Chemotherapy can suppress inflammatory signs of periocular filariasis

Issue: November 10, 2016

ByDhivya Ashok Kumar, MD, FRCS, FICO, FAICO

ByAmar Agarwal, MS, FRCS, FRCOphth

ByKanchan Solanki, DO

Dirofilaria repens is an endemic parasite in Mediterranean countries that mostly affects animals. Dirofilaria is a genus of the family Onchocercidae of the super family Filarioidea, order Spirurida in the subphylum Nematoda. Rarely, it can infect humans, causing inflammatory subcutaneous swelling. Human ocular dirofilariasis is sporadically reported in different parts of the world. The species affecting humans are D. immitis, D. repens, D. striata, D. tenuis, D. ursi and D. spectans. The most common presentation is an inflammatory swelling of the ocular adnexa. We report a non-inflammatory presentation of dirofilariasis in the lid mimicking as lipoma in a patient on cancer chemotherapy.

Case report

A 67-year-old man presented with complaints of painless swelling in the lower lid of the right eye, with the swelling gradually increasing in size. Best corrected visual acuity was 6/9 in the right eye and 6/6 in the left eye. Other ocular findings were within normal limits, except for a history of cataract surgery. He was a known case of carcinoma bladder treated with chemotherapy. There was no history of pain, tenderness or fever. There was no history suggestive of moving worms feeling. Ocular examination showed a swelling size of 2 cm × 2 cm (Figure 1). On palpation, the swelling was non-tender, well-defined, soft to firm in consistency and freely mobile in all directions. The differential diagnosis considered was a lipoma, and excision biopsy was undertaken.

Gross examination

It was a well-encapsulated mass with yellowish tinge about 2 cm × 1.7 cm and was soft in consistency (Figure 2).

Histopathology

The histopathological report showed fibroadipose tissue and skeletal muscle bundles with cut sections of three filarial parasites. All three parasites showed a smooth, thick multilayered cuticle, a muscle layer with transverse striations and morphological features suggestive of Dirofilaria repens (Figure 3). Each parasite was surrounded by a dense mixed inflammatory infiltrate comprising lymphocytes, neutrophils, plasma cells, eosinophils and histiocytes. Cross sections showed a double uterus and central intestinal tubes.

Figure 1. Preoperative picture of right lower lid subcutaneous mass.

Figure 2. Mass removed in toto measured size 20 mm × 17 mm.

Figure 3. Histopathology section of the mass showing three Dirofilaria parasites surrounded by inflammatory exudates (hematoxylin and eosin stain, 40X). Cross section shows thick cuticle and muscular layer.

Systemic assessment

A routine blood examination was within normal limits except for elevated ESR of 21 mm/h at 1 hour. Blood serology for dirofilariasis was found to be negative. The patient was sent to the infectious disease department for systemic evaluation of dirofilariasis, and there was no systemic filariasis detected. Postoperatively, CT scan of the orbit and brain was normal.

Dirofilariasis

The life cycle of Dirofilaria species comprises a definitive vertebrate host and a vector. Both D. immitis and D. repens demonstrate poor vertebrate host specificity given that they can infect numerous mammalian species. Among mammalian hosts, they are best adapted to domesticated and wild dogs, which function as reservoirs. Humans and cats are less suitable hosts because parasite development is dramatically modified compared with the patterns in dogs. The vectors are females of various mosquito species of the Culicidae family. The Dirofilaria are accidentally transmitted to humans by the bite of mosquitoes carrying infective larvae. Dirofilaria cannot mature fully in human tissue and die before producing microfilaria.

Ocular dirofilariasis

Most cases of ophthalmic infection present with pain in the eye, redness, sometimes blurred vision and swelling of the eyelids, which coincides with the worm entering the subconjunctival space. Ocular presentation can be in the form of subconjunctival cysts, eyelid swelling, anterior chamber nodules, painful inflammatory swelling and abscess in subcutaneous tissue. Pauly and colleagues reported a case of dirofilariasis mimicking lacrimal mucocele, and Mahesh and colleagues reported it mimicking as a lid tumor. Most of the eyelid subcutaneous dirofilariasis swelling was associated with inflammatory signs of the eye.

Immunosuppression by chemotherapy

Because the patient in our case had been treated with chemotherapy and radiotherapy earlier, the immune system did not react to the worm causing inflammation. Chemotherapeutic agents are used widely in clinical medicine and oncology for the treatment of conditions in which cytotoxicity activity on the neoplastic cell is the objective. The chemotherapy is given in the form of ionizing radiation or systemic drugs. In both ways, the agents have the tendency to suppress the humoral and cellular responses of the body. An unfortunate sequela of chemotherapy-induced immunosuppression is an increased susceptibility of the host to opportunistic pathogens. Apart from malignancy, chemotherapy is indicated for immunologically mediated disease, lymphoproliferative diseases and prevention of graft rejection.

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Conclusion

Our case report is also about the unusual presentation of a non-inflammatory swelling with blood serology being negative for dirofilariasis rarely due to immunosuppression as a part of comorbidity (in this case, carcinoma of the bladder). Hence, clinicians should be aware of the possibility of this zoonotic infection in cases of localized nodules of any part of the body.

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For more information:
Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: dragarwal@vsnl.com; website: www.dragarwal.com.

Disclosure: No products or companies that would require financial disclosure are mentioned in this article.