18-Fluorine-labelled 2-deoxy-2-fluoro-D-glucose positron emission tomography/computed tomography standardised uptake values: a non-invasive biomarker for the risk of metastasis from choroidal melanoma.

AIMS: To correlate the clinical, ultrasound and pathological features of the eyes first evaluated by 18-fluorine-labelled 2-deoxy-2-fluoro-d-glucose (FDG) positron emission tomography (PET)/computed tomography and then enucleated for choroidal melanoma. METHODS: 14 consecutive patients enucleated for choroidal melanoma were examined. At presentation, clinical, ultrasound and PET/computed tomography imaging were carried out. Ultrasound was used to measure the tumour size and evaluate the tumour shape and intrinsic vascularity (blood flow). Histopathological and immunohistochemical evaluations included tumour cell type, necrosis, glycogen content, vascularity and extrascleral extension. RESULTS: 13 tumours were T3 and one T2 (American Joint Committee on Cancer - International Union against Cancer). The mean tumour height was 10.6 (range 3.5-17.7) mm with a largest basal dimension of 19.3 (range 14.5-30) mm. Patients having melanoma with the highest six standardised uptake values ((SUV) > or =4.0) were (on average) >10 years older, their melanomas had larger basal dimensions and were epithelioid-cell type; three melanomas were centred anterior to the equator; three contained enlarged blood vessels (>150 mum in diameter); and three formed extrascleral extension. Patients with the two highest SUV tumours died due to metastatic melanoma. CONCLUSION: PET/computed tomography imaging offers a physiological assessment of glucose metabolism in primary choroidal melanomas. Increased FDG PET/computed tomography SUV was positively correlated with known clinical, pathological and ultrasound features linked to metastatic potential of choroidal melanoma.

Anterior chamber paracentesis cytology (cytospin technique) for the diagnosis of intraocular lymphoma.

AIM: To report on the diagnosis of intraocular lymphoma by aqueous cytology. METHODS: Four patients suspected of having intraocular lymphoma were evaluated by anterior chamber (AC) paracentesis with cytology (cytospin technique). All had a history of non-ocular lymphoma and presented with at least one plus anterior chamber cells despite intensive glucocorticoid therapy. A 25 gauge needle was inserted through clear cornea (bevel up), over the iris stroma, so as to drain the AC. The aqueous humour was sent for cytopathology (cytospin technique), culture, and sensitivity tests. RESULTS: All procedures were diagnostic. Three were lymphoma and the fourth was culture positive for Propionibacterium endophthalmitis. No secondary glaucoma, hyphaema, cataract or infections were related to AC paracentesis. CONCLUSIONS: In this series, AC aspiration cytology enhanced by the cytospin technique was an effective, minimally invasive alternative to vitrectomy based biopsy. This technique should be considered to rule in the diagnosis of intraocular lymphoma in selected cases with cells in the anterior chamber.

A simple method for fixation and microdissection of frozen fresh tissue sections for molecular cytogenetic analysis of cancers.

Microdissection has been widely used for procuring DNA from specific microscopic regions of formalin fixed, paraffin embedded tissue sections. We have developed a method for fixation and microdissection of frozen fresh biopsy tissue sections. Five micrometer frozen fresh tissue sections were fixed with ethanol and stored at room temperature. Well defined regions from hematoxylin and eosin (H & E) stained or unstained sections were briefly steamed and microdissected using a needle. The dissected tissue was digested with proteinase K and DNA was isolated. Whole genome amplifications were obtained by degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) from these samples. The reliability of this technique was demonstrated by comparing conventional comparative genomic hybridization (CGH) with DOP-PCR-CGH. The advantages of this method are that frozen fresh sections can be fixed easily and stored for more than 4 years, it is easy to microdissect and pick-up very minute regions (0.1 mm(2)), and it is rapid; microdissection and purification can be accomplished within 3 h. Using DNA from microdissected sections, DOP-PCR-CGH revealed genetic abnormalities more accurately than conventional CGH. Although this novel method was demonstrated using DOP-PCR-CGH, we believe that it will be useful for other genetic analyses of specific small regions and cell populations. We also observed whether storage time, H & E staining and crude DNA extracts affected the quality of amplified DNA. DNA integrity was maintained for at least 49 months in ethanol fixed sections that were stored at room temperature, but DNA was gradually degraded after one month if the ethanol fixed sections had been H & E stained and stored. When crude DNA extracts from H & E stained sections were used, the size of the DOP-PCR product was reduced. Our study suggests that ethanol fixed tissue sections may be stored at room temperature for at least 4 years without DNA degradation, the H & E stains may not affect the quality of amplified DNA, but H & E or other components in the staining process may reduce the size of DOP-PCR product, which is critical for the quality of CGH hybridization.