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Editor,—Cysticercus cellulosae, the larval form ofTaenia solium (tapeworm), often affects the human eye. Human infection occurs on eating raw or inadequately cooked infected pork, consuming food or water contaminated with faecal matter containing the ova, or as a result of autoinfection.Sommering first reported a case of ocular cysticercosis.The parasite's most favoured site in the eye is vitreous and subretinal space followed by the subconjunctival tissue.Spontaneous expulsion of cysticercosis from the subconjunctival space and orbit is uncommon. We report a case of subconjunctival cysticercus cellulosae in which there occurred spontaneous extrusion.
A young 7 year boy presented with redness and swelling in the right eye. General physical and systemic examination revealed no abnormality. The right eye had a smooth, pinkish, hemispherical, subconjunctival, cystic swelling of approximately 8×5 mm size near the inner canthus (Fig 1). It was loosely adherent to the eyeball, non-reducible, and was mildly tender. The conjunctival vessels over and around it were mildly congested. The left eye was normal. An ultrasound of the right eye done with a waterbath revealed a subconjunctival cyst with a central echogenic nodule suggestive of a cysticercus cellulosae (Fig 2). Excision of the cyst was planned, but the patient reported a week later with history of spontaneous expulsion of a small balloon-like translucent structure from the eye after which the swelling subsided. Repeat slit lamp examination did not show any swelling in the eye though there was redness and a conjunctival rent close to the inner canthus. An ultrasound examination was normal and the cyst seen earlier was not present.
Cysticercosis has a global distribution particularly in countries where there is increased incidence of pork eating. Ocular dissemination of cysticercus celluosae is well known and is evident from several reports in the literature. The most favoured site is the vitreous and subretinal space followed by subconjunctival tissue and extraocular muscles. The cysticercus in the present case was subconjunctival and there was spontaneous expulsion. Since 1970 only six cases of spontaneous extrusion of cysticercus from subconjunctival space have been reported. In the three cases reported by Bansalet al the cyst was located within the medial rectus muscle in the first case, in the subconjunctival space in the second case, and in the superior orbit in the third case from where they were extruded. In the present case the cystic swelling was present near the inner canthus of the eye with attachment to the underlying muscle sheath.
In orbital and subconjunctival cysticercosis the cyst is usually attached to the muscle sheath, where it induces an inflammatory reaction and because of its constant motility it erodes through the conjunctiva and comes out leaving a rent in the conjunctiva which ultimately heals within a short period. This case report highlights the importance of ultrasound in such lesions and should be the primary mode of investigation. On ultrasound the cyst is seen as a sonolucent area with well defined anterior and posterior margin with the presence of a central echodense, curvilinear highly reflective structure within the cyst, that of a scolex.