Oral histoplasmosis

Histoplasmosis is a systemic fungal disease that takes various clinical forms, among which oral lesions are rare. The disseminated form of the disease that usually occurs in association with Human Immunodeficiency Virus (HIV) is one of the AIDS-defining diseases. Isolated oral histoplasmosis, without systemic involvement, with underlying immunosuppression due to AIDS is very rare. We report one such case of isolated oral histoplasmosis in a HIV-infected patient.


INTRODUCTION
Histoplasmosis is a granulomatous systemic mycosis caused by the dimorphic fungus Histoplasma capsu latum, the clinical disease which was first described by Samuel Darling in 1905. Oral histoplasmosis usually occurs in association with the chronic disseminated form of the disease. Sometimes, they may present as the initial or the only mucocutaneous manifestation of the disease.

CASE REPORT
A 24-year-old female patient visited the Outpatient Department (OPD) of GITAM Dental College and Hospital, Visakhapatnam, with a chief complaint of painful ulcer in the posterior region in palate since 3 months.
Intraoral examination revealed a solitary ulcer of 3 × 2 cm on the posterior part of the soft palate, exten ding up to the pterygomandibular raphe (retromolar area) with raised and erythematous borders. The lesion was seen extending mesiodistally from the maxillary alve olar ridge 1 cm posterior to the 3rd molar, to 2 cm toward the midline and superioinferiorly from the posterior part of the palate to 3 cm inferiorly toward the pterygo-mandibular raphe (retromolar area) (Fig. 1).
A provisional diagnosis of chronic nonhealing ulcer was established. Excisional biopsy was performed preceded by incisional biopsy (Fig. 2).
Microscopic examination revealed typical sporangia, with collection of multinucleate giant cells along with eosinophilic necrosis. Macrophages with histoplasma bodies are also seen in the connective tissue (Figs 3 to 5). Special stains, like periodic acid schiff (PAS) stain and Grocott-Gomori methenamine silver (GMS) staining, were done to confirm the diagnosis (Figs 6 and 7).
Final diagnosis of histoplasmosis was confirmed after histopathological examination along with the ancillary special stains. Antifungal drugs were pres cribed    and patient is under follow-up for every 3 months (Fig. 8).

DISCUSSION
Oral ulcers are one of the most common complaints of the oral mucosa. Oral ulcers are determined by the underlying systemic condition, such as the nature, site, duration and frequency. Histopathological examination usually produces a definitive diagnosis for the majority of conditions. 1 Differential diagnosis for chronic nonhealing ulcers in the oral cavity, following lesions can be considered. 6 Fungal or mycotic infections are becoming more frequent because of expansion of at-risk population and use of treatment modalities that permit longer survival of these patients. 2 Candida species may be recovered from up to one-third of the mouths of normal individuals and are considered inhabitants of the normal flora of oral and gastrointestinal tract. Besides Candida spp., other fungi can also cause disease in humans. The mycotic infections can be superficial or deep fungal infections. Histoplasmosis is one of the deep fungal infection. 7 Histoplasmosis is caused by Histoplasma var capsula tum which is found worldwide in old buildings, soil rich in bird and bat droppings, endemic in Mississippi river valleys in the United States, Central and South America, Southern Europe, parts of Africa and Southeastern Asia. 2,3 However, in western and central regions of sub-Saharan Africa, the African clade of Histoplasma capsulatum, formerly named H. capsulatum var duboisii, can be found. 4,5 Histoplasma capsulatum is a dimorphic fungi, which exists as yeast at body temperature in the human host and as a mold in its natural environment. 4,11 Airborne spores of the organism are the main mode of transmission, which when inhaled pass into the terminal passages of the lungs and germinate.
The expression of disease depends on the quantity of spores inhaled and the immune status of the patient. Mild flu like illness is seen for 1 to 2 weeks. Then due to development of body immune function, they are ingested by macrophages. 4,11 There are different types of histoplasmosis like acute, chronic and disseminated histoplasmosis. 4,10 Disseminated histoplasmosis is characterized by the progressive spread of the infection to extrapulmonary sites, like spleen, adrenal glands, liver, lymph nodes, GIT, central nervous system, kidneys and oral mucosa. 4 Most commonly affected sites in oral cavity include tongue, palate and buccal mucosa. They present as a solitary, nonhealing painful ulcer with erythematous or irregular surface, with firm rolled margins indistinguishable from malignancy. 4 Microscopic examination of lesional tissue stained with hematoxylin and eosin (H&E) shows either a diffuse infiltrate of macrophages or more commonly collections of macrophages organized into granuloma, along with multinucleate giant cells is seen. The causative organism though identified with difficulty in H&E stain but the special stains, such as the PAS and GMS methods give better results. 4 Grocott-Gomori methenamine silver is preferred for screening, because it gives better contrast, and stains even degenerated and nonviable fungi that are sometimes refractory to the other stains, such as PAS and H&E.
The PAS stain performs almost as well as GMS in screening for fungi, it actually demonstrates fungal morphology. 12 Apart from clinical presentation and histopathology, they can also be diagnosed by cultures, serologic test, including compliment fixation test, immunodiffusion, direct immunofluorescence and histoplasmin skin test. 13 Treatment varies with each type of histoplasmosis like acute histoplasmosis, because it is a self-limited process, generally warrants no specific treatment other than supportive care with analgesics and antipyretics. 4 Chronic histoplasmosis, intravenous amphotericin B and itraconazole, can be used.
Disseminated histoplasmosis, amphotericin B, itraconazole or ketoconazole, can be used.
In addition, itraconazole is known to have rapid action and is effective in preventing a relapse. 4,13 CONCLUSION Dental clinicians play an important role in the diagnosis and management of oral fungal diseases. Therefore, an adequate knowledge about the possibility of systemic mycoses should be considered in cases of chronic oral ulcerations or unusual mouth lesions, particularly in the immunocompromised patients. Awareness of the characteristic signs and symptoms of oral fungal diseases might aid in early diagnosis, proper treatment and prevention of disease dissemination, thereby decreasing morbidity.