Development of an Anti-Elicitin Antibody-Based Immunohistochemical Assay for Diagnosis of Pythiosis.

Pythiosis is an emerging and life-threatening infectious disease of humans and animals living in tropical and subtropical countries and is caused by the fungus-like organism Pythium insidiosum. Antifungals are ineffective against this pathogen. Most patients undergo surgical removal of the infected organ, and many die from advanced infections. Early and accurate diagnosis leads to prompt management and promotes better prognosis for affected patients. Immunohistochemical assays (IHCs) have been developed using rabbit antibodies raised against P. insidiosum crude extract, i.e., culture filtrate antigen (CFA), for the histodiagnosis of pythiosis, but cross-reactivity with pathogenic fungi compromises the diagnostic performance of the IHC. Therefore, there is a need to improve detection specificity. Recently, the elicitin protein, ELI025, was identified in P. insidiosum, but it was not identified in other human pathogens, including true fungi. The ELI025-encoding gene was successfully cloned and expressed as a recombinant protein in Escherichia coli. This study aims to develop a new IHC using the rabbit anti-ELI025 antibody (anti-ELI) and to compare its performance with the previously reported anti-CFA-based IHC. Thirty-eight P. insidiosum histological sections stained positive by anti-ELI-based and anti-CFA-based IHCs indicating 100% detection sensitivity for the two assays. The anti-ELI antibody stained negative for all 49 negative-control sections indicating 100% detection specificity. In contrast, the anti-CFA antibody stained positive for one of the 49 negative controls (a slide prepared from Fusarium-infected tissue) indicating 98% detection specificity. In conclusion, the anti-ELI based IHC is sensitive and specific for the histodiagnosis of pythiosis and is an improvement over the anti-CFA-based assay.

Prevalence and clinicopathologic findings of conjunctival epithelial neoplasia in pterygia.

PURPOSE: To study the prevalence of conjunctival neoplasia in clinically diagnosed pterygia and the clinicopathologic characteristics of conjunctival tissues obtained from pterygium excision. DESIGN: Prospective, observational case series. PARTICIPANTS: From February through August 2007, consecutive subjects indicated for pterygium excision were enrolled from an outpatient eye clinic of King Chulalongkorn Memorial Hospital, Bangkok, Thailand, and from the eye camp at the 6th Station of the Thai Red Cross Society, Aranyaprathet District, Sa Kaeo, Thailand. A total of 498 eyes from 482 subjects were studied. The mean age of the subjects was 56.5 ± 11.7 years. The male-to-female ratio was 3:7. METHODS: Clinical data were gathered, including age, sex, occupation, family history, and medical history. Pterygia were clinically graded as mild, intermediate, or fleshy. Tissues from surgical fields were fixed in formalin and processed using standard pathology laboratory methods. MAIN OUTCOME MEASURES: Histopathologic results were examined in a masked fashion by 3 pathologists. RESULTS: Ninety-one percent of tissue was from primary pterygia. Most lesions were classified as intermediate grade (45.2%). Histopathologic results showed that 4 eyes had conjunctival intraepithelial neoplasia. Two eyes had minimal cellular atypia at the conjunctival epithelium. Two eyes had complex choristoma. For the subjects who had conjunctival epithelial neoplasia, the mean age was 57.0 ± 8.0 years, 44.4% were male, and none had a history of carcinoma in other organs or any history of herpes virus, human papilloma virus, or human immunodeficiency virus infections. CONCLUSIONS: The prevalence of conjunctival epithelial neoplasia in clinically diagnosed pterygia is approximately 1.8%. Because the clinical characteristics of subjects who have conjunctival epithelial neoplasia apparently did not differ from those without, tissue pathologic examination may be required to diagnose the condition.

Case Report: An Eyelid Nodule Caused by Candidatus Dirofilaria hongkongensis Diagnosed by Mitochondrial 12S rRNA Sequence.

A 59-year-old female living in Rayong Province, eastern Thailand, presented with painless, right upper eyelid nodule for 3 months. Upon removal of the eyelid mass, a well-circumscribed, firm globular mass with diameter about 1 cm was found. Histopathological examination revealed an immature female dirofilarial worm reminiscent of Dirofilaria repens, characterized by prominent sharp longitudinal ridges at external surface of the cuticle. Analysis of the mitochondrial 12S rRNA sequence showed that the worm belongs to Candidatus Dirofilaria hongkongensis. It is likely that some infections previously reported as D. repens based on histological examination may have actually been due to Candidatus D. hongkongensis.

Evaluation of an in-house immunoperoxidase staining assay for histodiagnosis of human pythiosis.

Pythiosis, a life-threatening infectious disease of humans and animals in tropical and subtropical countries, is caused by the fungus-like organism Pythium insidiosum. As diagnosis of pythiosis is difficult, delayed diagnosis of pythiosis leads to poor prognosis. We developed an immunoperoxidase staining assay using rabbit anti-P. insidiosum antibodies to detect P. insidiosum directly in infected tissues of 19 patients with vascular (n = 11), ocular (n = 7) or cutaneous (n = 1) pythiosis. Tissue sections from 31 patients with various fungal infections were included as controls. Tissue sections from all pythiosis patients and 2 patients with Fusarium infections were stained positive, whereas the other 29 control sections were stained negative. Sensitivity and specificity of the assay was 100% and 94%, respectively. Based on the prevalence of human pythiosis (2%), calculated positive predictive value and negative predictive value was 24% and 100%, respectively. Thus, the diagnostic value of this assay is for ruling out pythiosis. The assay requires routine laboratory equipments and can easily be performed by pathologists in rural hospitals where the disease is more prevalent.

Paraurethral leiomyoma: a case report.

A paraurethral leiomyoma is a rare benign hormone-dependent tumor of mesenchymal origin. A 43-year-old woman presented with a palpable mass near the urethral opening with no abnormal urinary symptom. Simple excision was performed Histopathological diagnosis was paraurethral leiomyoma with confirmation by immunohistochemical study. Further hormonal study of the tumor yielded positive estrogen and progesterone receptor expression, suggesting conservative treatment with gonadotropin-releasing hormone (GnRH) agonist or antagonist may have a role as an alternative treatment in an inoperable case.

Xanthogranulomatous adrenalitis in a neonate: CT and US findings.

We report a 46-day-old female infant with xanthogranulomatous adrenalitis. Ultrasonography showed a complex, solid-cystic right suprarenal mass with poorly defined margins. Colour flow Doppler revealed the solid portion of the mass to be vascular. CT demonstrated a heterogeneous cystic and solid mass with some contrast enhancement in the inferior part of the lesion. There was compression of the adjacent upper pole of the right kidney and the lateral aspect of the inferior vena cava. The mass was completely removed; histological examination revealed xanthogranulomatous adrenalitis. At the time of this report she remained well 3 years following surgery.