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Some posterior segment lesions mimic torpedo maculopathy
Clinical examination is usually sufficient to differentiate types of lesions.
Torpedo maculopathy can be distinguished from other posterior segment lesions with similar features, according to a report.
Congenital hypertrophy of the retinal pigment epithelium (CHRPE) and retinal pigment epithelial (RPE) lesions of Gardner syndrome may resemble torpedo maculopathy in clinical examination.
“These are somewhat common lesions that are found usually asymptomatically in children and adults, and they superficially look similar to each other,” Stephen G. Schwartz, MD, MBA, the corresponding author, said in an interview with Ocular Surgery News.
Optical coherence tomography and fundus autofluorescence can be used to distinguish torpedo maculopathy from CHRPE or RPE lesions of Gardner syndrome, but imaging may not be necessary, Schwartz said.
“I think OCT is helpful in distinguishing the lesions apart from each other, but it may not be necessary,” he said. “The clinical characteristics are often enough to tell them apart pretty accurately. … None of them tend to grow, and none of them typically turn malignant.”
However, differentiating RPE lesions of Gardner syndrome from the other lesions is important, Schwartz said.
“I think the important entity to try to distinguish from all the other ones because of the potential systemic implications is the RPE lesions of Gardner syndrome,” he said.
The report was published in Ophthalmic Surgery, Lasers and Imaging Retina.
Torpedo maculopathy
Torpedo maculopathy is a congenital solitary flat oval-shaped lesion with well-defined margins. It is typically unilateral.
“The torpedo lesions tend to be just temporal to the center of the macula,” Schwartz said. “They tend to have that head and that tail, with the head pointing toward the fovea and the tail pointing away.”
Most lesions are hypopigmented, but some are hyperpigmented, particularly at the tail. Lesions are typically longer in the horizontal axis than in the vertical axis.
Lesions involving the fovea or systemic associations have not been reported.
OCT images of torpedo maculopathy show outer retinal structural abnormalities such as thinning of the retina and RPE, photoreceptor loss, outer retinal clefts and increased reflectivity of the choroid.
Fundus autofluorescence images show hypoautofluorescence of the lesion, and a window defect is frequently seen with fluorescein angiography. Visual fields often show corresponding scotomas.
CHRPE
CHRPE is usually unilateral and asymptomatic, featuring a flat, variably pigmented lesion at the level of the RPE, often with depigmented lacunae and/or a depigmented halo.
“You can have multiple CHRPE lesions in an eye, sometimes referred to as ‘bear tracks.’ Every once in a while they have a white color, and it may be referred to as ‘polar bear tracks.’ They’re essentially the same finding,” Schwartz said.
OCT images of CHRPE show retinal thinning, photoreceptor loss, disorganized retinal anatomy, increased RPE thickness and decreased reflectivity of the choroid. Choroidal cavitation has also been reported on OCT.
Fundus autofluorescence images feature hypoautofluorescence, but the lacunae may show mild hyperautofluorescence. It also typically features blocking, although the lacunae may show small window defects. A corresponding visual field defect is involved.
Gardner syndrome
RPE lesions of Gardner syndrome are normally bilateral. They are usually multiple, smaller than 1 mm, flat, ovoid or round, and appear mainly in the equator and midperiphery. Some lesions have a hypopigmented halo or a hypopigmented tapered tail that may point in any direction.
RPE lesions of Gardner syndrome may appear similar to “bear tracks,” but they can usually be distinguished. Bear tracks are generally peripheral, unilateral and sectoral, while RPE lesions of Gardner syndrome are typically posterior, bilateral and more widespread, according to Schwartz. In addition RPE lesions of Gardner syndrome may be more variable in appearance than bear tracks.
OCT characteristics of RPE lesions of Gardner syndrome have not been previously reported, but Schwartz and colleagues presented a case with retinal thinning, photoreceptor loss and increased RPE thickness.
“It is important to distinguish between the lesions when possible,” Schwartz said. “Torpedo maculopathy, CHRPE and bear tracks are generally benign and may be observed, while patients with RPE lesions of Gardner syndrome may be at risk for serious systemic illness, and further workup should be considered, including APC genetic testing and referral to a gastroenterologist.” – by Matt Hasson
Reference:
Villegas VM, et al. Ophthalmic Surg Lasers Imaging Retina. 2014;doi:10.3928/23258160-20140410-01.For more information:
Stephen G. Schwartz, MD, MBA, can be reached at Bascom Palmer Eye Institute, 311 9th St. North, Suite 100, Naples, FL 34102; 239-659-3937; email: sschwartz2@med.miami.edu.Disclosure: Schwartz is a consultant for Bausch + Lomb and Santen and is a speaker for ThromboGenics.
Perspective
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Torpedo maculopathy is rare. A PubMed search on the term identifies fewer than 20 papers on the topic. However, because most patients have normal vision and are asymptomatic, cases are likely under ascertained, and it is almost certainly more common than the small number of case reports implies.
This report by Villegas and colleagues focuses on the differential diagnosis of the lesion. The most common simulating conditions include CHRPE and the RPE changes seen in patients with Gardner syndrome. CHRPE typically demonstrates hyperpigmentation, although there may be depigmented lacunae or a hypopigmented halo; the torpedo lesion has a hypopigmented head, although the tail may demonstrate variable pigmentation.
Gardner lesions, although they may have a similar appearance to torpedo lesions, tend to be multiple and bilateral and most often are located in the midperiphery. The torpedo maculopathy lesion is solitary and located just temporal to the macula.
Based on these differences, it should be possible to differentiate torpedo maculopathy from the two most common simulating diagnoses.