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Year : 2019  |  Volume : 12  |  Issue : 6  |  Page : 550-552  

Dirofilariasis mimicking as a breast tumor: A report of two cases

1 Department of Pathology, K S Hegde Medical Academy, Nitte University, Mangalore, Karnataka, India
2 Department of Surgery, K S Hegde Medical Academy, Nitte University, Mangalore, Karnataka, India

Date of Submission24-Nov-2018
Date of Acceptance29-Mar-2019
Date of Web Publication17-Oct-2019

Correspondence Address:
H L Kishan Prasad
Department of Pathology, K S Hegde Medical Academy, Nitte University, Mangalore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjdrdypu.mjdrdypu_239_18

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Dirofilariasis is a zoonotic filarial parasitic infestation. Its prevalence has increased in recent times. Hence, it is described as an emerging zoonosis. However, not many cases of subcutaneous manifestation of the disease have been reported in the literature. Here, we are presenting two cases of dirofilariasis manifesting as a breast mass causing a diagnostic dilemma in treating clinician. We present two cases of dirofilariasis in the breast tissue mimicking a tumor initially, and on histopathology, it was diagnosed as a Dirofilaria infestation. The increased incidence of Dirofilaria infestation in the Southern part of the country has created a need for increased awareness among the population living in endemic areas to reduce the load of the parasite. Hence it is an ideal time to initiate the primary preventive measures to reduce the incidence of Dirofilaria infestation.

Keywords: Breast tumor, dirofilariasis, histopathology, ivermectin, zoonosis

How to cite this article:
Kishan Prasad H L, Rao C, Lobo L, Chakravarthy A, Prabhu S, Shetty K J. Dirofilariasis mimicking as a breast tumor: A report of two cases. Med J DY Patil Vidyapeeth 2019;12:550-2

How to cite this URL:
Kishan Prasad H L, Rao C, Lobo L, Chakravarthy A, Prabhu S, Shetty K J. Dirofilariasis mimicking as a breast tumor: A report of two cases. Med J DY Patil Vidyapeeth [serial online] 2019 [cited 2022 Aug 20];12:550-2. Available from: https://www.mjdrdypv.org/text.asp?2019/12/6/550/269424

  Introduction Top

Human dirofilariasis is caused by the nematode belonging to the genus Dirofilaria.[1],[2],[3] They are natural parasites found in cats, foxes, dogs, and wild animals.[2] It is a mosquito-borne infestation caused by Culex, Aedes, and Anopheles species.[4],[5] There are forty isolated species of dirofilariasis, of which six species are known to cause human infection.[5],[6] Majority of the cases in India are an ocular Dirofilaria infestation.[2] However, there are few case reports of dirofilariasis with subcutaneous manifestations. We present two cases of subcutaneous dirofilariasis affecting the breast manifesting as a breast mass.

  Case Reports Top

Case 1

A 52-year-old female, from Northern part of Kerala, presented with a lump in the right breast measuring 1.5 cm × 1.5 cm near the axillary tail. A mammogram revealed a small oval dense lesion in the right upper outer quadrant of the right breast in the premammary region with fluid collection in the center. Fine-needle aspiration cytology from the lump showed granulomatous changes with acute mastitis. Complete hemogram was normal. Excision biopsy of the lump showed on gross measuring 3 cm × 2 cm with gray-white to the gray-brown cut surface. Some areas showed mucoid material. Microscopically, a nematode (worm) with multilayered cuticle was seen [Figure 1]. The outermost layer showed wavy longitudinal ridges with few transverse striations and muscle layer just below the cuticle [Figure 2] shown with arrows]. The surrounding tissue showed a granulomatous response with mixed inflammatory cells comprising lymphocytes, neutrophils, eosinophils, and plasma cells. The final diagnosis of Dirofilaria repens infestation was made. Peripheral smear showed no evidence of microfilaraemia. The patient was started on ivermectin and doxycycline therapy. The patient has tolerated the procedure well and is on regular follow-up for 2 years without any fresh lesions.
Figure 1: Histopathology of the breast mass showing multiple sections of nematode (worm) with multilayered cuticle (H and E, ×40)

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Figure 2: Histopathology showing the outermost layer with wavy longitudinal ridges and few transverse striations with the muscle layer just below the cuticle shown with arrows (H and E, ×100)

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Case 2

A 50-year-old female, hailing from the coastal region in South India, presented with a lump measuring 4 cm × 3.5 cm in the upper outer quadrant of the right breast for 2 months. It was freely mobile and firm in consistency, not associated with pain. On examination, no lymph nodes were palpable in the axilla. Differential blood count showed evidence of eosinophilia, with absolute eosinophil count of 0.1 × 109/L. Biochemical and serological parameters were within normal limits. Clinically, the lesion was considered as a fibroadenoma. The lump was excised, and histopathology showed the same morphology as described in Case 1 confirming D. repens [Figure 3] shown with arrows with fragments of filarial wall with foreign body giant cell reaction]. Peripheral smear showed no evidence of microfilaraemia. She is under regular follow-up without any fresh complaints.
Figure 3: Histopathology of the Case 2 with filarial wall fragments with foreign body giant cell reaction (H and E, ×100)

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  Discussion Top

Dirofilariasis is an arthropod-borne infestation, the incidence of which is rising due to varied climatic conditions, global warming, animal host population, and vector breeding.[1]

Francesco Birago, an Italian by origin, was the first person who has described Dirofilaria worm in 1626.[1]D. repens was first published by Angelo Pace at Palermo in 1867.[6] Magalhaes, from Brazil, in 1887 first published a case report of subcutaneous infestation in a male child,[1],[7] and the first case affecting a female was published in 1945 at New Orleans.[1] Human ocular dirofilariasis caused by D. repens was first reported in 1965 at France.[1],[8] In India, the first case report was published in the year 1989.[5]

Dirofilariasis is an uncommon parasitic infestation caused by filarial nematodes.[5] Literature quotes six species of Dirofilaria causing human infection.[2],[5] They include D. repens, Dirofilaria immitis, Dirofilaria tenius, Dirofilaria striata, Dirofilaria Spectans, and Dirofilaria ursi.[1],[2],[3] Subcutaneous filariasis is mostly caused by D. repens, D. striata, D. tenius, and D. ursi.[3],[6]

Dirofilariasis is an endemic disease in South India, with very few confirmed cases from Western and Northern India.[1],[2] Kerala is considered highly endemic due to varied climatic conditions and presence of vectors.[2]D. repens is the most prevalent in Asia, Sri Lanka Eastern, and Southern Europe.[1] Kerala is the state with the highest recorded cases. However, there has been a rise in the incidence in South Canara district and Assam.[9] The two cases described above hailed from the coastal districts of South India.

Mosquitoes ingest the microfilaria from the blood of an infected host. The third larval form developing in the Malpighian corpuscle passes through the body cavity into the proboscis of the organism, which is transmitted to dogs by the bite. Humans are accidental dead-end hosts.[1],[2] It takes 10 days for the third stage of larva to be formed, and once it burrows into the subcutaneous tissue, it matures in 10–120 days. Based on the severity, it can die or migrate into smaller capillaries and reach cardiac and pulmonary circulation. They can cause lung embolisms and necrotizing granulomas.[10]

Protozoan infections in the breast are very rare.[5],[10] They are usually asymptomatic. However, the severity of the symptoms is related to the site of occurrence.[10] In the subcutaneous infestation, the nodules can vary in from 1.5 to 2 cm in diameter.[10] A single but migratory nodule is the most common presentation and is usually presented after many years of initial infection after the nematode perishes and forms a foreign body granuloma.[2] Sonography of the breast shows cystic lesion with a tubular echogenic architecture.[5]

The examination of histological sections of worms and/or of the infected tissue collected during or following surgery allows the specific diagnosis. In case of D. repens, the typically indented cuticle allows the differentiation from D. immitis. In this species, the cuticular ridges are absent. In both the cases, it showed cuticular ridges on histopathology thus confirming the D. repens species.[7],[8],[9],[10]

Laboratory tests such as polymerase chain reaction (PCR) and ELISA can be used for further genetic studies.[1],[3] In one of the cases reported, histology and cytology showed evidence of granulomas which are the usual findings caused by the dead worm. Studies have been done on nucleic acid extraction.[11] The DNA is extracted from the tissue and the worm using a DNA mini kit, and the total nucleic acid is extracted from peripheral ethylenediaminetetraacetic acid whole-blood sample using the EZ1 mini kit (Qiagen, Hilden, Germany). The DNA is then eluted in 60 μl of elution buffer and used as the template for PCR.[11]

There is no mention of antifilarial medication use in the previous studies.[6] Surgical excision is the best treatment of choice, and chemotherapy is contraindicated as microfilaremia is very rare.[1],[2] There is not much data available on the effects of ivermectin and doxycycline therapy against D. repens. However, it seems that only doxycycline may have a possible adulticidal effect, due to its action on the bacterial endosymbiont, Wolbachia, present in most filarial species including the D. repens.[12] However, some studies shown with ivermectin have 73% adulticide effect.[10],[11],[12] Patients from endemic area should be managed with combination therapy.[11],[12] In our cases, both were treated with doxycycline and ivermectin combination therapy since both were from endemic areas.

Primary prevention of the disease is mosquito control. The use of bed nets and insecticides is mandatory in endemic areas. Prevention can also be achieved by reducing the prevalence of infestations in the animal hosts.[1]

  Conclusion Top

In India, the filarial infections are increasingly identified with many endemic areas and manifested in different sites with unusual presentations warranting personal protective measures and reduction of incidence of the vector. Clinicians, pathologists, and parasitologists should have an increased awareness of this entity, with these infections having unusual manifestations. Various epidemiological surveys for identification of species, molecular studies of species identification, and natural hosts can help to establish low prevalence rate of the emerging zoonosis and devise control measures.

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.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Patel SN, Brahmbhatt MN, Nayak JB, Desai ND, Kaje VS. Human Dirofilariasis: An emerging zoonosis. J Food Borne Zoonotic Dis 2015;3:39-41.  Back to cited text no. 1
Permi HS, Veena S, Prasad HK, Kumar YS, Mohan R, Shetty KJ. Subcutaneous human dirofilariasis due to Dirofilaria repens: Report of two cases. J Glob Infect Dis 2011;3:199-201.  Back to cited text no. 2
Reddy MV. Human dirofilariasis: An emerging zoonosis. Trop Parasitol 2013;3:2-3.  Back to cited text no. 3
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Achappa B, Madi D, Mahalingam S. An interesting case of a subcutaneous nodule. J Clin Diagn Res 2013;7:364-5.  Back to cited text no. 4
Surendrababu NR, Thomas E, Rajinikanth J, Keshava SN. Breast filariasis: Real-time sonographic imaging of the filarial dance. J Clin Ultrasound 2008;36:567-9.  Back to cited text no. 5
Patel R, Singh S, Bhavsar S. A rare case of subconjunctival dirofilariasis by Dirofilaria repens in rural Gujarat. Indian J Ophthalmol 2014;62:649-51.  Back to cited text no. 6
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Padmaja P, Kanagalakshmi, Samuel R, Kuruvilla PJ, Mathai E. Subcutaneous dirofilariasis in Southern India: A case report. Ann Trop Med Parasitol 2005;99:437-40.  Back to cited text no. 7
Khurana S, Singh G, Bhatti HS, Malla N. Human subcutaneous dirofilariasis in India: A report of three cases with brief review of literature. Indian J Med Microbiol 2010;28:394-6.  Back to cited text no. 8
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Joseph E, Matthai A, Abraham LK, Thomas S. Subcutaneous human dirofilariasis. J Parasit Dis 2011;35:140-3.  Back to cited text no. 9
Conly JM, Sekla LH, Low DE. Dirofilariasis presenting as a breast lump. Can Med Assoc J 1984;130:1575-6.  Back to cited text no. 10
Simón F, Siles-Lucas M, Morchón R, González-Miguel J, Mellado I, Carretón E, et al. Human and animal dirofilariasis: The emergence of a zoonotic mosaic. Clin Microbiol Rev 2012;25:507-44.  Back to cited text no. 11
Fontanelli Sulekova L, Gabrielli S, De Angelis M, Milardi GL, Magnani C, Di Marco B, et al. Dirofilaria repens microfilariae from a human node fine-needle aspirate: A case report. BMC Infect Dis 2016;16:248.  Back to cited text no. 12


  [Figure 1], [Figure 2], [Figure 3]


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