Tyrosinase and nestin immunohistochemical expression in melanocytic nevi as a histopathologic pattern to trace melanocyte differentiation and nevogenesis.

While histological analysis represents a powerful tool for the classification of melanocytic lesions as benign or malignant, a clear-cut distinction between a nevus and a melanoma is sometimes a challenging step of the diagnostic process. The immunohistochemical detection of tyrosinase, cardinal melanogenic enzyme during melanocytic maturation, has often been helpful in formulating a differential diagnosis due to the peculiar staining pattern in nevocytes compared with melanoma cells. Tyrosinase distribution in nevi appears to overlap with the cytoarchitectural changes observable within these lesions, that result in epidermal or superficial dermal nevocytes being larger and strongly expressing melanocytic differentiation antigens, such as tyrosinase, compared with deeper dermal nevus cells. Our study aimed to evaluate the immunohistochemical expression pattern of tyrosinase in different histological types of acquired dysplastic melanocytic nevi, including junctional, compound, and intradermal nevi. Moreover, to estimate whether in nevocytes the expression of tyrosinase was associated with their differentiation state, we investigated the expression of two recognized markers of pluripotency, CD34 and nestin. In all examined nevi, our analysis revealed a remarkable immunoreactivity for tyrosinase in junctional and superficial dermal nevocytes and a decreasing gradient of staining in dermal nevocytes, up to become negative in deeper dermis. Meanwhile, junctional and dermal nevocytes were lacking in CD34 protein. Furthermore, nestin immunostaining showed an opposite distribution compared with tyrosinase, leading us to look into the tyrosinase/nestin expression pattern in melanocytic nevus as a tool to better understand the final stages of differentiation of melanocyte precursors toward their ultimate anatomical site into the epidermis.

Immunophenotypic characterization of telocyte-like cells in pterygium.

Purpose: Telocytes (TCs) are peculiar interstitial cells, characterized by their typical elongated and interconnected processes called telopodes. TCs are supposed to contribute to maintain tissue homeostasis but also to be involved in the pathophysiology of many disorders. The aim of the study was to identify TCs in pterygium, a chronic condition of bulbar conjunctiva, and to examine possible differences in TCs in terms of immunophenotype and/or localization between pterygium and normal conjunctiva, to evaluate the possible involvement of TCs in pathogenesis of pterygium. Methods: The analysis of the immunophenotype of TCs was performed on a group of 40 formalin-fixed and paraffin-embedded primary pterygium and ten bulbar conjunctiva samples. We examined with immunohistochemistry the expression of 11 commercially available antibodies (PDGFRα, CD34, c-kit, nestin, vimentin, α-SMA, laminin, S100, VEGF, CD133, and CD31) and with double immunofluorescence the concomitant expression of PDGFRα and CD34, and PDGFRα and nestin. In addition, we performed an ultrastructural study with transmission electron microscopy (TEM) on a group of five pterygium and three conjunctiva biopsy specimens. Results: TCs, ultrastructurally identified according to their "moniliform" prolongations, were localized underneath the epithelium along the basement membrane, around the vessels, and near the nerves and scattered in the stroma. In contrast, TCs, as fibroblasts, were almost absent in the fibrotic areas. In pterygium and normal conjunctiva, the TCs shared the same distribution pattern, except a marked TC hyperplasia detected in pterygium. Moreover, in pterygium, the immunohistochemical analysis of TCs showed a strong immunoreactivity to PDGFRα, CD34, and nestin. This result was confirmed with double immunofluorescence labeling, revealing that in pterygium stromal TCs always showed a PDGFRα+/nestin+ and PDGFRα+/CD34+ immunophenotype. Furthermore, moderate staining to vimentin and VEGF was detected, but only a small number of cells were weakly immunoreactive to laminin and S100. Only adventitial TCs of the perivascular sheaths exhibited strong immunoreactivity to α-SMA. Conversely, despite showing mild immunoreactivity to PDGFRα and CD34, the TCs in normal conjunctiva did not show any immunoreactivity to nestin and VEGF. Moreover, in pterygium and conjunctiva, the TCs were always negative for c-kit. Conclusions: Because of the distribution and immunophenotype, TCs in pterygium may represent a subpopulation of relatively immature cells with regenerative potential. In addition, the expression of nestin may suggest possible involvement of TCs as active players in the regeneration of ultraviolet-damaged stroma and vascular remodeling. The fibrotic transformation in the cicatricial area may stand for a breakdown of the regenerative process.

Role of epithelial-mesenchymal transition involved molecules in the progression of cutaneous melanoma.

Epithelial-mesenchymal transition (EMT) has been suggested to have a driving role in the acquisition of a metastatic potential by melanoma cells. Important hallmarks of EMT include both E-cadherin downregulation and increased expression of N-cadherin. This switch in distinct classes of adhesion molecules leads melanoma cells to lose contact with adjacent keratinocytes and interact instead with stromal fibroblasts and endothelial cells, thus promoting dermal and vascular melanoma invasion. Consequently, tumor cells migrate to distant host tissues and establish metastases. A key regulator in the induction of EMT in melanoma is the Notch1 signaling pathway that, when activated, is prompt to upregulate N-cadherin expression. By means of this strategy, melanoma cells gain enhanced survival, proliferation and invasion properties, driving the tumor toward a more aggressive phenotype. On the basis of these statements, the present study aimed to investigate the possible association between N-cadherin and Notch1 presence in primary cutaneous melanomas and lymph node metastases. Our results from immunohistochemical analysis confirmed a positive correlation between N-cadherin and Notch1 presence in the same tumor samples. Moreover, this study highlighted that a concomitant high expression of N-cadherin and Notch1, both in primary lesions and in lymph node metastases, predicts an adverse clinical outcome in melanoma patients. Therefore, N-cadherin and Notch1 co-presence can be monitored as a predictive factor in early- and advanced-stage melanomas and open additional therapeutic targets for the restraint of melanoma metastasis.

Vitamin D and vitamin D receptor in patients with ophthalmic pterygium.

Pterygium, an ultraviolet radiation (UV)-related disease, is a relatively benign process, but since it displays tumor-like features, it has been proposed to be a neoplastic- like growth disorder. Vitamin D performs a number of functions in addition to calcium homeostasis, as inhibition of cell proliferation, activation of apoptotic pathways, and inhibition of angiogenesis. Since the antitumor actions of vitamin D are mediated primarily through the nuclear vitamin D receptor (VDR), the aim of the present study was to investigate vitamin D status in patients with pterygium and in control subjects, and VDR immunohistochemical expression in samples of pterygium and normal conjunctiva in order to evaluate a possible role of vitamin D pathway in the pathogenesis of the disease. Serum vitamin D concentration was measured among 41 patients with pterygium and 47 volunteers by an automated chemiluminescence immunoassay. Moreover, 23 formalin- fixed and paraffin-embedded pterygium biopsy samples and 24 conjunctiva specimens were treated for the immunohistochemical demonstration of VDR using the streptavidin-biotin alkaline phosphatase method. No differences were observed about vitamin D level between patient with pterygium and control group, but significant differences between VDR immunolocalization in pterygium and normal conjunctiva were observed (P=0.00001). In conjunctiva, the immunoreactivity, localized mainly in cytoplasm of epithelial cells, may probably demonstrate VDR regulation of cell growth, differentiation, and apoptosis, while in pterygium VDR co-localization in the nucleus and cytoplasm of epithelial cells may indicate alternative nuclear pathways by which vitamin D might exert its antiinflammatory and anti-proliferative effects by the regulation of gene expression.

Activated Notch1 expression is associated with angiogenesis in cutaneous melanoma.

An early event in melanocytic tumor growth is the upregulation of Notch signaling. When an active form of Notch1 is overexpressed in primary human melanocytes, it increases cell growth, survival and invasive properties, promoting melanoma progression. Recent evidence suggested that tumor initiation and growth are driven by a subset of tumor-initiating cells termed cancer stem cells. Notch1 plays a predominant role in the maintenance of melanoblasts, including melanocyte stem cells, by preventing initiation of apoptosis. Moreover, the importance of Notch1 in the regulation of tumor angiogenesis is supported by growing evidence in various cancers. Nestin has been widely used as a marker for melanocyte stem cells as well as an angiogenic marker to evaluate neovascularity of endothelial cells in tumors. To gain an insight into the impact of Notch1 activation on the maintenance of melanocyte stem cells and angiogenesis in melanoma, the expression levels of activated Notch1 and nestin were analyzed by immunohistochemistry in 114 primary cutaneous melanomas and 35 lymph node metastases. Activated Notch1 and nestin expression was also evaluated in four dysplastic melanocytic nevi. This study provides evidence that activated Notch1 is overexpressed in cutaneous melanoma, in tumor cells as well as in microvessel endothelium, and that it can promote tumor angiogenesis. Indeed, the overexpression of activated Notch1 in both tumor and vascular endothelial cells was significantly associated with microvascular density in melanoma samples. Thus, activated Notch1 inhibitors may provide a therapeutic strategy in the treatment of melanoma by blocking tumor-associated vascularization.

Association between the ACE insertion/deletion polymorphism and pterygium in Sardinian patients: a population based case-control study.

OBJECTIVE: The purpose of the study was to examine whether the insertion (I) and/or deletion (D) polymorphism of ACE confers susceptibility to primary pterygium in Sardinian patients in a case-control study. METHODS AND RESULTS: Polymorphism genotyping was performed by nested PCR using genomic DNA extracted from the whole peripheral blood of participants with (n=251) and without (n=260) pterygium. DD, ID and II genotype frequencies were: 48%, 39% and 13%, respectively, for patients with pterygium, and 15%, 40% and 44%, respectively, for the control group. A statistically significant difference was found between the pterygium and control groups for the ACE I/D polymorphism (p<0.001). Moreover, a statistically significant difference was found between the DD and II groups (p<0.01; OR=10.49; 95% CI 6.18 to 17.79), DD+ID versus II group (p<0.01; OR=5.23; 95% CI 3.37 to 8.13) and DD versus ID groups (p<0.01; OR=3.21; 95% CI 2.04 to 5.04). CONCLUSIONS: Statistical analysis showed that the DD genotype is associated with an increased risk of developing pterygium, and with a good chance that the D allele may play an important role in the development of disease.

Nestin and vimentin colocalization affects the subcellular location of glucocorticoid receptor in cutaneous melanoma.

AIMS: Nestin (a neuronal stem cell/progenitor cell marker of central nervous system development), vimentin (which is ubiquitously expressed in mesenchymal cells), and the glucocorticoid receptor (GR, which is involved in the immune response, cell proliferation, and apoptosis) have been shown to interact in embryonic and undifferentiated tissues in modulating cell proliferation. The aim of this study was to analyse nestin, vimentin and GR expression in tumour tissue (melanoma), and their association with clinicopathological variables, to evaluate any effect on tumour progression. METHODS AND RESULTS: Immunohistochemistry, double-label immunofluorescence and confocal laser scanning microscopy were performed on biopsy specimens of cutaneous melanoma from 81 patients. Fisher's and Pearson's tests showed a correlation between nestin, vimentin and subcellular GR location (P = 0.008). Their concomitant expression also correlated with Clark level and thickness (P = 0.02 and P = 0.029, respectively). Kaplan-Meier analysis revealed a poorer outcome for stage III and IV patients with associated expression of nestin, vimentin and cytoplasmic GR in tumour tissue (P = 0.02). CONCLUSIONS: These results suggest the presence in melanoma of growth mechanisms involving nestin, vimentin, and GR, similarly to that occurring in embryonic and undifferentiated cells, and may help in understanding tumour biology to provide a molecular basis for clinical therapies.

Immunohistochemical analysis of angiotensin converting enzyme in Sardinian pterygium.

Pterygium is a common ocular surface disorder characterized by excessive cell proliferation, inflammation, fibrosis, angiogenesis and extracellular matrix remodeling. The Angiotensin converting enzyme (ACE or ACE I) is the major component of the Renin-angiotensin system (RAS) converting the inactive decapeptide Angiotensin I (Ang I) to the active octapeptide Angiotensin II (Ang II). Besides this 'classical role', it can act as transcriptional regulator in response to external stimuli that may lead to cell damage and tissue remodeling. Due to this role, it can be internalized into the nuclear compartment to act as transcriptional factor for proteins involved in the inflammatory response. The aim of the present study was to determine ACE expression and localization in pterygium and culture pterygium cells by immunohistochemistry. Our results are the first to demonstrate nuclear immunolocalization of ACE, more so in pterygium compared to conjunctiva epithelial cells in histological sections. ACE was not detected in the nuclei of subcultivated pterygium epithelial cells. The nuclear localization of ACE may be correlated with an anti-inflammatory path mediated by activation of its transcriptional role.

Erythropoietin is involved in angiogenesis in human primary melanoma.

In this study, the extent of angiogenesis, evaluated as microvascular volume density, immunoreactivity of tumour cells to erythropoietin (Epo) and of endothelial cells to Epo receptor (EpoR) have been correlated in human primary melanoma specimens. Results showed that Epo/EpoR expression correlate with angiogenesis and tumour thickness. These findings suggest that Epo is secreted by tumour cells and it affects vascular endothelial cells via its receptor and promotes angiogenesis in a paracrine manner, playing an important role in melanoma angiogenesis.

Nuclear 8-hydroxy-2'-deoxyguanosine as survival biomarker in patients with cutaneous melanoma.

8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the main mutagenic modifications induced in DNA by oxidative stress. Elevated levels of 8-OHdG have been regarded as an independent prognostic factor in different types of cancer. Various enzymes, such as human 8-oxoguanine DNA-glycosylase 1 (hOGG1) and glucose-6-phosphate dehydrogenase (G6PD), act as protection against oxidative stress. The low activity of such enzymes has been consistently associated with increased risk of progression in several tumor types. The aim of this study was to investigate whether 8-OHdG, hOGG1 and G6PD expression in tumor tissues might be a predictor of survival in melanoma patients. The expression of 8-OHdG, hOGG1 and G6PD was immunohistochemically investigated in primary cutaneous melanoma and the effect on survival was analyzed. Furthermore, the immunostaining for p53 and survivin was evaluated and the relationship among 8-OHdG, hOGG1, G6PD, p53 and survivin expression was analyzed. Kaplan-Meier analysis demonstrated that patients with low expression of nuclear 8-OHdG had significantly longer survival time compared with those with a high expression (P=0.032), whereas cancer-specific survival of patients was not associated with hOGG1 or G6PD expression. These results suggest an involvement of oxidative DNA damage in the process of melanoma pathogenesis and demonstrate that 8-OHdG expression in nuclei of tumor cells could be useful as an early independent prognostic marker in patients with primary cutaneous melanoma.

Nuclear factor-κB expression is predictive of overall survival in patients with cutaneous melanoma.

Nuclear factor (NF)- κB is one of the most important transcription factors that plays a crucial role in the regulation of a wide spectrum of genes involved in modulating the cell cycle, apoptosis, cell growth, angiogenesis, inflammation and the tissue invasiveness of highly malignant cells. NF-κB activity has been found to be constitutively elevated in a number of human tumors from either a haematological or solid origin, such as melanomas. In several studies, NF-κB activation was shown to be an adverse prognostic factor, and in melanoma it was proposed as an event that promotes tumor progression. This study aimed to evaluate whether NF-κB activation in tumor tissues, assessed by the expression of the NF-κB p65 subunit, has an effect on the survival of melanoma patients. The expression of NF-κB was immunohistochemically investigated, and the correlation with survival was analyzed. Furthermore, the immunostaining for p53 and survivin was evaluated, and the relationship of these apoptotic and anti-apoptotic factors with NF-κB expression was analyzed. Kaplan-Meier analysis showed that patients with low levels of NF-κB in the nuclei of tumor cells had a significantly longer survival compared to those with high levels. Multivariate analysis confirmed the predictive value of nuclear NF-κB, showing that its expression maintains significance after the model was adjusted using clinicopathological factors. The results demonstrate the correlation of NF-κB p65 nuclear staining with the disease-specific 5-year survival of melanoma patients and suggest that nuclear NF-κB p65 may be promising as an early independent prognostic factor in patients with primary cutaneous melanoma.

Long-term maintenance of prognostic value of survivin and its relationship with p53 in T4 breast cancer patients.

A large proportion of human tumors show deregulated expression of a variety of proteins that play a crucial role in the execution of the apoptotic program. Survivin belongs to the family of inhibitor of apoptosis proteins which were originally identified in baculoviruses. Ectopic expression of survivin conveys resistance to apoptosis to a variety of stimuli, and survivin is one of the most abundantly overexpressed genes in human tumors such as breast cancer. In this study we examined the expression of survivin protein in a series of T4 breast cancers to identify any correlation with long-term patient outcomes. Moreover, we investigated the hypothesis of a possible association between p53 and survivin as a factor further complicating the outcome. Archival specimens from 53 T4 breast cancer patients were included in the study and treated for the immunohistochemical localization of survivin and p53 using the streptavidin-biotin alkaline phosphatase method. The immunoreactivity was evaluated semiquantitatively according to the percentage of cells stained. Forty percent of tumors were positive for survivin. Statistical analysis revealed that survivin expression negatively influenced the 5- and 10-year disease-free and overall patient survival. In multivariate analysis, survivin expression was a significant independent prognostic indicator of worse outcome in overall survival [hazard ratio (HR)=2.61]. Our results showed that survivin is associated with a worse prognosis in patients with T4 breast cancer, and remarkably its prognostic relevance is maintained even long-term. Notably, p53 (HR=3.2) seems to negatively enhance the effect of survivin on survival.

The stem cell marker nestin predicts poor prognosis in human melanoma.

The cancer stem cell hypothesis suggests that mutated melanocyte stem cells are present in skin as precursors of melanoma cells. Nestin and CD133 have been described as markers of melanocytic stem cells. The aim of this study was to establish if melanocytic stem cells could have a prognostic significance in melanoma progression. An immunohistochemical study for nestin and CD133 was performed in 130 primary tumors and 32 nodal metastasis biopsy specimens to evaluate possible differences, and to compare the results with survival data and clinicopathological variables. Nestin was expressed in cytoplasm of non-pigmented tumor cells and in endothelial cells, especially at the invading tumor front. Nestin staining in stage I and II (according to the American Joint Committee on Cancer Staging system) melanoma patients significantly predicted poor survival (log-rank test, P=0.037), with lower survival rates in cases with nestin positivity in both tumoral and endothelial cells. CD133 staining was not associated with survival. There were no significant differences in nestin or CD133 expression between primary tumors and metastases. These results suggest that nestin expression in both tumoral and endothelial cells may be considered an important early prognostic marker in melanoma.

Correlation between NGF/TrkA and microvascular density in human pterygium.

Pterygium is a surface ocular lesion that is associated with chronic UV exposure. The primary effect is a solar actinic elastosis within the stroma. All the other changes are secondary. Pterygium is characterized by proliferation, inflammatory infiltrates, fibrosis, angiogenesis and extracellular matrix breakdown. The aim of this study was to correlate microvascular density and nerve growth factor (NGF)/NGF-receptor transmembrane tyrosine kinase (TrkA) expression in endothelial cells in human pterygium. Specimens of human pterygium obtained from 30 patients who had undergone surgical excision and of 10 normal bulbar conjunctiva were investigated immunohistochemically by using anti-CD31, anti-NGF and anti-TrkA antibodies. Results showed that endothelial cells in human pterygium are immunoreactive to both NGF and its receptor TrkA, and that this immunoreactivity is correlated to microvascular density. The results of this study suggest that an autocrine loop between NGF and its receptor TrkA is activated in pterygium and that it is involved in the angiogenic response taking place in this pathological condition. These data are in accord with recent evidences, which have clearly established that NGF plays a role as an angiogenic factor in several pathological conditions. Understanding the mechanism of angiogenesis in pterygium provides a basis for a rational approach to the development of anti-angiogenic therapy in patients affected by this disease.

Relationship between the expression of cyclooxygenase-2 and survivin in primary pterygium.

PURPOSE: To investigate the expression of cyclooxygenase-2 (COX-2) in a group of 93 Ecuadorian primary pterygia and to evaluate a possible association between COX-2 and survivin. METHODS: Primary pterygium samples were treated for the immunohistochemical evaluation of COX-2 and survivin. Mouse monoclonal antibody to COX-2 and rabbit polyclonal antibody to survivin were used. Statistical analysis was performed using the SPSS statistical software package, version 15.0. RESULTS: In our study, 63 (67.7%) primary pterygia samples were positive for COX-2 staining, and 70 (75.3%) specimens were positive for survivin expression. In the group of pterygia with survivin immunostaining, there were 55 (78.6%) samples with COX-2 expression. The staining of both COX-2 and survivin was localized in the lower and middle layers of the epithelium. When analyzed by Fisher's exact test, the expression of COX-2 showed a strong significant correlation with survivin (p=0.0002). CONCLUSIONS: These data, showing a significant correlation between COX-2 and survivin in primary pterygium, suggest that pterygium may originate through an anti-apoptotic mechanism.

Combinations of apoptosis and cell-cycle control biomarkers predict the outcome of human melanoma.

The deregulation of apoptosis is characteristic of human carcinogenesis. Survivin, an inhibitor of apoptosis, p53 and p16, two tumour suppressor proteins involved in cell cycle control, play a central role in apoptosis. The aim of this study was to investigate, in primary cutaneous melanoma from 68 patients, the expression of survivin with respect to p53 or p16; the association of these proteins, alone or in combination with clinicopathological features; and, most importantly, to elucidate the role of these markers in predicting survival. The level of survivin expression was significantly higher in the p53 positive group of melanomas compared with the p53 negative one, suggesting a cooperative effect in favouring the progression of melanoma, while no correlation was found between survivin and p16. Moreover, the altered expression of nuclear survivin, p53 and p16 were all associated with poor survival, as demonstrated by univariate analysis. However, these biomarkers have been shown to have superior predictive value when studied in combination (P<0.0001) rather than alone, while the risk of mortality grew progressively with increasing the number of altered biomarkers. These data suggest that the assessment of the combined marker status and number of altered markers in patients with melanoma provides important additional prognostic information that may help in patient selection for adjuvant therapies.

Oxidative stress in pterygium: relationship between p53 and 8-hydroxydeoxyguanosine.

PURPOSE: Ultraviolet (UV) radiation is known to cause oxidative DNA damage and is thought to be a major factor implicated in the pathogenesis of pterygium, a benign invasive lesion of the bulbar conjunctiva. Among all the photooxidative DNA products, 8-hydroxydeoxyguanosine (8-OHdG) is regarded as a sensitive and stable biomarker for evaluating the degree of DNA damage. The protein p53 is a major cell stress regulator that acts to integrate signals from a wide range of cellular stresses. UV radiation can cause mutations in the p53 tumor suppressor gene that, when inactivated through mutation and loss of heterozygosity, can lead to cell proliferation and genomic instability. In many types of UV-radiation damaged cells, p53 is overexpressed and immunohistochemically detectable. Recent data on tissues exposed to factors inducing oxidative stress have provided evidence of the concomitant presence of increased levels of 8-OHdG and protein p53. To verify a possible significant association between p53 and 8-OHdG, we examined a series of 31 Ecuadorian pterygia for the expression of the two markers. Moreover, we evaluated if clinical variables such as patient's age, gender, geographic location, and disease stage, might play a role affecting the 8-OHdG and p53 immunohistochemical staining results. METHODS: Primary pterygium samples were treated for immunohistochemical evaluations of 8-OHdG and p53 protein. Mouse monoclonal antibodies to 8-OHdG and p53 were used. Statistical analyses were performed using the SPSS 12 statistical software package. RESULTS: In our study, 21 (67.74%) pterygial samples were positive for 8-OHdG staining, 11 (35.48%) specimens were positive for p53 expression, and all negative control samples showed no staining. The staining for 8-OHdG was limited to the nuclei of the epithelial layer. No substantial staining was visible in the subepithelial fibrovascular layers. No differences in the pattern of staining between 8-OHdG and p53 were observed. All samples positive for p53 (11/31, 35.48%) were also positive for 8-OHdG immunostaining, and all specimens negative for 8-OHdG (10/31, 32.26%) were also negative for p53. When analyzed by Fisher's exact test, 8-OHdG expression was significantly associated with p53 positivity (p=0.0049). Student's t-test demonstrated statistically significant association between the expression of p53 and age (p=0.02). The correlation between the two markers and the other clinical variables revealed no statistically significant association. CONCLUSIONS: Although pterygium is a lesion with limited local invasion and an inability to metastasize, the concomitant presence of altered p53 in 8-OHdG-immunoreactive cells could provide evidence of apparent genetic instability, which is in contrast to its benign clinical course.

Photodynamic therapy of pterygium with verteporfin: a preliminary report.

OBJECTIVE: To assess the efficacy and safety of treating pterygia by photodynamic therapy (PDT) with verteporfin (Visudyne). MATERIALS AND METHODS: Ten consecutive patients with primary, recurrent, or secondary pterygium, refusing excisional surgery, were treated with a 689-nm laser delivered directly onto the pterygium after verteporfin infusion. Postoperative outcome was followed clinically and photographically for a minimum of 3 months. RESULTS: Successful photothrombosis of pterygium vascularization was obtained immediately after treatment in all cases. After 1 month, revascularization of pterygia was observed in 70% of cases, and treatment was repeated after a 3-month interval. Regression or stabilization of pterygia was manifested by a scarring reaction of the corneal apex with complete or partial disappearance of vascularity. No relevant side effects were observed in our series. CONCLUSION: PDT with verteporfin is a safe procedure to arrest the growth of pterygia. It is indicated for patients with a low- or medium-grade pterygium that refuse a surgical approach; however, multiple sessions may be required.