Hemorrhagic intraretinal macrocyst: Differential diagnoses and report of an unusual case.

Retinal 'cysts' may be single or multiple, ranging from two-to-ten disc diameters in size, and occur in eyes with longstanding retinal detachment. The authors describe a retinal macrocyst larger than ten disc diameters, with a blood-filled cavity, and its ultrasound findings. Improved retinal nourishment following retinal reattachment gradually reverses the process responsible for cystic degeneration, with the eventual collapse of the cyst (within days or weeks). Surprisingly, this giant cyst did not collapse for almost three years despite retinal reattachment. The internal mobile echogenic contents were suggestive of blood. The possible reason of blood in the cyst could be rupture of the retinal blood vessels in the cyst cavity. This could be a recurrent phenomenon, which did not allow the cyst to collapse. The Hemorrhagic Intraretinal Macrocyst needs to be differentiated from mimicking clinical conditions, namely, retinoschisis, choroidal melanoma, subretinal abscess, choroidal hemangioma, and the like. It could take up to a few years to collapse spontaneously, following successful retinal reattachment.

Introduction

Retinal ‘cysts’ may be single or multiple, ranging from two-to-ten disc diameters in size and occur in 1-3% of the eyes with longstanding retinal detachment.[12] Once the retina reattaches, the intraretinal cysts disappear in a few weeks. We hereby report a case of an intraretinal macrocyst, larger than 10-disc diameters, containing blood. The cyst took three years to collapse, despite successful scleral buckling.

Case Report

A 30-year-old male was evaluated for floaters and decreased vision in his right eye, of one-month duration. He had sustained trivial trauma in that eye two years back. Best-corrected visual acuity was 20 / 60. Slit lamp biomicroscopy showed an early, posterior subcapsular cataract, and a mild, relative afferent pupillary defect. The left eye was essentially normal. The right fundus showed nasal-half retinal detachment with demarcation lines. A large macrocyst containing organized blood, and extending almost up to the ora serrata was seen in the superonasal quadrant [Figure 1]. A retinal dialysis was noted superiorly [Figure 2]. The cyst, orange-yellow in color was well-delineated, immobile, non-translucent, and showed no blanching on pressure. An ultrasound confirmed the presence of a well-demarcated, oval, cystic lesion within the retina, measuring 12.7 mm circumferentially and 7.4 mm anteroposteriorly [Figure 3]. Surface reflectivity was high and intralesion echoes were low-to-moderately reflective. Fluorescein angiography revealed blocked choroidal fluorescence in the area of the cyst with a lack of double circulation within it [Figure 4].

Figure 1

A red free fundus photograph of the right eye reveals a mass lesion in the nasal quadrant (arrowheads)

Figure 2

Schematic representation of the fundus appearance of the right eye at presentation. White area denotes attached retina. Light grey area denotes detached retina. Dark area denotes retinal dialysis. Stippled line denotes demarcation line. Shaded area denotes hemorrhagic intraretinal macrocyst

Figure 3

Ultrasound scan of the right eye at presentation. A well-delineated cystic mass lesion measuring 12.2 mm × 7.4 mm is noted. It has a high surface reflectivity and low-to-moderate internal reflectivity with an irregular echotexture. Retinal detachment is noted inferior to the lesion (arrow)

Figure 4

A late phase fluorescein angiographic image showing blocked fluorescence in the area of the lesion as well as lack of double circulation within the lesion (arrowheads)

The patient underwent scleral buckling (# 279 solid silicone) with cryopexy to retinal dialysis and subretinal fluid drainage. The cyst was not drained. In the immediate postoperative period, the retina was attached except for a small pocket of subretinal fluid in the inferonasal quadrant. The cyst did not undergo any change. Two months postoperatively, the fundus remained unchanged. Best-corrected visual acuity was 20 / 30 and the cyst measured 12.1 mm circumferentially and 6.7 mm anteroposteriorly [Figure 5]. The findings remained unchanged until 19 months, postoperatively. Three years after surgery, his best-corrected visual acuity was 20 / 40; the retina was completely attached and no intraretinal cyst was evident [Figure 6].

Figure 5

Ultrasound scan of the right eye two months after surgery. The retinal ‘cyst’ is persistent. An echolucent area in the orbit adjacently behind the ‘cyst’ denotes the scleral buckle (arrow)

Figure 6

Ultrasound scan of the right eye three years after surgery. Acoustically clear vitreous cavity with complete retinal re-attachment and resolution of retinal ‘cyst’ is noted

Discussion

Hager and North[3] have reported that macrocysts (medium-sized isolated cysts) are almost always seen in longstanding retinal detachments (usually greater than three months duration). They are found in about 3% of the eyes undergoing retinal detachment surgery. Macrocysts are believed to result from secondary degenerative changes in the retina. Retinal macrocysts are fluid-filled cavities, that is not very different from the subretinal fluid.[45] Occasionally, there may be blood within the cyst.[4] Drainage of the cyst is not indicated, as most cysts spontaneously resolve upon retinal reattachment and improved nutrition of the retina.[3]

Pischel[6] classified retinal cysts into small (up to 1 mm in size), medium or isolated (four to eight disc diameters), giant (eight to ten disc diameters or more), and large cysts (retinoschisis) occupying 25% of the fundus.

Keith[7] proposed classifying the lesions into, ′Retinal cysts and Retinoschisis′. He described cyst formation following retinal detachment and doubted the causation of retinal disinsertion by the pre-existing retinal cyst. Zimmerman and Spencer[8] reported two unusual cases, which were diagnosed as malignant melanoma of the choroid and treated with enucleation, to be retinoschisis, which gave rise to a clinical picture of the tumor.

Ruiz[4] reported enucleation of a blind eye with longstanding retinal detachment diagnosed clinically as malignant melanoma, which on histopathological examination turned out to be a macrocyst of the retina with organized hemorrhage.

Marcus and Aaberg,[5] published a case series of seven patients, with retinal ′cysts′ associated with traumatic retinal detachment. In four of the seven eyes, the cysts were drained as they were felt to mechanically prevent closure of the retinal break. Hemorrhagic retinal cysts have also been described pathologically in eyes enucleated for advanced Coats disease.[59-11] The pathogenesis of a retinal cyst has been attributed to cystoid degeneration in the detached retina. In a series of seven eyes with intraretinal macrocysts associated with retinal detachment, reported by Marcus and Aaberg,[5] none of the patients had a hemorrhagic cyst. A pathological study of one eye demonstrated that retinal macrocysts originated from the outer plexiform layer. Although four of the seven cases in their series required drainage of the macrocysts to flatten the retinal break, we did not have to do so in our patient.

Differential Diagnoses

Macrocysts need to be differentiated from retinoschisis. In a macrocyst, there is no typical predilection for the inferotemporal quadranthyperopia or bilaterality, no vascular sheathing, glistening white spots, or retinal holes are seen, as in retinoschisis.

Clinically, and especially in eyes with opaque media, they may be confused with malignant melanoma, circumscribed choroidal haemangioma, subretinal abscess or posterior scleritis. The characteristic ultrasound features of each entity may help differentiate one from the other.

Malignant melanoma appears as a dome-shaped mass with a collar-stud appearance and a secondary retinal detachment away from the summit of the tumor mass. It has high surface reflectivity and low-to-moderate internal reflectivity. Acoustic hollowing with angle kappa may be seen. Choroidal excavation may also be noted. It may have extrascleral extension. In our patient, the ultrasound showed the origin of the cyst from within the retina and not the choroid. Splitting of the retina into two layers was noticeable with internal echogenic contents attributable to altered hemorrhage [Figure 7].

Figure 7

Ultrasound scan of the reported eye reveals retinal detachment with splitting (arrow) of the retinal layers to form a retinal cyst. Internal mobile echogenic signals within the cyst represent blood

A circumscribed choroidal hemangioma appears as a relatively non-homogenous choroidal mass lesion with high surface reflectivity and moderate-to-high internal reflectivity. It may be associated with secondary retinal detachment.

A sub-retinal abscess typically appears as a well-defined, dome-shaped, elevated mass lesion, with high surface reflectivity and moderate-to-high internal reflectivity. A localized hypoechoic area of subtenon space widening is noted, adjacent to the lesion.

Posterior scleritis typically appears as a lesion with high surface reflectivity, with a regular, high internal reflective structure at the scleral level and may be associated with a localized increase in the sub-Tenon's space.

To our knowledge, a hemorrhagic retinal cyst of more than ten disc diameters, with ultrasound documentation of such a lesion, has not been reported to date.

It is known that after retinal reattachment, improved nourishment of the retina gradually reverses the process responsible for cystic degeneration with eventual collapse of the cyst. Surprisingly this giant cyst did not collapse for almost three years, despite retinal reattachment. The possible reason of blood in the cyst could be a rupture of the retinal blood vessels in the cyst cavity. This could be a recurrent phenomenon, not allowing the cyst to collapse.

In conclusion, a hemorrhagic intraretinal macrocyst needs to be differentiated from mimicking clinical conditions. It may take up to a few years to collapse spontaneously, following successful retinal reattachment.