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PUBLICATION EXCLUSIVE: Chemotherapy can suppress inflammatory signs of periocular filariasis
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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.
Images: Agarwal A
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.
- Click here to read the full publication exclusive, Complications Consult, published in Ocular Surgery News U.S. Edition, November 10, 2016.