Conjunctival stromal tumour (COST): anterior-segment OCT findings.

Conjunctival stromal tumour (COST) is a recently described rare conjunctival tumour of mesenchymal origin with only four publications describing a handful of cases thus far. In this report, we describe the anterior-segment optical coherence tomography (AS-OCT) characteristics in a case of COST for the first time, in addition to the clinical and histopathological characteristics. The AS-OCT showed an elevated, dome-shaped hyporeflective homogenous lesion in the conjunctival stroma lined by hyperreflective outer layer with mild posterior shadowing, consistent with histological description of a paucicellular tumour with large myxoid collagenous material inside. Immunohistochemistry showed positive CD34 and vimentin but negative S100 and smooth muscle actin, thereby differentiating it from conjunctival myxoma.

Non-invasive dynamic assessment of conjunctival melanomas by photoacoustic imaging.

This study describes non-invasive photoacoustic imaging to detect and monitor the growth of conjunctival melanomas in vivo. Conjunctival melanomas were induced by injection of melanotic B16F10 cells into the subconjunctival space in syngeneic albino C57BL/6 mice. Non-invasive in vivo photoacoustic tomography was performed before, and after tumor induction up to 2 weeks. Spectral unmixing was performed to determine the location and to assess the distribution of melanin. The melanin photoacoustic signal intensity was quantified from the tumor-bearing and control eyes at all timepoints. For postmortem validation, total tumor and melanotic tumor volumes were measured using H&E stained tumor sections and were compared to in vivo photoacoustic imaging measurements. Photoacoustic imaging non-invasively detected eyes bearing conjunctival tumors of varying sizes. The melanin signal was detected as early as immediately following injection of melanotic tumor cells. Changes in tumor size over time were assessed with changes in the volume and intensity of the melanin signal. Four growing tumors and one regressing tumor were observed. Three tumors without significant change in signal intensity over time were observed, showing variable growth. Photoacoustic melanin signal on the last day of in vivo imaging correlated with postmortem total tumor volume (R2 = 0.81) and melanotic tumor volume (R2 = 0.80). The results of our study show that actively growing conjunctival melanomas can be quantified in a non-invasive manner using in vivo photoacoustic tomography. The photoacoustic melanin signal intensity correlated with total and melanotic tumor volume. This novel in vivo imaging platform may help to assess new treatment modalities to manage ocular tumors.

Monte Carlo simulations applied to conjunctival lymphoma radiotherapy treatment.

INTRODUCTION: Small radiation fields are increasingly applied in clinical routine. In particular, they are necessary for the treatment of eye tumors. However, available treatment planning systems do not calculate the absorbed dose with the desired accuracy in the presence of small fields. Absorbed dose estimations obtained with Monte Carlo methods have the required accuracy for clinical applications, but the exceedingly long computation times associated with them hinder their routine use. In this article, a code for automatic Monte Carlo simulation of linacs and an application in the treatment of conjunctival lymphoma are presented. METHODS: Simulations of clinical linear accelerators were performed with the general-purpose radiation transport Monte Carlo code penelope. Accelerator geometry files, in electron mode, were generated with the program AutolinaC. RESULTS: The Monte Carlo simulation of an annular electron 6 MeV field used for the treatment of the conjunctival lymphoma yielded absorbed dose results statistically compatible with experimental measurements. In this simulation, 2% standard statistical uncertainty was reached in the same time employed by a hybrid Monte Carlo commercial code (eMC); however, eMC showed discrepancies of up to 7% on the absorbed dose with respect to experimental data. Results obtained with the analytic algorithm Pencil Beam Convolution differed from experimental data by 10% for this case. CONCLUSION: Owing to the systematic application of variance-reduction techniques, it is possible to accurately estimate the absorbed dose in patient images, using Monte Carlo methods, in times within clinical routine requirements. The program AutolinaC allows systematic use of these variance-reduction techniques within the code penelope.

20 MHz high frequency ultrasound assessment of scleral and intraocular conjunctival squamous cell carcinoma.

AIM: To assess in a prospective manner, high frequency ultrasound diagnosis of deep invasion by conjunctival squamous cell carcinoma. METHODS: Prospective, non-randomised case series comparing 20 MHz high frequency ultrasonographic and clinicopathological data. RESULTS: 20 MHz high frequency ultrasound delineated the degree of deep involvement of this tumour into the sclera, globe, and orbit. The results of ultrasonography correlated with the clinicopathological results. CONCLUSIONS: High frequency ultrasound is a useful diagnostic adjunctive test in patients with possible deep involvement by a conjunctival squamous cell carcinoma.