Conidiobolomycosis

Conidiobolomycosis
Other names	Rhinoentomophthoromycosis[1]
Conidiobolus coronatus[2]
Specialty	Infectious disease[3]
Symptoms	Firm painless swelling in nose, sinuses, cheeks and upper lips, blocked nose, runny nose, nose bleed[4]
Complications	Facial disfigurement, partial or full blindness.[4] Severe disseminated disease if weak immune system[5]
Usual onset	Slowly progressive[6]
Duration	Long term[4]
Causes	fungi of the genus Conidiobolus[4]
Diagnostic method	Medical imaging, biopsy, microscopy, culture[5]
Differential diagnosis	Soft tissue tumors,[4] Mucormycosis
Treatment	Antifungals, surgical debridement[6]
Medication	oral Itraconazole, topical Potassium iodide[6] Severe disease: intravenous Amphotericin B[5]
Prognosis	Longterm morbidity: facial disfigurement,[4] good response to treatment[7]
Frequency	Rare, M>F[4] adults>children[5]
Deaths	Rare[6]

Conidiobolomycosis is a rare long-term fungal infection that is typically found just under the skin of the nose, sinuses, cheeks and upper lips.^[3][4] It may present with a nose bleed or a blocked or runny nose.^[4] Typically there is a firm painless swelling which can slowly extend to the nasal bridge and eyes, sometimes causing facial disfigurement.^[6]

Most cases are caused by Conidiobolus coronatus, a fungus found in soil and in the environment in general, which can infect healthy people.^[4] It is usually acquired by inhaling the spores of the fungus, but can be by direct infection through a cut in the skin such as an insect bite.^[3][4]

The extent of disease may be seen using medical imaging such as CT scanning of the nose and sinus.^[4] Diagnosis may be confirmed by biopsy, microscopy, culture and histopathology.^[4][5] Treatment is with long courses of antifungals and sometimes cutting out infected tissue.^[6] The condition has a good response to antifungal treatment,^[7] but can recur.^[8] The infection is rarely fatal.^[6]

The condition occurs more frequently in adults working or living in the tropical forests of South and Central America, West Africa and Southeast Asia.^[4][5] Males are affected more than females.^[4] The first case in a human was described in Jamaica in 1965.^[4]

Signs and symptoms

The infection presents with firm lumps just under the skin of the nose, sinuses, upper lips, mouth and cheeks.^[4] The swelling is painless and may feel "woody".^[8] Sinus pain may occur.^[6] Infection may extend to involve the nasal bridge, face and eyes, sometimes resulting in facial disfigurement.^[4] The nose may feel blocked or have a discharge, and may bleed.^[4]

Cause

Conidiobolomycosis is a type of Entomophthoromycosis, the other being basidiobolomycosis, and is caused by mainly Conidiobolus coronatus, but also Conidiobolus incongruus and Conidiobolus lamprauges^[4]

Mechanism

Conidiobolomycosis chiefly affects the central face, usually beginning in the nose before extending onto paranasal sinuses, cheeks, upper lip and pharynx.^[5] The disease is acquired usually by breathing in the spores of the fungus, which then infect the tissue of the nose and paranasal sinuses, from where it slowly spreads.^[4] It can attach to underlying tissues, but not bone.^[4][5] It can be acquired by direct infection through a small cut in the skin such as an insect bite.^[3] Thrombosis, infarction of tissue and spread into blood vessels does not occur.^[4] Deep and systemic infection is possible in people with a weakened immune system.^[4] Infection causes a local chronic granulomatous reaction.^[6]

Diagnosis

The condition is typically diagnosed after noticing facial changes.^[6] The extent of disease may be seen using medical imaging such as CT scanning of the nose and sinus.^[4] Diagnosis can be confirmed by biopsy, microscopy, and culture.^[4] Histology reveals wide but thin-walled fungal filaments with branching at right-angles.^[5] There are only a few septae.^[5] The fungus is fragile and hence rarely isolated.^[1] An immunoallergic reaction might be observed, where a local antigen–antibody reaction causes eosinophils and hyaline material to surround the organism.^[5] Molecular methods may also be used to identify the fungus.^[5]

Differential diagnosis

Differential diagnosis includes soft tissue tumors.^[4] Other conditions that may appear similar include mucormycosis, cellulitis, rhinoscleroma and lymphoma.^[6]

Treatment

Treatment is with long courses of antifungals and sometimes cutting out infected tissue.^[6] Generally, treatment is with triazoles, preferably itraconazole.^[5] A second choice is potassium iodide, either alone or combined with itraconazole.^[5] In severe widespread disease, amphotericin B may be an option.^[5] The condition has a good response to antifungal treatment,^[7] but can recur.^[8] The infection is rarely fatal but often disfiguring.^[6]

Epidemiology

The disease is rare, occurring mainly in those working or living in the tropical forests of West Africa, Southeast Asia, South and Central America,^[4] as well India, Saudi Arabia and Oman.^[5] Conidiobolus species have been found in areas of high humidity such as the coasts of the United Kingdom, eastern United States and West Africa.^[6]

Adults are affected more than children.^[5] Males are affected more than females.^[4]

History

The condition was first reported in 1961 in horses in Texas.^[4] The first case in a human was described in 1965 in Jamaica.^[4] Previously this genus was thought to only infect insects.^[4]

Other animals

Conidiobolomycosis affects spiders, termites and other arthropods.^[4] The condition has been described in dogs, horses, sheep and other mammals.^[9] Affected mammals typically present with irregular lumps in one or both nostrils that cause obstruction, bloody nasal discharge and noisy abnormal breathing.^[9]

References

1. Arora P, Sardana K, Madan A, Khurana N (2016). "An Old Woman with a Lump". Indian Journal of Dermatology. 61 (6): 697–699. doi:10.4103/0019-5154.193705. PMC 5122299. PMID 27904202.
2. Nie Y, Yu DS, Wang CF, Liu XY, Huang B (24 August 2021). "A taxonomic revision of the genus Conidiobolus (Ancylistaceae, Entomophthorales): four clades including three new genera". MycoKeys (66): 55–81. doi:10.3897/mycokeys.66.46575. PMC 7136305. PMID 32273794.
3. "ICD-11 - ICD-11 for Mortality and Morbidity Statistics". icd.who.int. Retrieved 5 June 2021.
4. Chander J (2018). Textbook of Medical Mycology (4th ed.). New Delhi: Jaypee Brothers Medical Publishers Ltd. pp. 599–603. ISBN 978-93-86261-83-0.
5. Queiroz-Telles F, Fahal AH, Falci DR, Caceres DH, Chiller T, Pasqualotto AC (November 2017). "Neglected endemic mycoses". The Lancet. Infectious Diseases. 17 (11): e367–e377. doi:10.1016/S1473-3099(17)30306-7. PMID 28774696.
6. Sherchan R, Zahra F (2021). "Entomophthoromycosis". StatPearls. StatPearls Publishing. PMID 34033391.
7. Gupta N, Sonej M (March 2019). "JCDR – Conidiobolus coronatus, Conidiobolus incongruus, Entomophthoramycosis". Journal of Clinical and Diagnostic Research. 13 (3). doi:10.7860/JCDR/2019/40142.12701.
8. Das SK, Das C, Maity AB, Maiti PK, Hazra TK, Bandyopadhyay SN (November 2019). "Conidiobolomycosis: An Unusual Fungal Disease-Our Experience". Indian Journal of Otolaryngology and Head and Neck Surgery. 71 (Suppl 3): 1821–1826. doi:10.1007/s12070-017-1182-6. PMC 6848416. PMID 31763253.
9. Sellon DC, Long MT (2007). Equine Infectious Diseases. St. Louis, Missouri: Saunders Elsevier. p. 417. ISBN 978-1-4160-2406-4.

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