Conidiobolomycosis: A case report of rare fungal infection from the eastern India.

Conidiobolomycosis is a rare chronic subcutaneous mycosis of nose and paranasal sinuse predominately affects the middle age men in tropical countries. It is caused by a saprophytic fungus "Conodiobolus coronatus", which can survives in soils and dried vegetables for long period of time. C. coronatus belongs to the class Zygomycetes, order Entomophthorales. It is a fungus composed of thick- walled, short hyphae that grows at temperatures of 30 to 37 degrees C. Here we report a case of conidiobolomycosis in a 55- year- old farmer presented with a subcutaneous swelling over the left side of nose extending to left cheek.

INTRODUCTION

Conidiobolomycosis or a subcutaneous zygomycosis is a chronic subcutaneous fungal infection manifests as a painless swelling over the midline of the face of middle aged men in tropical countries like Africa and South-East Asia. It is caused by a saprophytic fungus named “Conodiobolus coronatus” or “Conidiobolus incongruus”[12] which can survive in soils and dried vegetables for long duration.[3] C. coronatus belongs to the class zygomycetes, order Entomophthorale.[3] Two genera of zygomycetes exist, “Basidiobolus” and “Conidiobolus”. In “Conidiobolus” infection the nasal mucosa below the inferior turbinate is predominantly affected and appears as an uniform nasal swelling forming a centrofacial deformitywhereas in “Basidiobolus” infection the limb and limb girdle are predominantly affected.[4] Basidiobolomycosis[56] is a subcutaneous fungal infection caused by “Basidiobolus ranarum” which develops following traumatic inoculation of the fungus under the skin of limb or limb girdle areas, mostly in the children. The causative fungus of all zygomycetes is thick walled, short hyphae that grow at temperature between 30 degrees C and 37degrees C.[1] We present here a similar case of Conidiobolomycosis forming centrofacial deformity in a 55-year-old farmer.

CASE REPORT

A 55-year-old farmer presented with a painless skin colored subcutaneous uniform swelling over the left side of nose encroaching to the left cheek for last 6 years. The swelling was 3cm × 5 cm in size [Figure 1]. The swelling was woody firm in consistency and non-tender. He had a history of nose bleeding two weeks back but no history of rhinitis or sinusitis. He had no history of diabetes, HIV infection, renal or any chronic disease, immunosuppressive drug intake, or trauma.

Figure 1

Facial swelling over the left side of nose extending to the left cheek

On rhinoscopic examination no mass or bleeding was noticed within the nasal cavities. All the routine blood reports were normal; fasting blood sugar was 101mg/dl, and blood for HIV -1 and HIV-2 was negative. X-ray chest posteroanterior view was normal. Computerized tomography scan of paranasal sinus revealed no abnormality in the sinus except a soft tissue swelling over the nose. Histopathological examination revealed multiple mixed inflammatory cells granulomas in the entire dermis consisting of neutrophils at the centre, surrounded by lymphohistiocytic infiltrate which is covered by respiratory epithelium. Splendore-Hoeppli phenomenon was present at the center of granuloma [Figure 2] at multiple sites as radiating eosinophilic material around the fungal hyphae. Grocott methinamine silver staining techniques confirmed the rigid, thick-walled fungal hyphae [Figure 3]. Culture showed no growth, hence species identification could not be done. Considering the clinical features and histopathological examination result we diagnosed it a case of conidiobolomycosis and prescribed oral therapy with potassium iodide solution and itraconazole 200 mg daily for 6 months. The swelling showed marked improvement in consistency and size, turned soft and smaller.

Figure 2

Histopathology showing Splendore-Hoeppli phenomenon at multiple sites in the dermis (H and E stain, x10)

Figure 3

Grocott methinamine silver stain showing the rigid, thick-walled fungal hyphae (x40)

DISCUSSION

Subcutaneous swelling over the nose may occur due to many reasons such as lymphoma, sarcoma, lymphatic edema, and subcutaneous zygomycoses such as mucormycosis or conidiobolomycosis. Conidiobolomycosis or a subcutaneous zygomycosis is a very rare condition. Human infection with Conidiobolus species most commonly occurs as a chronic rhinofacial mycosis in otherwise healthy hosts.[7] It is a localized zygomycotic infection caused by saprophytic fungus “C.coronatus” or “C.incongruous”.[12] As the fungus can survive in soils and dried vegetables for a long period of time, animals[89] are commonly affected. In northeastern Brazil, affected sheep and horses present as friable masses over the posterior part of the nasal cavity, often destroying the ethmoid turbinate bones[89] with dissemination of the lesion to lungs and brain in many.[10] The usual presentation of conidiobolomycosis in humans is an asymptomatic subcutaneous swelling over the nose. Another subset of subcutaneous zycomycosis, basidiobolomycosis, caused by B.ranarum, chiefly affects the trunk, limbs and limb girdle.[5] Disseminated basidiobolomycosis[10] and gastrointestinal basidiobolomycosis[11] has been reported among immunocompetent patients in tropical counties.

In the present case a painless, slowly progressive, skin colored, uniform subcutaneous swelling over the nose and left cheek in a healthy male was thought to be a tumor on first diagnosis, as it's incidence is much higher than rare disease such as conidiobolomycosis. All the investigations were normal. Histopathological examination and Grocott methinamine silver staining technique however revealed a suppurative granuloma and fungal hyphae. Based on the clinical features and histopathological examination result we diagnosed it as a case of conidiobolomycosis that has been rarely reported in the dermatology literature.[12]

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