-ed1d2eab3534] => Array
                        (
                            [runtime-id] => 0ed856c9-9654-477f-8a76-ed1d2eab3534
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [5f5779ef-8052-43d8-b819-61268a250b08] => Array
        (
            [runtime-id] => 5f5779ef-8052-43d8-b819-61268a250b08
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [0ed856c9-9654-477f-8a76-ed1d2eab3534] => Array
                        (
                            [runtime-id] => 0ed856c9-9654-477f-8a76-ed1d2eab3534
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [5f5779ef-8052-43d8-b819-61268a250b08] => Array
        (
            [runtime-id] => 5f5779ef-8052-43d8-b819-61268a250b08
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [0ed856c9-9654-477f-8a76-ed1d2eab3534] => Array
                        (
                            [runtime-id] => 0ed856c9-9654-477f-8a76-ed1d2eab3534
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)
1naresh2naresh
Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

    [58e0d380-6626-4e6d-949c-76e76be05894] => Array
        (
            [runtime-id] => 58e0d380-6626-4e6d-949c-76e76be05894
            [type] => toll-free-key
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [332ca1a5-b661-4150-93cd-0eb3bb2a6636] => Array
                        (
                            [runtime-id] => 332ca1a5-b661-4150-93cd-0eb3bb2a6636
                            [type] => toll-free-key
                        )

                )

            [credentials] => Array
                (
                    [method] => toll-free-key
                    [value] => tf_ipsecsha;8f140109f33e2c5c0972aa6a0cc2c6061387756e
                )

        )

)


  
    








































































    Orbital Dirofilariasis: MR Findings | American Journal of Neuroradiology  
    



















    































    
  
  




    
    

  

      


    

      

  
  
  

    

  

    

  

                
    

      

  

    

  
      
  
  

    


Advertisement



  



  


  
  



  



    

  


  


  


  
  
  
  
  
  

  	      


    
      

    
  
    
        
    

  

    
                        

  

                
    

      

	  

		
		

			

			  

  
      
  
  

    

  
  
      
Research ArticleHEAD AND NECK

  
      

  
      
Orbital Dirofilariasis: MR Findings
  
    	
Reinhard Groell, Gerhard Ranner, Martin M. Uggowitzer and Hannes Braun

  
    	
American Journal of Neuroradiology February 1999,  20 (2) 285-286; 

  
  
  



  


  
  



			

		

	
	
 	
	  
  

		
		

			

			  

  
      
  
  

    
  


  
  



  
      
  
  

    

  

    

  
      
  
  

    
Abstract
Summary: Dirofilariasis is a helminthic zoonosis occurring in many parts of the world. We report the findings in a 61-year-old woman who had painless right exophthalmos caused by orbital dirofilariasis. A vivid worm was embedded inside an inflammatory nodule in the right orbit. On T1-weighted MR images, the parasite was visible as a discrete, low-intensity, tubular signal in the center of the nodule surrounded by contrast-enhancing inflammatory tissue.
Dirofilariasis is a worldwide helminthic zoonosis. The species Dirofilaria repens is endemic in southern-middle Europe and in some parts of Asia and Africa (1). Dogs are the primary hosts of this parasite, humans are rarely affected. We report the case of a 61-year-old woman with orbital dirofilariasis and describe the MR imaging findings.
Case Report
A 61-year-old woman had a 6-month history of progressive painless exophthalmos of her right orbit. On MR examination, a 2.5-cm mass was visible in the right lower-medial retrobulbar part of the orbit, adjacent to the medial orbital wall. The center of the lesion showed high signal on T2-weighted images (Fig 1A). On T1-weighted images, the center of the lesion had a discrete tubular structure of low signal intensity within it (Fig 1B). The lesion was surrounded by a 3-mm-thick capsular structure with low signal intensity on T1- and T2-weighted images. After intravenous administration of contrast material, this capsule and parts of the contents of the lesion showed marked contrast enhancement, except for the above-mentioned central low-signal tubular structure (Fig 1C). These MR findings led us to suspect an inflammatory pseudotumor.
fig 1.
fig 1. 
61-year-old woman with human dirofilariasis. 
A, Axial T2-weighted MR image (1800/90 [TR/TE]) shows an encapsulated lesion (arrow) of central high signal intensity in the medial right orbit.
B, A tubular central structure (arrow) of intermediate signal intensity is visible within the lesion on sagittal T1-weighted image (452/25).
C, After intravenous administration of contrast material, the capsule and the surroundings of the central tubular structure (arrow) show a marked enhancement on T1-weighted image (452/25).
D, Photograph of the worm (Dirofilaria repens, length, 12 cm; diameter, 0.3–0.5 mm) after it was removed from the capsule.
The patient reported having made several trips to Italy and Greece within the preceding 5 years; however, all relevant laboratory findings were negative (eg, eosinophilic granulocytes; parasitologic testing for helminths in urine, feces, and sputum; and serum enzyme-linked immunosorbent assay (ELISA) screening for filarial antigen).
The lesion was resected, and a live, moving worm (length, 12 cm; diameter, 0.3–0.5 mm) appeared in its center (Fig 1D). The worm was classified as D. repens. The lesion capsule consisted of unspecified granulomatous and fibrous tissue. The center of the lesion contained granulomatous tissue and putrid liquid that, upon culture, proved to contain Streptococci viridans and Propionibacterium acnes. The exophthalmos resolved, and no further treatment was necessary.
Discussion
Dirofilariasis is a worldwide helminthic zoonosis. The species most relevant to humans are D. immitis, D. tenius, D. ursi, and D. repens. Dirofilaria (Nochtiella) repens is endemic in southern-middle Europe and in some parts of Asia and Africa. Approximately 400 cases of human dirofilariasis due to D. repens have been reported in the literature (1). The imaging features of dirofilariasis are not well known, and, to our knowledge, MR findings have not been described.
Dirofilaria is a common parasite of dogs, which constitute the main source of infection. Adult worms reside in the right side of the heart and the pulmonary vessels of the dog, where they produce larvae (microfilariae). The larvae circulate in the blood and may be ingested by mosquitos, which serve as vectors, infecting other dogs. Once the larvae have penetrated the final host, they develop into adult worms within 6 months (2, 3).
Humans are infected only accidentally, and many are asymptomatic. In humans, the nematode causes a subcutaneous or superficially located inflammatory reaction, trapping it within a nodule, where it may survive for many years (3–5). Occasionally, the nematode may invade the vascular system and lead to visceral, mainly pulmonary, forms of dirofilariasis. On chest radiographs and CT scans, these pulmonary manifestations have been described as sharply defined lesions in the periphery of the lungs, resembling neoplasms (“coin lesions”) (6, 7). In addition to the lungs, dirofilariae have been detected in the heart and in the abdomen (4). This visceral dirofilariasis has to be distinguished from the visceral manifestation of toxocariasis (a parasitosis caused by Toxocara species) also known as visceral larva migrans.
In humans, the worm cannot reach maturity and is therefore unable to express larvae into the blood system, which is why serologic results are of little value. Only occasionally patients may have moderate eosinophilia (3). In the reported case, all relevant tests were negative, however.
In general, the diagnosis of human dirofilariasis is based on histologic examination. Therapy with systemic antibiotics has proved useless, and surgical removal of the worm is the only known treatment. Usually, the clinical symptoms disappear after the parasite is removed, and no adjunct therapy is necessary.
In our patient, the parasite caused a painless inflammatory retrobulbar nodule, leading to exophthalmos. Among other neoplastic, granulomatous, or inflammatory diseases, the differential diagnosis includes other parasitoses with potential orbital manifestations, such as cysticercosis, hydatid cyst, and onchocerciasis. As in most other cases of human dirofilariasis, the exact time and location of infection could not be determined in our patient. Because the parasite maturates within 6 months, it is likely that she was infected during one of her journeys to southern Europe.
Conclusion
On MR examinations of our patient with dirofilariasis, the inflammatory nodule embedding the parasite appeared as a thick-walled semiliquid structure on T2-weighted images. On T1-weighted images, the lesion showed a discrete, tubular, central signal, which obviously represented the worm. The tissue surrounding the tubular structure, as well as the capsule, showed considerable enhancement after contrast administration, consistent with a reactive inflammatory process. The parasite, which appeared as a tubular pattern of low signal intensity on T1-weighted images, could not be delineated on proton density–and T2-weighted sequences.
Footnotes
  • ↵1 Address reprint requests to Reinhard Groell, MD, Department of Radiology, University Hospital Graz, Auenbruggerplatz 9, A-8036, Graz, Austria.
References
  1. ↵
    Pampiglione S, Canestri-Trotti G, Rivasi F.   Human dirofilariasis due to Dirofilaria (Nochtiella) repens: a review of the world literature.  Parassitologia  1995;37:149-193
    PubMed
  2. ↵
    Webber WAF, Hawking F.   Experimental maintenance of Dirofilaria repens and D. immitis in dogs.  Exp Parasitol  1955;4:143-146
    PubMed
  3. ↵
    Garcia LS, Bruckner DA.  Diagnostic Medical Parasitology  Washington, DC: American Society for Microbiology;   1993;237-265
  4. ↵
    Tsieh S.  Diagnostic Parasitology  Tokyo: Igaku-Shoin Medical Publishers;   1988;211-213
  5. Gardiner CH, Oberdorfer CE, Reyes JE, Pinkus WH.   Infection of man by Dirofilaria repens.  Am J Trop Med Hyg  1978;27:1279-1281
  6. ↵
    Milanez de Compos JR, Barbas CS, Filomeno LT,   et al.   Human pulmonary dirofilariasis: analysis of 24 cases from Sao Paulo.  Chest  1997;112:729-733
    CrossRefPubMed
  7. Pampiglione S, Del Maschio O, Pagan V, Rivasi F.   Pulmonary dirofilariasis in man: a new Italian case.  Parasite  1994;1:379-385
    PubMed
  • Received April 17, 1998.
View Abstract
  


  
  



  
      
  
  

    
  


  
  



  




  


  
  



  
      
  
  

    
  


  
  



  
      
  
  

     Back to top  


  
  



			

		

		
		

			

			  

  
        
In this issue

    
  
  

    
  


  
  



  
      
  
  

    

  

    

  
      
  
  

    


Advertisement



  



  


  
  



  



  


  
  



  
      
  
  

    

	  
  

		

          

            

  
      
  
  

     Print  


  
  



  
      
  
  

     Download PDF  


  
  



  
      
  
  

    
 Email Article
  


  
  



  
      
  
  

    
 Citation Tools
  


  
  



          

        

        
        

          

            



  
      
  
  

    

  

    

  
      
  
  

    

  
  
  
  
      
Orbital Dirofilariasis: MR Findings
  
    	
Reinhard Groell, Gerhard Ranner, Martin M. Uggowitzer, Hannes Braun

  
    	
American Journal of Neuroradiology Feb 1999, 20 (2) 285-286; 

  
  
  



  


  
  



  
      
  
  

    

  
    
  
  
    
  
  
    
  


  


  
  



  
      
  
  

    
del.icio.us logo Twitter logo Facebook logo Mendeley logo
  


  
  



  



  


  
  



  
      
  
  

    
  


  
  



          

        

	
 	
	
	


  


  
  



  
        
Jump to section

    
  
  

    
  


  
  



  
      
  
  

    

  

    
 Related Articles
  • No related articles found.
 Cited By...
 More in this TOC Section
 Similar Articles

  



  


  
  



			

		

	
	
 	
	
	


    

  



  

                
    

      

  

    

  
      
  
  

    


Advertisement