Acute histoplasmosis choroiditis in 2 immunocompetent brothers

Multimodal imaging of an acute presentation of ocular histoplasmosis syndrome in an immunocompetent patient

Purpose

Presumed ocular histoplasmosis syndrome (POHS) is a posterior segment disorder that is usually subclinical unless choroidal neovascular membrane (CNVM) develops. It is thought to be the sequela of a prior systemic infection with Histoplasma capsulatum, and evidence supporting this association is based on epidemiologic, animal, and few enucleation studies. Acute presentation of chorioretinal involvement during an initial histoplasmosis systemic infection in immunocompetent patients is rarely reported, presumably due to the usual lack of or minimal symptoms of both the systemic and ocular disease. We report on an immunocompetent male with choroidal lesions detected during disseminated histoplasmosis infection and characterize the lesions using multimodal imaging.

Observations

A 17-year-old male presented when routine optometry screening detected two deep, yellowish-white lesions in the left fundus. Optical coherence tomography (OCT) imaging confirmed a choroidal mass with extension through Bruch's membrane into the subretinal space and a small amount of subretinal fluid. Fluorescein angiography was suggestive of CNVM. There were no clinical findings of intraocular inflammation, and the patient was initially lost to follow-up. Eight weeks after last follow-up, the patient presented to the emergency department with fatigue, mild respiratory symptoms, and abdominal pain for the last month. Imaging revealed a mediastinal mass with hilar extension and innumerable nodules throughout the lung and spleen. Serum Histoplasma IgM/IgG were positive, and biopsy of the mediastinal mass revealed Histoplasma organisms. The patient was treated with antifungals and discharged. The patient underwent an extensive immunologic evaluation while admitted, which did not reveal an underlying immunodeficiency. On last follow-up, the choroidal lesions were smaller and more consolidated, and the subretinal fluid had resolved.

Conclusions and Importance

We present a patient with choroidal lesions in the setting of disseminated systemic histoplasmosis infection and characterize a lesion using multimodal imaging. The presentation of acute chorioretinal lesions in the setting of biopsy proven systemic Histoplasma infection supports H. capsulatum as the etiology of POHS.

Acute systemic histoplasmosis associated with chorioretinitis in an immunocompetent adolescent

Histoplasmosis is an endemic, systemic mycosis caused by the dimorphic fungus Histoplasma capsulatum. A minority of patients develop asymptomatic chorioretinitis known as presumed ocular histoplasmosis syndrome (POHS), which is typically associated with chorioretinal scarring and peripapillary atrophy and occasionally with choroidal neovascularization secondary to maculopathy. We report a case of acute severe bilateral chorioretinitis associated with disseminated H. capsulatum in an immunocompetent adolescent boy living in an endemic area. The chorioretinitis did not respond to systemic antifungal therapy, but both his systemic illness and ocular lesions resolved with the addition of systemic steroids.

Preventing reactivation of ocular histoplasmosis: Guidance for patients at risk

BACKGROUND

Ocular histoplasmosis syndrome (OHS), a significant cause of vision loss in young and middle-aged adults, is associated with the fungus Histoplasma capsulatum (Hc). There is considerable evidence that recurrent reactivation of perimacular ocular histoplasmosis lesions is an important cause of disease progression and that vision loss is at least, in part, a consequence of host sensitivity to fungal antigen.

METHODS

The etiology and pathogenesis of OHS is reviewed and specific recommendations are made for patients with OHS that may decrease the risk of reactivation of ocular histoplasmosis lesions and slow disease progression.

CONCLUSION

Patients with perimacular chorioretinal scars secondary to OHS should be informed by the clinician that they are at risk for vision loss; they should be told the symptoms of choroidal neovascularization and how to self-monitor their vision with an Amsler grid. We recommend they also be instructed on how to decrease their risk of reinfection by Hc. Aggressive treatment of dermatomycoses, onychomycosis, vaginal candidiasis, and other chronic fungal infections may decrease the risk of reactivation of ocular lesions. Patients with OHS who are considering LASIK surgery should be informed that the procedure may trigger choroidal neovascularization.

Current perspectives on ophthalmic mycoses

Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.

Association of the HLA-DR15/HLA-DQ6 haplotype with development of choroidal neovascular lesions in presumed ocular histoplasmosis syndrome

Associations of human leukocyte antigen DR2 (HLA-DR2) and HLA-B7 with presumed ocular histoplasmosis syndrome (POHS) in the United States has been previously described. However, these associations were determined by means of low-resolution, complement-dependent cytotoxicity assays for HLA-A, HLA-B, and HLA-DR molecules. To determine whether POHS is associated with other HLA alleles within the HLA-A, HLA-B, HLA-DR, and HLA-DQ loci, we performed a case control study of 34 patients diagnosed with macular choroidal neovascular membrane secondary to POHS and 45 healthy control individuals. Peripheral blood-derived DNA from the study patients was typed for HLA genes by means of sequence-specific primers that gave low-medium allele resolution. Significant associations were observed between HLA-B7 (X2 = 14.30, pc = 0.004, relative risk = 8.23), HLA-DR15 (X2 = 29.08, pc = 0.000001, relative risk = 27.50), and HLA-DQ6 (X2 = 23.09, pc = 0.00001, relative risk = 27.43) and POHS. Because there are strong linkage disequilibria between HLA-DR15 (a subtype of HLA-DR2) and HLA-B7 as well as HLA-DQ6, the significantly higher association of HLA-DR15 and HLA-DQ6 with POHS as compared to HLA-B7 suggests that the former alleles mediate susceptibility to the disease. In conclusion, there is a significant association between the HLA-DR15/HLA-DQ6 haplotype and development of choroidal neovascular lesions in POHS.

Fungal and parasitic infections of the eye

The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.

Fungal and parasitic infections of the eye

The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.

Aetiological study of the presumed ocular histoplasmosis syndrome in the Netherlands

AIM

To investigate whether presumed ocular histoplasmosis syndrome in the Netherlands is caused by Histoplasma capsulatum and whether other risk factors might play a role in the pathogenesis of this syndrome.

METHODS

23 patients were clinically diagnosed as having presumed ocular histoplasmosis syndrome based on the following criteria: peripapillary atrophy, punched out lesions, a macular disciform lesion or scar in one eye without vitritis. As controls, 66 sex and age matched healthy volunteers were used. Serum samples from both patients and controls were tested for the presence of antibodies against H capsulatum, Toxoplasma gondii, Toxocara canis et cati, Ascaris sp, and for the presence of antigens of Cryptococcus neoformans. Serum samples were also tested for the presence of autoantibodies against retinal or choroidal proteins. To investigate other risk factors, patients and controls were asked to fill in a health and travel related questionnaire. Ten patients with ocular toxoplasmosis were used as a disease control group.

RESULTS

None of the patients with presumed ocular histoplasmosis syndrome or controls had circulating antibodies directed against H capsulatum. No risk factors could be identified and no indications for autoimmunity and no evidence for the role of the other infectious agents could be demonstrated.

CONCLUSIONS

In a Dutch group of patients fulfilling the criteria of a disease currently named presumed ocular histoplasmosis syndrome, no risk factors or relation with the fungus H capsulatum could be detected.