Dirofilariasis is a known parasite that affects the ocular and periocular tissues.12345 Man is a dead end for the parasite and it causes severe inflammatory reaction in the host. It has been reported in the subcutaneous tissue,5 subconjunctival space,12 and as an intraocular parasite. Such lesions are always associated with moderate to severe inflammation.3 We report a case of periocular Dirofilariasis in a healthy Asian Indian woman that presented as a slow growing non-inflammatory mass lesion.
A 78-year-old healthy female presented to us with mild pain and irritation in her left eye. She was a hypertensive on treatment. Best-corrected visual acuity was 6/9, N6 in both the eyes. Slitlamp examination showed nuclear sclerosis in both the eyes. Palpation of left upper eyelid showed an ill-defined non-tender mass in the lacrimal gland area, which was ignored as a palpable lacrimal gland. She was treated with topical Ofloxacin eye drops for mild meibominitis. When she was reviewed a month later the mass had increased in size, now measuring about 1.5cm x 0.5 cm in size. It was still painless, non-tender and non-inflammatory (Figure 1 top). Investigations including haemoglobin, total count, differential count, erythrocyte sedimentation rate (ESR), chest X-ray, Mantoux test, peripheral smear, and antinuclear antibody were within normal limits. Systemic evaluation by oncologist ruled out any mass lesion in the breast and abdomen. A clinical diagnosis of lacrimal gland tumour was kept in mind. She was reviewed after a month and the mass had further enlarged in size. It was a firm swelling in the subcutaneous region in the superolateral part of orbit. The posterior margin was palpable. A computed tomogram showed an ellipsoid mass 15.9 x 7.4 mm in size, which was hyperdense and situated anterior and temporal to the left eyeball arising from the posterior aspect of eyelid. The mass was not in proximity to the optic nerve or ocular muscles and was separate from the lacrimal gland but connected to it by a septum. (Figure 1, bottom).
The differential diagnoses considered were sebaceous cyst, secondaries from an occult primary, and tumours of the lacrimal gland. She was advised excision biopsy. The mass was excised in toto. It was a well circum-scribed capsulated tumour adherent to the skin and to orbicularis oculi. The conjunctiva was free and not inflamed. On opening the capsule, a thin thread-like non-motile dead parasite was seen. Histopathologically it was identified as Dirofilaria conjunctivae species, (Figure 2 right). The parasite was 0.5 mm thick and 10 mm long. Under the light microscope the cephalic end showed no lips and head papillae were not prominent. The oesophagus was short. The vulva was a little behind the oesophagus. Multiple sections of the parasite were taken. It was surrounded by a thick cuticle with multiple small transverse ridges. Underneath the cuticle, a thick muscular layer was seen. Some sections showed portions of the intestine as well as uterine cavity. The features were consistent with female species of Dirofilaria conjunctiva. Surrounding tissue showed chronic inflammatory cells, predominantly lymphocytes with few plasma cells, eosinophils and epithelioid cells. There were areas of necrosis (Figure 2, left). At the last follow up six months after the excision biopsy, the visual acuity in the left eye was 6/9, N6 and external eye examination did not reveal any residual swelling.
Dirofilaria is well known to affect the eye and the adnexa.5 Periocular Dirofilariasis usually presents as an inflammatory painful mass lesion and the differential diagnosis includes inflammatory pseudotumour,5 ruptured dermoid cyst and an infectious abscess. In contrast the case reported here presented clinically as a non inflammatory lid tumour. Since the patient was an elderly lady the immune system might not have reacted to the parasite with severe inflammation. Dirofilariasis should be considered in the differential diagnosis of non-inflammatory mass lesions of the ocular adnexa. Our report describe another uncommon presentation of a parasitic infestation in the ocular adnexa.
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Proprietary Interest: None