Discussion:
The hamartomas present themselves in a heterogeneous way, being
classified in three groups. Type 1 is relatively flat, without
calcifications and translucent gray-white. Type 2 is elevated,
multinodular, calcified, opaque and “blackberry” shaped. Finally, type
3 characterizes a transitional lesion between those already mentioned.
Type 1 injury has been described as the most common form, occurring in
up to 70% of cases. Type 2 represents 55% and type 3, 9% of
patients6. Zhang et al showed the prevalence of type 1
RAH in 94% of cases, type 2 in 7% and type 3 in
19%7. These results coincided with the prevalence
reported by Kiribuchi et al in Japan8, but very
different from the prevalence in Western countries, which suggests the
importance of ethnicity in RAHs development 7. These
lesions can be found concomitantly. Zhang et al found more than one type
of RAH in 17.4% of the TS patients7.
Pichi et al proposed a new classification of RAHs based on OCT findings:
type I, flat lesion within the RNFL without retinal traction; type II,
mildly elevated hyperreflective lesion (height <500 μm) with
retinal traction and internal retinal disorganization; type III,
elevated retinal mass (height >500 μm) mushroom shaped,
with internal retinal calcification with “moth-eaten” appearance; type
IV, elevated (height >500 μm) dome-shaped, non-calcified
retinal mass with optically empty cavity9.
Mutolo et al proposed a new subcategory of hamartomas (Type IIb), in
addition to type Iia lesions, described by Pichi et al as type II. Type
Iib lesions were characterized by an elevated retinal mass
(>500 μm) above the RNFL with or without retinal adhesion
or traction on the tumor surface, associated with a heterogeneous
intratumoral appearance, which could vary from a full appearance to the
presence of tumors to the presence of intralesional little empty spaces
or cysts, and to the existence of segmented vascular calcifications;
inner retinal layer, outer retinal layer, and full retinal thickness can
be involved with or without posterior optical
shadowing4.
In our report, it was possible to observe 4 different spectra of lesions
in the OCT. According to Pichi et al9, lesions can be
classified into type I (lesion 4), type II – Iia in Mutolo et
al4 classification – and type III (lesions 2 and 3,
respectively). An injury does not fit this classification (lesion 1).
Lesion 1 has type Iia features, but has a maximum thickness
<500 μm. Another difficulty for classification was the
involvement of the retinal layers. Even though lesion 2 was classified
as Iia, it has a different involvement of the retinal layers when
compared to lesion 1 – also classified as Iia. The difficulty found in
this classification was also reported by Kato et al and Mutolo et al,
which reinforces the need for more descriptive studies of OCT
aspects4,10.
Zhang et al showed that more than half of type 1 RAHs are located in the
temporal retina, often near the end of the arcades7.
In our report, 66.6% of the lesions in the right eye and 100% of the
lesions in the left eye were in the temporal region. However, calcified
RAHs – especially type 2 – are more commonly found in the
peripapillary region. The observation of greater retinal vascular
diameters in the temporal retina, indicating a greater blood supply when
compared to the nasal one, may explain the higher incidence of RAHs in
this
region7,11.
Demonstration of the microstructure of RAHs using OCT is not only useful
for detecting small or semi-transparent lesions that are easy to miss on
examination, but also facilitates the differentiation of RAH from
retinoblastoma, combined retinal hamartoma, and choroidal
tumors1,6. Furthermore, some authors have suggested
that, over time, translucent tumors may evolve into multinodular lesions
that have undergone cystic, hyaline or calcified changes, as if type 2
tumors represent a late stage of the lesions12, so,
OCT may also facilitate the follow-up of lesions4,12.
Conclusion:
This study described 4 different spectra of hamartomas using OCT-SS,
which allowed a deeper evaluation of the lesions. Hamartomas initially
compromise the inner retina layers with progression to the outer layers
as they grow and calcify. OCT is a non-invasive method which assists the
diagnosis of subclinical lesions and clinical characterization of
patients with TS. More descriptive studies of OCT aspects are needed to
better classify retinal hamartomas, due to their high prevalence in
patients with TS.