Correspondence Address:
Praneet Awake
Department of Venereology and Leprosy, Symbiosis Medical College for Women, Symbiosis International (Deemed University), Pune, Maharashtra
India

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Sir,

We report a case of 36-year-old man who presented to dermatology outpatient with complaints of an asymptomatic peri-orbital nodule over left lateral side of nose near medial canthus of left eye since one-month duration. Ophthalmic examination of the left eye and surrounding region revealed subcutaneous non-tender, mobile, non-adherent, nodule over the left lateral side of nose [Figure 1]. Ocular movements and acuity were normal without any proptosis. General and systemic examination was within normal limits. Routine haematological investigations, chest radiograph and abdominal ultrasound were within normal limits. Clinically dermoid cyst and lipoma were considered.{Figure 1}

Magnetic Resonance Imaging (MRI) orbits showed a well circumscribed oval cyst measuring 6 × 7 × 10 mm in subcutaneous plane along lateral aspect of nose on the left side with thin imperceptible wall and no evidence of restricted diffusion, without calcification and intraorbital extension [Figure 2].{Figure 2}

A single, encapsulated, grey white tissue bit measuring – 1 × 0.5 × 0.5 cm was removed surgically and sent for histopathology. On cut section homogenous whitish brown necrotic areas were observed.

Histological examination showed a thick walled cyst, lined by flattened cuboidal epithelium and composed of dense mixed inflammatory exudate with infiltration by histiocytes, mononuclear cells, and occasional eosinophil. The lumen showed multiple cross sections of a parasite having outer thick multi-layered cuticle with longitudinal ridges, internal muscle layer with lateral chords and a gastrointestinal tract, suggestive of Dirofilaria repens [Figure 3]a and [Figure 3]b. However, due to necrosis full worm could not be obtained. Postoperative recovery was uneventful [Figure 4].{Figure 3}{Figure 4}

Dirofilaria is a zoonotic helminth which naturally infects dogs, cats and other wild mammals [Table 1].[1] Humans may accidentally get infected from mosquito bite. The genus Dirofilaria consists of D. immitis, D. repens. D. immitis which can cause pulmonary lesion whereas D. repens cause ocular lesions. Subcutaneous lesions are very rare and often go unnoticed as they rarely produce any symptoms.[2] Human dirofilariasis has been reported to be an emerging zoonotic infection in India since past few decades.[3] Human subcutaneous infection with Dirofilaria is comparatively rare in western India. Maximum number of cases have been reported from Kerala in South India.[3]{Table 1}

Ocular involvement is more commonly reported as the swelling around eyes draws immediate attention. The worm may be present in the subconjunctival, periorbital, periocular, sub-tenon or intraocular regions. Localized itching, pain and swelling are the most commonly symptoms reported.

D. repens are usually found in subcutaneous tissue and have characteristic longitudinal cuticular ridges.[4] The important anatomical features are seen in the transverse sections of the worms. The living worms have a multilayered cuticle about 6–8 μm in thickness; the longitudinal ridges are low, smoothly rounded, and about 9–10 μm apart. On the inner surface of the cuticle in the lateral fields, there is a conspicuous cuticular ridge that protrudes into the inner surface of lateral chords.[5]

The definite diagnosis can be made after surgical excision and examination of worm.[6] Elevated serum immunoglobulin E levels and blood eosinophilia or are seldom observed. In our case, surgical removal of the embedded necrosed worm and tissue mass was done. Prognosis is usually good in case of subcutaneous Dirofilariasis. We report this case to create awareness about the condition, which should be considered in any patient presenting with single, often asymptomatic, subcutaneous nodule.

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