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A D Singh

Publications and source records attributed to A D Singh.

At least 37 records · Page 2Linked to original sources
PubMed2004

The Zimmerman-McLean-Foster hypothesis: 25 years later.

It is now 25 years since the publication of the landmark article by Zimmerman, McLean, and Foster, in which they cast doubts on the benefit of enucleation, which was the prevailing management of choroidal melanoma at that time. Over the past 25 years several advances have been made in the management of uveal melanoma. Research in the pathobiology of cancer metastasis in general and uveal melanoma in particular has also provided new insights. In this review, the Zimmerman-McLean-Foster hypothesis is explored in the light of current clinical, epidemiological, statistical, and experimental evidence.

Brachytherapy↗
PubMed2004

Photodynamic therapy of circumscribed choroidal haemangioma.

AIM: To evaluate efficacy of verteporfin ocular photodynamic therapy (PDT) in treatment of 10 patients with a symptomatic circumscribed choroidal haemangioma. DESIGN: Prospective non-randomised, interventional case series and critical review of previously published studies. METHODS: 10 consecutive patients (seven primary, two failed transpupillary thermotherapy (TTT), and one failed external beam radiotherapy) with symptomatic circumscribed choroidal haemangioma were treated using verteporfin 6 mg/m2 given as an intravenous infusion over 10 minutes. Diode laser (690 nm) with an intensity of 600 mW/cm2 for 83 seconds (50 J/cm2) was applied 5 minutes after completion of infusion. Single or multiple partially overlapping spots were applied based on the tumour basal dimensions. Periodic follow up with ophthalmoscopy, ultrasonography, and angiographic studies was performed. RESULTS: All 10 patients showed evidence of regression with flattening of tumour, resolution of subretinal fluid, and reduction of choroidal vasculature on angiograms. The visual acuity either improved or remained stable in eight (80%) patients. Visual loss due to delayed choroidal atrophy was seen in two patients. CONCLUSIONS: Although verteporfin PDT is an effective treatment for management of symptomatic circumscribed choroidal haemangioma, delayed treatment related effects can lead to visual loss.

Adult↗
PubMed2003

Gene expression profiling identifies tumour markers potentially playing a role in uveal melanoma development.

Microarray is a powerful tool to compare the gene expression of different tumour specimens and cell lines simultaneously and quantitatively. To get a better insight into genes that are involved in uveal melanoma tumorigenesis, we compared the gene expression profiles of 12 different uveal melanoma cell lines with three melanocyte cell cultures obtained from healthy donor eyes. Gene expression profiles were obtained by nylon filter arrays, containing 1176 gene spots related to cancer development. The expression levels of selected genes were validated on cell lines and primary uveal melanomas by real time RT-PCR, and were subsequently included in cluster analysis. Four candidate tumour markers, Laminin Receptor 1, Endothelin 2, Von Hippel Lindau Binding protein 1 and Cullin 2, have been selected from genes that were differentially expressed in the uveal melanoma cell lines compared to the normal uveal melanocytes. In primary uveal melanomas, these four markers could discriminate between two classes of uveal melanoma, which may be indicative of a differential disease process.

Biomarkers, Tumor↗
PubMed2001

Adenocarcinoma arising from congenital hypertrophy of retinal pigment epithelium.

Congenital hypertrophy of the retinal pigment epithelium (CHRPE), traditionally regarded as a benign stationary condition, has recently been shown in 5 cases to give rise to an elevated, solid tumor. However, the histopathologic nature of the tumor that arises from CHRPE has not been previously determined. A 65-year-old woman developed a progressively enlarging peripheral fundus tumor that arose from a focus of classic CHRPE. The tumor produced a localized exudative retinal detachment, cystoid macular edema, and surface-wrinkling retinopathy. The mass was removed by local resection, and histopathologic examination revealed a low-grade adenocarcinoma of the retinal pigment epithelium, apparently arising from CHRPE. Although CHRPE is usually a benign nonprogressive lesion, it can give rise to a malignant tumor. Congenital hypertrophy of the retinal pigment epithelium should be observed periodically for development of a neoplasm.

Adenocarcinoma↗
PubMed2001

Pigmented conjunctival squamous cell carcinoma simulating a conjunctival melanoma.

PURPOSE: To report a pigmented conjunctival squamous cell carcinoma that clinically simulated a conjunctival melanoma. DESIGN: Interventional case report. METHODS: Ocular examination, surgical excision, and clinicopathologic correlation. RESULTS: A 78-year-old white man developed a lightly pigmented mass at the temporal limbus of his right eye. The differential diagnosis included pigmented squamous cell carcinoma and malignant melanoma. Histopathologic examination revealed a malignant squamous cell tumor that contained foci of melanin pigment. The final diagnosis was pigmented conjunctival squamous cell carcinoma. CONCLUSION: Conjunctival squamous cell carcinoma may rarely be pigmented and simulate a conjunctival melanoma.

Aged↗
PubMed2001

Choroidal melanoma metastatic to the contralateral choroid.

PURPOSE: To report metastasis of choroidal melanoma to the contralateral choroid. METHODS: Interventional case report. In a 49-year-old Caucasian female, a primary choroidal melanoma, left eye, was diagnosed and treated with Ruthenium-106 plaque radiotherapy. The choroidal melanoma showed excellent regression with flattening of the mass and adjacent chorioretinal atrophy. RESULTS: Fifteen years after brachytherapy for choroidal melanoma, left eye, the patient developed a metastatic melanoma to the contralateral choroid as the first sign of metastasis. No history of oculo(dermal) melanocytosis or cutaneous melanoma existed. Systemic evaluation disclosed multiple metastases confined to the liver. CONCLUSION: Metastasis to the contralateral choroid can be the first sign of metastasis from choroidal melanoma.

Brachytherapy↗
PubMed2001

Iris melanoma: risk factors for metastasis in 169 consecutive patients.

OBJECTIVE: To identify risk factors that predict distant metastases of iris malignant melanoma. DESIGN: Retrospective case series. PARTICIPANTS: The participants included 169 consecutive patients with microscopically confirmed iris malignant melanoma managed on the Oncology Service at Wills Eye Hospital between 1974 and 1999. MAIN OUTCOME MEASURES: The main outcome measure was the development of distant tumor metastasis. Cox proportional regression models were used to calculate the risk of eventual metastatic spread. RESULTS: Of 1054 patients referred with suspicious iris melanocytic tumors (rule out malignant melanoma) over a 25-year period, 169 patients (16%) had microscopically proven iris melanoma, and the remainder (84%) had clinically diagnosed iris nevus. Of the patients with iris melanoma, the mean age at the time of diagnosis was 43 years (median, 45 years; range, 1-90 years). All patients were Caucasian. The mean tumor base was 6 mm (median, 5 mm; range, 1-17 mm), and mean tumor thickness was 2 mm (median, 2 mm; range, 1-4 mm). The mean number of clock hours of tumor involvement in the iris was four, tumor seeding on the iris was four, and tumor seeding into the anterior chamber angle was four. Extraocular extension was present in 10 eyes (6%). The tumor management consisted of local resection (iridectomy, iridocyclectomy, or iridocyclogoniectomy) in 102 patients (60%), enucleation in 51 (30%), plaque radiotherapy in 9 (5%), and observation in 7 patients (4%). Metastasis developed in nine patients (5%). Using Kaplan-Meier life table analysis, metastasis was found in 3% of patients at 5 years, 5% at 10 years, and 10% at 20 years. The clinical factors at initial evaluation predictive of eventual metastasis from iris melanoma included increasing age at diagnosis (P = 0.03), elevated intraocular pressure (P = 0.03), posterior tumor margin at angle or iris root (versus midzone) (P = 0.02), extraocular extension (P: = 0.02), and prior surgical treatment of the tumor elsewhere before referral (versus observation) (P = 0.006). The method of management (resection, radiotherapy, or enucleation) did not have an impact on metastasis. CONCLUSIONS: Microscopically confirmed iris melanoma demonstrates distant metastasis in 5% of patients at 10 years follow-up. Metastases are more likely to develop in those patients who are older and show tumor features of iris root/angle location with elevated intraocular pressure and extraocular extension.

Adolescent↗
PubMed2001

Retinal capillary hemangioma: a comparison of sporadic cases and cases associated with von Hippel-Lindau disease.

OBJECTIVE: To report observations regarding the onset of tumors in patients with retinal capillary hemangiomas (RCH) and comparing sporadic cases with those associated with von Hippel-Lindau (VHL) disease. DESIGN: Retrospective consecutive case series. PARTICIPANTS: Sixty-eight patients with RCH managed at a tertiary referral center. MAIN OUTCOME MEASURES: The data were analyzed for age at diagnosis of RCH, two-hit mutation model, onset of new tumors, and random (Poisson) distribution. RESULTS: Among 68 patients, we identified 174 RCHs in 86 eyes. Thirty-one patients had VHL disease, and 37 patients were sporadic. The median age at diagnosis in cases with VHL disease was 17.6 years (range, 2.8-46.7 years), and in those without VHL disease it was 36.1 years (range, 7.0-74 years). The age distribution of RCH followed a two-hit mutation model. In eyes with VHL disease, the total number of RCH were distributed randomly as calculated by the Poisson distribution (mean number of tumors = 4). Overall onset of 33 new tumors was documented in 11 eyes (13%) over a median interval of 16 months (range, 3-235 months). All new tumors developed before the age of 47 years. The retinal location of new tumors was similar to the previous tumors with most new tumors located in the superotemporal quadrant (42%) and in the midperipheral retina (58%). Of the 50 patients initially manifesting solitary RCH, only 4 had new tumors develop over a median follow-up duration of 6.4 years (range, 0-33 years). All four cases had VHL disease. CONCLUSIONS: The median age at diagnosis of RCH in patients with VHL disease was almost 18 years less than those without VHL disease. The age distribution of RCH followed the two-hit mutation model. In VHL disease, the number of RCH is determined randomly. Most of the new RCH develop by the age of 47 years. In the absence of VHL disease, it is unlikely for patients with solitary RCH to develop new tumors.

Adolescent↗
PubMed2001

Plaque radiotherapy for retinoblastoma: long-term tumor control and treatment complications in 208 tumors.

OBJECTIVE: To evaluate the clinical factors predictive for tumor recurrence and treatment complications in a large series of children who underwent plaque radiotherapy for retinoblastoma. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: The participants included 141 children with retinoblastoma who were managed on the Oncology Service at Wills Eye Hospital with plaque radiotherapy between July 1976 and June 1999. MAIN OUTCOME MEASURES: Tumor recurrence and treatment complications. RESULTS: There were 208 tumors managed with plaque radiotherapy. The mean patient age at plaque treatment was 19 months. Prior treatment to the retinoblastoma of concern was delivered to 148 tumors (71%) and included various combinations of treatments such as intravenous chemoreduction, external beam radiotherapy, laser photocoagulation, thermotherapy, and cryotherapy. For 72 retinoblastomas (35%), more than one therapeutic method had failed to achieve tumor control before the use of plaque radiotherapy. Of the 208 retinoblastomas managed with plaque radiotherapy, Kaplan-Meier estimates of tumor control were 83% at 1 year and 79% at 5 years. Of the 60 tumors treated only with plaque radiotherapy (primary treatment), recurrence at 1 year was 12%. Of the 148 tumors treated after failure of other methods (secondary treatment), specific Kaplan-Meier estimates of tumor recurrence at 1 year was detected in 8% of tumors previously treated with chemoreduction, 25% of tumors previously treated with external beam radiotherapy, 34% tumors previously treated with both chemoreduction and external beam radiotherapy, and 8% of tumors previously treated with laser photocoagulation, thermotherapy, or cryotherapy (methods other than chemoreduction and external beam radiotherapy). Using multivariable analysis, the risks for tumor recurrence included the presence of tumor seeds in the vitreous, presence of subretinal tumor seeds, and increasing patient age. Using Kaplan-Meier estimates, radiation complications at 5 years of follow-up included nonproliferative retinopathy in 27%, proliferative retinopathy in 15%, maculopathy in 25%, papillopathy in 26%, cataract in 31%, glaucoma in 11%, and scleral necrosis in 0%. CONCLUSIONS: Plaque radiotherapy for retinoblastoma provides tumor control in 79% of cases at 5 years of follow-up. It is particularly useful for those tumors that fail treatment with chemoreduction, laser photocoagulation, thermotherapy, and cryotherapy. Tumors in young patients without vitreous or subretinal seeding show the best long-term control.

Brachytherapy↗