Entomophthoromycosis: causes, symptoms, diagnosis, and treatment

Entomophthoromycosis is a mycosis caused by Entomophthorales, and mainly manifested by chronic inflammation or granuloma of subcutaneous tissue and submucosa.

According to different pathogens, entomophthoromycosis can be divided into entomophthoromycosis conidiobolae and basidiobolomycosis.


Entomophthoromycosis conidiobolae

Causes

The pathogen is Conidiobolus coronata, a saprophytic fungus in soil that can be isolated from decaying plants, and is also a pathogen of some arthropods, insects, and horses.

Most patients are 20 - 40 years old agricultural workers.

Signs and Symptoms

The main symptoms are nasal masses. Skin lesions occur initially in the turbinate mucosa, gradually spreading peripherally to the submucosa, nasal septum, nostrils, and nasal sinuses, bilaterally or unilaterally. The most common symptoms are nasal obstruction or nasal discharge. Masses and edema of the cheeks, forehead, lips, and eyelids result in strange facial appearance. The masses are uneven and can block the nostrils. The masses adhere to the deep tissue, without pain, cannot be pushed, with or without erythema, and generally do not rupture. The skin over the masses is movable. There is no fever, and good general condition is present.

Histopathology

Eosinophilic granulomas in the subcutaneous tissue containing short, thick, 6 - 25μm in diameter, 8 - 12μm wide, thin-walled, branched or septate hyphae can be seen. There are 3 - 5μm wide eosinophilic substances on the periphery of the hyphae, which is known as Splendore-Hoeppli phenomenon.

Diagnosis

On the basis of clinical findings and hyphae found in microscopy or histopathology, the disease can be diagnosed.

Treatment

Systemic potassium iodide or sulfamethoxazole can be administered until one month after the skin lesions subside completely.


Basidiobolomycosis

Basidiobolomycosis is a skin infection caused by Basidiobolus haptosporus, sometimes affecting other tissues and organs.

Causes

The pathogen is Basidiobolus haptosporus, which is present in the soil, decaying plants, and intestines of amphibians and reptiles such as frogs, toads, geckos, and lizards. Insects can be carriers.

Signs and Symptoms

The disease occurs predominantly in the extremities and buttocks, especially the lower extremities, as well as the neck, chest, and back.

The primary lesions are subcutaneous nodules, expanding in size and amount, developing into sharply demarcated, raised, hemispherical plaques. There is no redness, rupture, edema, undulation, and tenderness. After oral glucocorticoids, suppuration, rupture, and pyorrhea occur, which is helpful for fungal examination. The plaques are as firm as rubber and can adhere to the skin, the skin may be dark, but the plaques do not adhere to the tendon. The disease is generally chronic, and can persist for months to years. Plaques generally account for 2/3 of the thigh or upper arm or 1/2 of the buttocks.

If the lesions are limited to the skin, patients are generally asymptomatic or with only local discomfort, without pain, without fever. If visceral infections are present, there may be various degrees of systemic or local discomfort, generally mild.

Histopathology

A large number of eosinophils, as well as neutrophils, can be seen in the early stage of acute inflammation or on the edges of plaques. Thick, short, 8 - 12μm in diameter, branched or unbranched, septate or non-septate hyphae can be seen in the microabscesses. The hyphae are surrounded by a 3 - 5μm wide eosinophilic substances, which is known as Splendore-Hoeppli phenomenon. In the middle stage, tuberculoid structures composed of epithelioid cells and foreign body giant cells in the central plaques may be seen, and there may be hyphae. In the late stage or when the lesions are healing, the tuberculoid structures are absent, and fibroplasia is present. In addition to eosinophils, there are fibroblasts, lymphocytes, and plasma cells, but no hyphae. Neither obvious changes in blood vessels nor mycelium invasion into the blood vessel wall can be seen.

Diagnosis

The diagnosis is mainly based on the clinical manifestations and hyphae found in microscopy or histopathology.

Treatment

Systemic potassium iodide or imidazoles can be administered until the skin lesions subside completely.