Cytologic identification of Toxoplasma gondii from subretinal aspirate

Plentiful melanin pigment containing histiocyte-like cells in Coats disease: awareness avoids diagnostic pitfall

Coats disease is an exudative retinal vasculopathy characterized by presence of yellow-golden deposits in the retina and retinal detachment. Sub-retinal fluid drainage performed as a part of therapeutic management makes the fluid amenable to cytological examination. Infection by toxoplasma may closely simulate the ocular symptoms seen in Coats disease. Awareness of the cytological findings in Coats disease helps to clinch accurate diagnosis. We herein present a case of Coats disease with many histiocyte-like cells with plentiful intracytoplasmic melanin pigment in cytology smears from sub-retinal fluid where cytological diagnosis was challenging and a correct diagnosis was made with the aid of ancillary techniques.

Toxoplasma gondii bradyzoites and tachyzoites isolation from vitreous of atypical necrotizing retinitis

BACKGROUND

Detection of Toxoplasma gondii cysts in vitreous of immunocompetent patient with necrotizing retinitis is extremely rare. We herein report the isolation of Toxoplasma bradyzoites and tachyzoites from the vitreous of healthy person.

RESULTS

A 19-year-old immunocompetent female presented with sudden loss of vision in left eye since 1 week. The BCVA was 6/6 and HM in right and left eye. The left eye finding was suggestive of diffuse necrotizing retinitis with retinal detachment. The IgM and IgG for TORCH infection were negative and HIV, HCV and HBsAg tests were also non reactive. The patient underwent diagnostic and therapeutic vitrectomy with silicon oil installation. The vitreous toxoplasma IgG titre was found to be significantly raised to 1:16. Bradyzoites of toxoplasma were identified in H&E staining and tachyzoites of Toxoplasma were identified in Giemsa staining of vitreous sample. She received oral clindamycin and oral corticosteroid but the vision could not be restored in left eye.

CONCLUSION

Hence, atypical toxoplasmosis with necrotizing retinitis is a fulminant condition with the diagnostic and therapeutic challenge.

Interleukin-6 gene polymorphism (-174 G/C) is associated with toxoplasmic retinochoroiditis

PURPOSE

Experimental data have demonstrated a relevant role for IL-6 in the modulation of acute ocular toxoplasmosis. Therefore, we aim to investigate the possible association between the IL-6 gene polymorphism at position -174 and toxoplasmic retinochoroiditis (TR) in humans.

METHODS

Ninety-seven patients with diagnosed TR were recruited from the Uveitis Section, Federal University of Minas Gerais. For comparison, 83 healthy blood donors with positive serology for toxoplasmosis and without retinal signs of previous TR were included in the study. Genomic DNA was obtained from oral swabs of individuals and amplified using polymerase chain reaction (PCR) with specific primers flanking the locus -174 of IL-6 (-174G/C). PCR products were submitted to restriction endonuclease digestion and analysed by polyacrylamide gel electrophoresis to distinguish allele G and C of the IL-6 gene, allowing the detection of the polymorphism and determination of genotypes.

RESULTS

There was a significant difference in the genotype (χ(2) = 12.9, p = 0.001) and allele (χ(2) = 6.62, p = 0.01) distribution between TR patients and control subjects. In a subgroup analysis, there was no significant difference in genotypes and allele frequencies regarding TR recurrence.

CONCLUSIONS

This study suggests that the genotypes related with a lower production of IL-6 may be associated with the occurrence of TR.