Eczema or fungal infection: how to distinguish between the two?

The eczema is a chronic non-contagious skin disease. It causes inflammation that produces redness, scaling and itching. Eczema can affect all parts of the body and vary in severity, with periods of flare-ups and remission. The onset of eczema is very often linked to a combination of genetic factors, including a faulty skin barrier and an inadequate immune response, and environmental factors, such as exposure to allergens or irritants. This alteration of the skin barrier favours the penetration of foreign substances that trigger exaggerated and chronic inflammatory reactions.

Mycosis is a contagious skin condition caused by fungi, primarily yeasts of the genus Candida or dermatophytes. Yeast proliferation is favoured by a warm, humid environment, perspiration or prolonged corticosteroid use. Dermatophytes, on the other hand, feed on the keratin present in the skin, scalp and nails. It is this type of fungus that causes scalp mycosis, more commonly known as ringworm. Its symptoms are similar to those of the eczema of the scalp, with red circular lesions accompanied by itching. Likewise, fungal infections of the hands or feet may present with vesicles or scaling resembling those of the dyshidrotic eczema, making diagnosis challenging.

The symptoms of eczema and mycosis can be similar. In both cases, one observes red, scaly and pruritic patches which can affect the skin or scalp. However, certain clinical signs allow them to be distinguished. Knowing these factors helps to determine whether one is dealing with a mycosis or eczema.

• The localisation of plaques.

  Eczema often appears in specific areas, such as the folds of the elbows and knees, the face or the scalp, but it can then spread to other parts of the body depending on the progression of the disease. Mycosis, on the other hand, generally remains confined to a single area, most often the feet, the nails (onychomycosis) or the scalp (ringworm). It should be noted that the two conditions can overlap: a fungal infection can trigger an eczematous reaction by activating the immune system, while skin weakened by eczema becomes a favourable environment for fungal proliferation.

• The shape of the plates.

  The plaques associated with a fungal infection have a distinctive shape—round or oval with a sharply defined, sometimes raised border—producing the characteristic arc-shaped appearance of dermatophyte lesions. Certain fungal infections may also exhibit small vesicles or scales at the centre of the lesion. Eczema plaques, by contrast, have irregular, diffuse margins and can show extensive redness, crusting or fissures depending on the severity of the inflammation.

• The intensity of itching.

  Pruritus is a symptom of both eczema and fungal infection, but its severity varies. In the eczema, the itching is often intense and persistent, sometimes disturbing sleep at night. In the case of a fungal infection, pruritus is generally moderate and tolerable. Thus, intense itching may be a sign that you are suffering from eczema.

• The evolution over time.

  Eczema follows a chronic pattern, with flare-ups and periods of remission, whereas a fungal infection progresses more continuously if left untreated. The persistence of plaques, despite the use of emollient treatments and anti-inflammatory agents of the type corticosteroids, may point towards a fungal infection rather than eczema.

Eczema and mycosis: two diseases that must be differentiated because they are not treated in the same way.

Even though their symptoms can appear similar, eczema and fungal infection are underpinned by different biological mechanisms, which necessitates distinct therapeutic approaches. Eczema arises from a non-infectious skin inflammation, often associated with a compromised skin barrier and an overreactive immune response. Management therefore aims to restore the skin’s barrier function through daily application of emollients to limit dryness (xerosis) and to soothe inflammation during flare-ups using corticosteroids.

Mycosis, by contrast, is a fungal infection. In this case, corticosteroids are contraindicated: they can weaken local defences and promote the progression of the infection. Treatment therefore relies on antifungals, such as fluconazole or posaconazole, applied topically or sometimes prescribed orally depending on the extent of the mycosis.

Note : This article offers only a few pointers to distinguish between eczema and fungal infections. If you have any doubts, your first port of call should be to consult a dermatologist.

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