Ocular ultrasonography is an imaging technique considered essential for accurately diagnosing and following up on a variety of intraocular tumors.
32,33 In recent years, two ultrasonographic observations, nevi thickness >2 mm and acoustic hollowness, were shown to be predictive factors for uveal nevi growth and indirect malignant transformation.
8 Obviously, nevi thickness is a clinical observation directly related to the growth of a tumor.
34 On the other hand, acoustic hollowness is a characteristic ultrasonographic observation in UM.
33 This finding is related to the resultant ultrasound beam attenuation of the homogeneous and dense histology of these types of tumors. This type of attenuation is seen in B-mode echograms as hypoechogenic areas that are normally located near the base of the tumor and in A-mode ultrasonography as a progressive diminution in the ultrasonographic signal (kappa angle).
35 Both thickness estimation and occurrence of acoustic hollowness are typical clinical signs often studied in standard clinical protocols for studying uveal nevi and UM.
36 Previous proteomics studies performed by our group identified, for the first time, the overexpression of the oncoprotein DJ-1/PARK7 in UM.
24,37 Furthermore, we discovered that the tumor mass was capable of secreting the soluble form of this protein both in vitro and in vivo, suggesting its potential use as an UM biomarker.
24,38 Accordingly, preliminary results from our studies analyzing tumor fragment secretomes revealed high concentrations of DJ-1. Paralleling this in vitro secretion, we also detected abundant levels of soluble DJ-1 in the same sera from these patients as well as strong immunoreactive staining of this protein in each tumor mass (unpublished results, 2011). Furthermore, increased levels of DJ-1 were observed in several other types of tumors
39,40 ; however, its secretion into the circulation was described only in breast cancer patients. In that study, DJ-1 protein was detected at high levels in the sera of only 37% patients with new diagnoses.
41 Therefore, in the present work, we chose to exclude patients with any other disease type previously associated with DJ-1. It is well documented that DJ-1 is implicated in a variety of conditions, such as Parkinson's disease, infertility, ischemic injury, and amyotrophic lateral sclerosis.
18,19,42 Although there is no information associating DJ-1 and cutaneous melanoma, we decided to exclude patients with any suspicious cutaneous melanocytic lesions. It is well known that some cases of uveal nevi are associated with dysplastic nevi of the skin.
43