Abstract

Diffuse anterior retinoblastoma (Rb) is a rare variant of this tumor which may involve the anterior chamber of the eye without any detectable mass in the posterior segment. The initial presentation of this tumor as anterior segment pathology may lead to misdiagnosis and erroneous management eventually delaying the definitive therapy. We describe an 8-year-old child presenting with complicated cataract who underwent lens aspiration and later found to have diffuse anterior Rb.

Introduction

Retinoblastoma (Rb) is the most common intraocular malignancy of childhood, presenting in children ≤ 3–4 years of age.[1] Classically, Rb presents as a retrolental mass arising from the retina and visible externally as a white pupillary reflex and grows either towards vitreous (endophytic pattern) or towards choroid (exophytic pattern) or a third pattern demonstrating horizontal growth with minimal vertical growth, giving it a diffuse infiltrating appearance.[2],[3] Diffuse anterior Rb is a rare variant wherein the tumor seeds in the peripheral retina from where cells enter the aqueous humor and implant on the ciliary body with resultant seeding of tumor cells in the iris, lens, trabecular meshwork, and the anterior chamber (AC) without an evident retinal mass.[3]

We report a child who presented with complicated cataract, subsequently diagnosed to have diffuse anterior Rb.

Case Report

An 8-year-old male presented with diminution of vision in the left eye of 8-month duration with pain and redness for 2 months. On examination, the visual acuity was 20\20 in the right eye and light perception in the left eye. The intraocular pressure (IOP) was 10 and 30 mmHg in the right and left eye (normal IOP: 10–21 mmHg Slit-lamp examination of the left eye showed cellular reaction, corneal edema and fluffy white exudates stuck to corneal endothelium suggestive of AC inflammation. A white intumescent cataract was remarkable in the left eye precluding the examination of the posterior segment [Figure 1]. The right eye was normal. Ultrasound B-scan of the left eye demonstrated no abnormality in the posterior segment. The general and systemic examination of the child was normal.

| Figure. 1Anterior segment photograph of the left eye of the child showing ciliary and conjunctival congestion. The presence of fluffy white exudates is noted behind the corneal endothelium (solid arrow) along with an intumescent white cataract (dotted arrow)

With a diagnosis of lens-induced uveitis with secondary glaucoma in the left eye, the child was prescribed oral acetazolamide, topical betamethasone 0.1%, homatropine 2%, and timolol 0.5% eyedrops. A planned cataractous lens aspiration with intraocular lens implantation was performed, to reduce the IOP, AC inflammation, and visualization of the posterior segment. The fluffy material from AC sent for cytological examination revealed a discretely scattered population of malignant small blue round cells arranged in small clusters, suggestive of retinoblastoma.

A contrast-enhanced computed tomography scan of the orbits showed no intraocular mass lesion. An ultrasound-biomicroscopic examination of the left eye revealed a ciliary body mass involving 360° of the pars plana region [Figure 2]. Two cycles of neoadjuvant intravenous chemotherapy were administered (carboplatin – 560 mg/m2, vincristine – 1.5 mg/m2, and etoposide – 300 mg/m2, given on a single day, 3 weekly). The left eye underwent enucleation with polymethyl methacrylate implant of 18 mm diameter.

| Figure. 2 Ultrasound biomicroscopic examination of the left eye showing tumor mass (m) arising from ciliary body adjacent to the sclera (s), abutting the posterior surface of the iris (i)

The histopathology of the eyeball showed normal intraocular structures and optic nerve on gross examination. Microscopic examination revealed floating clusters of tumor cells in AC and a tiny focus of tumor tissue attached to the ciliary body. The tumor had a classical cytomorphology of Rb showing round blue cells with high nuclear–cytoplasmic ratio, inconspicuous nucleoli and scant cytoplasm. The apoptotic bodies, foci of necrosis, and calcification were also identified. However, no rosettes were seen. The lamina cribrosa and rest of the optic nerve showed no tumor invasion [Figure 3].

| Figure. 3(a) Low magnification showing tumor (dotted arrow) attached to the ciliary body and a degenerated lens (solid arrow). (b) High magnification showing microscopic tumor foci with cells arranged in sheets. (c) Tumor cells showing nuclear molding and apoptotic debris. (d) No infiltration of the optic nerve or lamina cribrosa was noted

Postoperatively, the child received four additional cycles of adjuvant chemotherapy. At present, the child is well, 5 months post completion of treatment.

| Figure. 1Anterior segment photograph of the left eye of the child showing ciliary and conjunctival congestion. The presence of fluffy white exudates is noted behind the corneal endothelium (solid arrow) along with an intumescent white cataract (dotted arrow)

| Figure. 2 Ultrasound biomicroscopic examination of the left eye showing tumor mass (m) arising from ciliary body adjacent to the sclera (s), abutting the posterior surface of the iris (i)

| Figure. 3(a) Low magnification showing tumor (dotted arrow) attached to the ciliary body and a degenerated lens (solid arrow). (b) High magnification showing microscopic tumor foci with cells arranged in sheets. (c) Tumor cells showing nuclear molding and apoptotic debris. (d) No infiltration of the optic nerve or lamina cribrosa was noted

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