Degenerated Intravitreal Cysticercus Cyst Masquerading as Endogenous Endophthalmitis

Abstract

The authors report a case of degenerated intravitreal cysticercus cyst presenting as endogenous endophthalmitis, which has hitherto been unreported. A young adult presented with symptoms of chronic bilateral ocular inflammation, and was treated topically for endogenous endophthalmitis in the left eye. On dilated fundus examination the right eye was found to have a cystic structure in the inferior vitreous cavity. The cyst was removed by a three-port vitrectomy. On submitting the vitreous sample to histopathology it was confirmed to be degenerated cysticerus cyst with chronic inflammation.

KEYWORDS::

• Cysticercosis
• Degenerated cyst
• Endogenous endophthalmitis
• Pars plana vitrectomy
• Transscleral cryotherapy

Cysticercosis is caused by Cysticercus cellulosae, the larval form of the pork tapeworm, Taenia solium. Ocular cysticercosis can involve any part of the eye. According to one study the involvement was subconjunctival, 62.7%; intraocular, 26.3%; orbital, 7%; and lid, 4%.⁴ The intraocular location of the cyst causes retinal detachment, macular scarring,¹,² retinal vasculitis, and vitritis.³ We report here a case of intraocular cysticercosis, which presented with features of endogenous endophthalmitis. To the best of our knowledge this is a rare report of degenerated cysticerus cyst masquerading as endogenous endophthalmitis.

CASE REPORT

An 18-year-old student presented to us with gradual diminution of vision in both eyes for 1 year associated with mild pain and occasional floaters. His past ophthalmic history revealed an attack of redness in the left eye associated with diminution of vision 1 year back, followed by redness in the right eye. Initially he was treated symptomatically by topical medications. He was diagnosed as having left eye endogeneous endophthalmitis by a local ophthalmologist. Subsequently he underwent left eye vitrectomy with intravitreal antibiotics 6 months back. In both eyes he was given intravitreal triamcinolone acetonide injection (IVTA) around 3 months back. He was also diagnosed to have systemic tuberculosis and had been on systemic antitubercular treatment (ATT) for 8 months. One month back he underwent left eye cataract surgery with posterior chamber intraocular lens (PCIOL) implantation.

On examination, he had a best-corrected visual acuity (BCVA) of 3/60, N12 in right eye improving with pinhole to 6/60, and PL +ve, PR accurate, < N36 in the left eye. The anterior segment examination of the right eye with slit lamp revealed lid edema, conjunctival congestion, pigments over corneal endothelium, anterior chamber cells 2+, flare 2+, cataractous lens, and vitreous cells 2+. The left eye showed quiet anterior segment with few pigments over endothelium, and PCIOL with thick posterior capsular opacification was seen. Intraocular pressure (IOP) with Goldmann’s applanation tonometry in the right eye was 19 mmHg and was unrecordable in the left eye. Fundus examination of the right eye with indirect ophthalmoscopy showed pale optic disc, vitreous membranes, and an oblong cystic structure in the inferior vitreous cavity with no motility; the retina was attached throughout. The left eye had very hazy view, which showed total retinal detachment with 360-degree choroidal detachment. A fundus photo (Figure 1) was not clear due to media haze. Ultrasound B scan examination (Figure 2) of the right eye showed a moderate number of dot and few membranous echoes in the vitreous cavity, and a cystic echo with high reflective clump at the edge noted at the inferior vitreous cavity. Retina, optic nerve head (ONH), and choroid were normal and axial length was 22 mm. The left eye showed total retinal detachment with thickened leaflets and bridging membranes. Shallow serous 360-degree choroidal detachment noted. Widening of ONH and axial length of 13.1 mm noted. A provisional diagnosis of right eye intraocular parasite was made and we ordered a CT scan of the brain and orbit, which turned out to be normal. Considering the poor economical status of the patient and since the intraocular parasite was not motile (MRI to be selected for living stage and CT scan to be selected for nonliving stage of the ocular cysticercosis), MRI was not done. He underwent OD: vitrectomy (23G) + intravitreal cyst removal + transscleral cryotherapy (TSC) under general anesthesia. The cyst was delivered by UTQ sclerotomy after enlarging it to 20G. TSC was done to the inferior quadrant. Postoperative course was uneventful. The patient was started on topical prednisolone acetate, ciprofloxacin eyedrops and systemic steroids (prednisolone 60 mg/day in tapering dose), antibiotics (amoxycilline 250 mg qid), and analgesics. Postoperative systemic steroids were started in view of inflammation in the right eye. Histopathology examination showed a degenerated cyst lined by fibrocollagenous tissue (Figure 3). The cyst contained hooklets and the cyst wall contained lymphocytic infiltration. The rest of the routine blood and urine tests were within normal limits. Based on the history, clinical examination, and investigations a diagnosis of cysticercosis of the right eye was made. Based on the similar history in the left eye, we suspected a similar diagnosis as in the past. The patient was referred to an internist to look for any systemic foci for cysticercosis.

FIGURE 1  Color photograph of the right fundus of the patient showing whitish cystic lesion in the inferior quadrant in hazy view due to media haze.

FIGURE 2  B-scan ultrasonography with vector A scan showing a cystic echo with high reflective clump at the edge noted at the inferior vitreous cavity.

FIGURE 3  Vitreous sample showing a cyst lined by fibrocollagenous tissue. Cyst contains hooklets (arrow). Cyst wall contains lymphocytic infiltration (hematoxylin and eosin [H&E], 200× with polarized light).

DISCUSSION

Cysticercosis is a parasitic infection caused by Cysticercus cellulosae, the larval form of the cestode Taenia solium.¹ Taxonomically, taeniasis (infection by the adult worm) must be differentiated from the cysticercosis (infection by the larvae). However, patients may harbor both taeniasis and cysticercosis. Taeniasis is an intestinal infection caused by consumption of the adult worm through undercooked pork and is not associated with ocular disease. In cysticercosis, humans act as an intermediate host following the consumption of eggs in contaminated food or water. After ingestion, the eggs hatch and mature to larvae, which are carried by mesenteric vessels to various parts of the body, where they are filtered through subcutaneous and intramuscular tissues, with preference for the brain and eyes.⁸ Ocular disease is reported to occur in a significant number of cases of cysticercosis. Ocular or adnexal involvement occurs in 13–46% of patients.³ Reportedly, 35% of the cysts are in the subretinal space, 22% in the vitreous, 22% in the subconjunctival space, 5% in the anterior segment, and 1% in the orbit.³ Among the intraocular cysts, 60% are found intravitreally and 40% are subretinal.¹ In our case the cyst was seen in the inferior vitreous cavity with no retinal scar. It is postulated that such a cyst could have entered the eye through the vessels of the ciliary body.¹ The cysts did not show any movement. The central scolex was visible neither clinically nor on ultrasound B-scan.

Magnetic resonance imaging is a useful adjunct to B-scan ultrasonography in the diagnosis of ocular cysticercosis. Magnetic resonance imaging is superior to computed tomography in the demonstration of cystic structures in the eye and central nervous system. This finding has important therapeutic implications, as any viable cysticercus in the eye or cerebral parenchyma can be treated surgically or medically, respectively.⁹

Image appearances of ocular cysticercosis depend on the parasitic site and living status of cysticercus in the eye region. For diagnosis, B-ultrasonography may first be selected, then MRI secondly selected for the living stage and CT secondly selected for nonliving stage of the ocular cysticercosis.¹⁰

The above features and the presence of inflammation suggest a dead and degenerating cyst. There are reports of dead and degenerating cysticerci causing severe inflammatory reaction and ultimately loss of the eye.⁵,⁶ The cysts are known to release toxic products that cause severe inflammation mimicking even intraocular tumor.⁷

Our patient may have been harboring the dead cysticercus cyst for a prolonged period, causing a low-grade inflammation. As a result the patient presented with the symptoms chronic ocular inflammation No visual symptoms from the cyst were noted presumably due to the location of the cyst.

Removal of the cyst is mandatory to remove the source of the toxins causing inflammation, and early removal has been advocated by many authors.¹,⁵ Destruction of the larvae in situ by photocoagulation,¹¹ cryotherapy, and diathermy has been attempted with some success. However, as intraocular cysticercosis may lead to severe inflammation following larval death, early surgical removal of the cyst is the treatment of choice.¹

In the treatment of intraocular cysticercosis, the most common surgical approach is removal through the pars plana route following vitrectomy. Subretinal cysts anterior to the equator may be removed transsclerally, whereas subretinal cysts posterior to the equator and intravitreal cysts are best removed transvitreally.¹ Ideally, the cyst should be removed in toto. Complete surgical removal of the intact cyst results in good functional recovery in eyes with intraocular cysticercosis.¹²

We are unaware of any previous reports of a similar nature involving degenerated cysticerus cyst masquerading as endogenous endophthalmitis and could find no reference to it in PUBMED search. Our patient was one-eyed with the only seeing eye affected concurrently. This prompted us to do an urgent vitrectomy.

In conclusion, a high index of suspicion is required for the diagnosis of ocular cysticercosis in endemic countries. Intact removal of the cyst is mandatory to prevent its propagation.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.