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Fungal Infections of the Nails

Onychomycosis (tinea unguium) is a fungal infection of the fingernails or toenails. It is usually caused by dermatophytes or Candida.


Most patients with onychomycosis are asymptomatic and won’t notice anything physical until the cosmetic affects take place (deformities of the nail, discolouration, etc.) [6]. As the fungal infection continues, it can cause chronic pain and which can be exacerbated by nail cutting, footwear, or pressure. When the infection is not treated it can cause pain or discomfort at all times, lead to a loss of dexterity, can cause low self-esteem and a lack of social interaction due to the patient’s reduced self-consciousness caused by the cosmetic nature of the infection.

Nail Abnormality
  • It is very common, and it accounts for around 50% of all nail abnormalities. Nail abnormalities affect about 7% of the adult population.[healdove.com]
  • There are times when it becomes difficult to tell onychomycosis apart from other conditions that cause nail abnormalities such as psoriasis and trauma.[probitymedical.com]
  • […] caused by dermatophytes, yeast and non-dermatophyte molds that lead to distortion, discoloration, thickening and detachment from the nail bed Onychomycosis accounts for up to 30% of all superficial infections of skin and constitutes about a half of all nail[clinicaltrials.gov]
  • However, this diagnosis cannot be excluded in children presenting with suggestive nail abnormalities, and mycology should be performed.[tandfonline.com]
  • Abnormal Appearance of Nail- Patient often complaints of discoloration and thickening of nail. Abnormal Odor- Few patients may complaint of abnormal odor. Onychomycosis Signs Include- Examination of Nail- Increased thickness of the nail(s).[epainassist.com]
  • Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver. Today, a mycologist is required to interpret fungal culture testing.[ncbi.nlm.nih.gov]
  • 18, 19 The cost for in-office KOH testing was based on the clinical laboratory fee schedule for Current Procedural Terminology code 87220, and the cost for PAS testing was based on a combination of professional costs for trimming the nails (G0127), pathologist[archderm.jamanetwork.com]
  • The KOH wet mount preparation of subungual debris is not a very sensitive method and clinicians seldom perform it on nail specimens.13 Currently, the most sensitive test is a pathologist read biopsy of nail clippings stained with periodic acid Schiff[podiatrytoday.com]
Weight Loss
  • Abstract We present a case of a 73-year-old woman who presented with chronic watery diarrhea, weight loss, and frequent sinus and nail fungal infections.[ncbi.nlm.nih.gov]
Chronic Watery Diarrhea
  • Abstract We present a case of a 73-year-old woman who presented with chronic watery diarrhea, weight loss, and frequent sinus and nail fungal infections.[ncbi.nlm.nih.gov]
Nail Deformity
  • deformity, but only if the patient has tinea pedis.[merckmanuals.com]
  • For those who want a faster option, the patient should be referred to a dermatologist or a surgeon for complete nail removal. [14] [15] (Level V) Outcomes For patients who delay in seeking care, the nail deformity usually progresses and may lead to disfigurement[ncbi.nlm.nih.gov]
  • Differential diagnosis [ edit ] In many cases of suspected nail fungus there is actually no fungal infection, but only nail deformity. [16] [17] To avoid misdiagnosis as nail psoriasis, lichen planus, contact dermatitis, nail bed tumors such as melanoma[en.wikipedia.org]
  • Toenail onychomycosis can cause nail deformity, embarrassment, pain and walking difficulties. Some populations, such as individuals with diabetes, are at higher risk for developing secondary complications such as infections.[raysahelian.com]
  • There was no family history of psoriasis, Darier's disease, pachyonychia congenita, or lichen planus. The infant was born to parents with no known risk factors for human immunodeficiency virus infection, thus testing of the infant was not addressed.[jamanetwork.com]
  • Pachyonychia congenita. Nail lesions in a 7-year-old boy. All nails show mild thickening with distal onycholysis and subungual hyperkeratosis. Published online: 10 January 2014 Figure 8.[tandfonline.com]
  • The differential diagnosis includes inflammatory disorders such as psoriasis and lichen planus; genetic disorders such as pachyonychia congenita; as well as nail unit neoplasms, repeated trauma, drugs, bacterial infections, and systemic diseases.[dermatologyadvisor.com]
  • Differential diagnosis include idiopathic onycholysis, bacterial infections, traumatic onychodystrophies, lichen planus, psoriasis, contact dermatitis, pachyonychia congenita and nail bed tumors.[scielo.br]
  • 64e6c1a1710838655cc965f0e1ea13052e867597ac43370498029d1bc5831201} KOH The nail should be sent to a reputable laboratory for culture processing Differential Diagnosis of Onychomycosis Psoriasis Lichen planus Contact dermatitis Traumatic onychodystrophies Congenital pachyonychia[drfungus.org]
  • Photodynamic therapy (PDT) is one of those being currently studied, which involves the use of photosensitizer and a light source to excite the photosensitizer to generate reactive oxygen species.[ncbi.nlm.nih.gov]
  • One promising alternative is photodynamic antimicrobial chemotherapy, or PACT: an irradiated photosensitizer creates singlet oxygen molecules which destroy pathogens without damaging human cells.[ncbi.nlm.nih.gov]
  • An hour after the photosensitization, the nail was illuminated using a light source based on light emitting diodes (LEDs) in the red wavelength (630 nm, at a total dose of 54 J/cm(2)).[ncbi.nlm.nih.gov]
  • Photosensitizers for photodynamic therapy (PDT) and a new laser system are emerging therapeutic options [ 38, 39 ].[ncbi.nlm.nih.gov]
  • Evaluation of photosensitizer penetration into sound and decayed dentin: a photoacoustic spectroscopy study. Photodiagnosis Photodyn. Ther. 21, 108–114. doi: 10.1016/j.pdpdt.2017.11.008 PubMed Abstract CrossRef Full Text Google Scholar Oliveira, A.[frontiersin.org]
Scaly Rash
  • We present a case of a 32-year-old white man who presented with a red scaly rash and nail dystrophy after adopting a pet rat 10 years prior to presentation.[ncbi.nlm.nih.gov]
Koebner Phenomenon
  • Moreover, onychomycosis could exacerbate psoriasis through Koebner phenomenon and the treatment of psoriasis could predispose to onychomycosis.[ncbi.nlm.nih.gov]
  • For analysis of the complete cure rate, subjects prematurely withdrawn from the study were regarded as not having been cured.[ncbi.nlm.nih.gov]
  • When the results show no fungi are present (negative test result) participants are then withdrawn from the study.[dx.doi.org]


Onychomycosis might be clinically diagnosed on a preliminary level but in order to get a confirmed diagnosis, laboratory tests are necessary. These tests can include cultures, histology, and a potassium hydroxide (KOH) examination [7] [8]. A microscopic exam will also be done alongside scrapings and clippings of the nails. There might be several samples needed in order to confirm cases when OM is caused by nondermatophytic moulds.

Differentail diagnosis of onychomycosis may be misdiagnosed as nail psoriasis, lichen planus, contact dermatitis, yellow nail syndrome, iron deficiency, chronic paronychia or simple trauma.

Alanine Aminotransferase Increased
  • aminotransferase increased 9 (8.9) 0 (0.0) Aspartate aminotransferase increased 8 (7.9) 0 (0.0) Blood creatinine increased 1 (1.0) 0 (0.0) γ‐Glutamyltransferase increased 16 (15.8) 1 (1.9) Hemoglobin decreased 1 (1.0) 0 (0.0) Red blood cell count decreased[ncbi.nlm.nih.gov]
Alkaline Phosphatase Increased
  • phosphatase increased 2 (2.0) 1 (1.9) Discussion Itraconazole and terbinafine hydrochloride are the only oral agents marketed in Japan thus far for the treatment of onychomycosis, and more than 20 years have passed since the marketing approvals for these[ncbi.nlm.nih.gov]
Creatinine Increased
  • increased 1 (1.0) 0 (0.0) γ‐Glutamyltransferase increased 16 (15.8) 1 (1.9) Hemoglobin decreased 1 (1.0) 0 (0.0) Red blood cell count decreased 1 (1.0) 0 (0.0) White blood cell count decreased 1 (1.0) 0 (0.0) White blood cell count increased 1 (1.0)[ncbi.nlm.nih.gov]
Hemoglobin Decreased
  • decreased 1 (1.0) 0 (0.0) Red blood cell count decreased 1 (1.0) 0 (0.0) White blood cell count decreased 1 (1.0) 0 (0.0) White blood cell count increased 1 (1.0) 0 (0.0) Blood alkaline phosphatase increased 2 (2.0) 1 (1.9) Discussion Itraconazole and[ncbi.nlm.nih.gov]
Liver Function Tests Abnormal
  • The incidence of increased γ‐GT was higher than those of other liver function test abnormalities.[ncbi.nlm.nih.gov]
Aspergillus Clavatus
  • We present a case of onychomycosis due to Aspergillus clavatus for the first time worldwide. The patient was an immunocompetent 32-year-old woman who identified with Psoriasis of the nail.[ncbi.nlm.nih.gov]
  • Mehraban Falahati, Aynaz Ghojoghi, Mahdi Abastabar, Zeinab Ghasemi, Shirin Farahyar, Maryam Roudbary, Mohammad Taghi Hedayati, Mojtaba Taghizadeh Armaki and Akbar Hoseinnejad, The First Case of Total Dystrophic Onychomycosis Caused by Aspergillus clavatus[doi.org]


The type of treatment necessary is dependent on the type of onychomycosis, severity of the condition, and how many nails are affected by the infection [9]. Proximal subungual onychomycosis and distal lateral subungual onychomycosis involving the lunula region require systemic treatment while white superficial onychomycosis and distal lateral subungual onychomycosis limited to the distal nail can usually be successfully treated topically. Some cases may need a combination of topical and systemic treatments. 

Oral medications include terbinafine, itraconazole, griseofulvin and fluconazole. Topical agents available for the treatment of onychomycosis include ciclopirox nail paint, amorolfine, tavaborole or efinaconazole. Depending on the type of onychomycosis and severity of the condition, other medications and treatment options such as laser or light therapy and surgery may be beneficial.


Since onychomycosis is a fungal infection, recurrence can occur even after successful treatment and recovery. This has been seen in 10 to 50 percent of reported cases [5]. The infection can cause pain and discomfort in patients and can also leave the nail permanently damaged or disfigured. Associated infections can occur due to OM if the patient is immunocompromised from a preexisting condition like diabetes. Diabetic patients, people suffering from leukemia, and patients who have undergone an organ transplant are thought to be high risk for this infection.


There are various pathogens that are associated with the onset of OM. Dermatophytes, yeasts, or nondermatophyte molds are associated with OM [2]. The dermatophytes Trichophyton rubrum and Trichophyton mentagrophytes account for the majority of cases.

Certain pathogens seem to be more prevalent in different regions. For example, dermatophytes seem to be more responsible for OM in western countries that have temperate conditions and candida and nondermatophytic moulds are more associated with OM in patients that live in the subtropics or tropics where the climate is humid and warm.


Internationally, onychomycosis affects around three to eight percent of people in developed countries including Spain, Finland, and the United Kingdom. In North America, OM affects between two and 13 percent of the population [3].

This fungal infection is responsible for around 50 percent of all reported nail disorders and it is considered to be the most common nail disease in the adult population. 

Sex distribution
Age distribution


As previously stated, different pathogens can lead to the development of onychomycosis depending on the region. The subtype of the fungal infection can also change the pathophysiology of it.

Distal lateral subungual onychomycosis is considered to be the most common form of OM and is usually distinguishable by the inflammation associated with it. DLSO spreads from the plantar skin to the nail bed through the hyponychium [4]. In endonyx onychomycosis, a form of distal lateral subungual onychomycosis, the pathogen infects the nail through the skin surrounding the nail before directly entering the nail plate.

White superficial onychomycosis is less common and the nail plate is the primary site of invasion. In the case of proximal subungual onychomycosis an invasion of pathogens via the proximal nail fold through the cuticle area.

Finally, the most severe cases of OM, total dystrophic OM, involves the entire nail unit including the plate, the bed, and the matrix.


Preventing onychomycosis has to do with hygiene and general upkeep for the finger and toenails. The following steps may be advised [10]:

  • Avoid walking barefoot
  • Avoid wearing old shoes that offer little protection
  • Avoid unsanitary nail salons that can lead to fungal infections
  • Avoid using artificial nails and glues
  • Keep nails short and dry
  • Use antifungal agents 
  • Wash and dry hands and feet properly
  • Wash hands after coming into contact with infected nails to avoid spreading
  • Wear absorbent socks to keep feet dry
  • Wear rubber gloves when exposed to excessive water (washing dishes, for example)
  • Wear shoes that can vent air and reduce humidity


Onychomycosis, abbreviated OM, is a fungal infection that affects the fingernails and toenails [1]. It is divided into five subtypes including candidal onychomycosis, distal lateral subungual onychomycosis (DLSO), endonyx onychomycosis (EO), proximal subungual onychomycosis (PSO), and white superficial onychomycosis (WSO). There is a chance that more than one subtype of OM can be present at one given time. The more advanced form of general OM which encompasses all of the subtypes is known as total dystrophic onychomycosis. The fungal infection involves the all parts of the nail structure including the nail plate, the nail bed, and the nail matrix.

This condition is not fatal at all but it can be painful and lead to permanent disfigurement. It is also a cosmetic concern to people. The pain and possible disfigurement can lead to physical and occupational limitations and psychosocial and emotional issues due to the cosmetic aspect of the disorder. These emotional problems can have an overall impact on a person’s quality of life.

Patient Information

Onychomycosis (OM), is a fungal infection that attacks the finger and toenails. It is quite common especially in humid climates. The infection is characterized by a white or yellow discoloration that appears under the nail. As the infection progresses and grows, the spot gets bigger and becomes more noticeable. The nail will become unhealthy and begin to crumble around the edges at this point. In most cases, only one nail is affected but it is possible for the infection to spread if left untreated.

OM is usually considered to be a mild infection and it is easily treated with either topical or systemic medications or it can remedy itself. It can cause pain and discomfort but it it’s mild it might not affect the person physically at all. There are more severe cases that can cause a good amount of physical pain and lead to permanent deformities and a loss of dexterity. 

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Last updated: 2019-07-11 22:08