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Table of Contents    
Year : 2018  |  Volume : 66  |  Issue : 1  |  Page : 255-256

Dirofilariasis mimicking an osteoma

1 Department of Neurosurgery, St. Gregorius Medical Mission Hospital, Parumala, India
2 Department of Pahology, Metro Scans, Trivandrum, Kerala, India

Date of Web Publication11-Jan-2018

Correspondence Address:
Roshith H Chekkattu
Department of Neurosurgery, St. Gregorius Medical Mission Hospital, Parumala P.O., Thiruvalla, Pathanamthitta, Kerala - 689 626
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.222868

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How to cite this article:
Sreekumar M, Goethe J, Chekkattu RH. Dirofilariasis mimicking an osteoma. Neurol India 2018;66:255-6

How to cite this URL:
Sreekumar M, Goethe J, Chekkattu RH. Dirofilariasis mimicking an osteoma. Neurol India [serial online] 2018 [cited 2020 Mar 29];66:255-6. Available from:


Dirofilaria can be broadly classified into three types – Dirofilaria immitis, D. repens, and D. tenuis. D. immitis affects humans under very rare circumstances. D. tenuis, though some cases have been reported, is also rare in humans. Humans are the accidental hosts of D. repens; when an infected mosquito takes a blood meal, it injects larva into human blood.[1],[2],[3],[4]

We report the case of a 44-year old female subject who presented with a single subcutaneous swelling on the right temporal scalp of a week's duration. On examination, the swelling was not painful, non-mobile, and moderate-to-hard in consistency. No increase in size was noted in 1 week. There was no history of fever. Clinical features were suggestive of an osteoma, and the excision of the same was planned.

The patient underwent excision of the swelling. On excision of the subcutaneous layer and resection of the base, multiple, live filament-like worms were extracted from the swelling. Specimens were collected and sent for histopathological examination. Wound closure was done after debridement and cleaning.

Both the filamentous worms and the abscess capsule were sent for histopathological examination. Microscopically, the sample revealed adult nematode parasites [Figure 1], [Figure 2], [Figure 3]; and, the skeletal muscle showed a cavity lined by granulation tissue having dense macrophages, mixed inflammatory cell infiltration, along with reactive changes of skeletal muscle [Figure 2]. Findings were suggestive of dirofilariasis with abscess formation.
Figure 1: Dirofilaria microscopic view

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Figure 2: The abscess cavity surrounding Dirofilaria repens infestation

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Figure 3: Dirofilaria through the pathologist's eye

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Dirofilariasis is a parasitic infection caused by the genus Dirofilaria. Though different subtypes of dirofilariasis have been recognized, the main species which causes human infections are D. immitis, D. repens, and D. tenuis. Among these, the most commonly reported cases are of D. repens. Epidemiologically, D. repens are confined mainly to eastern Europe, central Asia, and Sri Lanka. In India, the southern states of India are more susceptible to Dirofilaria infections as these are geographically close to Sri Lanka. Cases reported among Asian population mostly present as subcutaneous nodules, although they can present as lung parenchymal disease. Humans are the accidental hosts; infection is spread by mosquito bites when the infective larvae are injected into the human body. However, human-to-human transmission is not possible as the transmission of dirofilariasis occurs through microfilaria. D. repens typically manifests as subcutaneous nodules on the face, beneath the eyes, on the extremities, and sometimes on the genitals.[5],[6]

Diagnosis is usually made retrospectively as most cases are confirmed as Dirofilaria infection on excision of the subcutaneous nodules where live filamentous parasites are found; the species is confirmed later by histopathological examination. The ideal treatment modality is excision of nodules, followed by administration of antifilarial medications for a brief period. Complications are rare and recurrence is usually not seen. Follow-up is usually not required. No fatality has been reported so far.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Perera J, Martinez R, Bravio G. Current directions in the immunodiagnosis of human dirofilariasis. Trop Med Parasitol 1994;45:249-52.  Back to cited text no. 1
Joseph E. Mathai A, Abraham LK, Thomas S. Subcutaneous human dirofilariasis. J Parasit Dis 2011;35:140-3.  Back to cited text no. 2
Faust EC, Thomas ER, Jone J. Discovery of human heartworm infection in New Orleans. J Parasitol 1941;27:115-22.  Back to cited text no. 3
Pampiglione S, Canestri Trotti G, Rivasi, F. Human dirofilariasis due to dirofilaria repens; A review of the world literature. Parasitologia 1995;37:149-93.  Back to cited text no. 4
Bhat KG, Wilson G, Mallya S. Human dirofilariasis. Indian J Microbiol 2003;21:65.  Back to cited text no. 5
Sabu L, Devada K, Subramaniam H. Dirofilariasis in dogs and humans in Kerala. Indian J Med Res 2005;121:691-3.  Back to cited text no. 6


  [Figure 1], [Figure 2], [Figure 3]


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