Tinea incognito is a fungal infection (mycosis

Mycosis

A mycosis is a fungal infection of animals, including humans. Mycoses are common, and a variety of environmental and physiological conditions can contribute to the development of fungal diseases...

) of the skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 caused by the presence of a topical

Topical

In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...

 immunosuppressive agent

Immunosuppressive drug

Immunosuppressive drugs or immunosuppressive agents are drugs that inhibit or prevent activity of the immune system. They are used in immunosuppressive therapy to:...

. The usual agent is a topical corticosteroid

Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...

 (topical steroid). As the skin fungal infection has lost some of the characteristic features due to suppression of inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

, it may have a poorly defined border, skin atrophy, telangiectasia

Telangiectasia

Telangiectasias /tɛ.læn.dʒiː'ɛk.teɪ.ʃi:ə/ are small dilated blood vessels near the surface of the skin or mucous membranes, measuring between 0.5 and 1 millimeter in diameter. They can develop anywhere on the body but are commonly seen on the face around the nose, cheeks, and chin...

, and florid

Florid

Florid is a word with several usages including:* Having a rosy complexion, ruddy* Excessively intricate, elaborately ornate or complicated, highly oramented...

 growth. Occasionally, secondary infection with bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 occurs with concurrent pustules and impetigo

Impetigo

Impetigo is a highly contagious bacterial skin infection most common among pre-school children. People who play close contact sports such as rugby, American football and wrestling are also susceptible, regardless of age. Impetigo is not as common in adults. The name derives from the Latin impetere...

.

Diagnosis

Clinical suspicion arises especially if the eruption is on the feet, ankle

Ankle

The ankle joint is formed where the foot and the leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot...

, legs

Human leg

The human leg is the entire lower extremity or limb of the human body, including the foot, thigh and even the hip or gluteal region; however, the precise definition in human anatomy refers only to the section of the lower limb extending from the knee to the ankle.Legs are used for standing,...

, or groin

Groin

In human anatomy, the groin areas are the two creases at the junction of the torso with the legs, on either side of the pubic area. This is also known as the medial compartment of the thigh. A pulled groin muscle usually refers to a painful injury sustained by straining the hip adductor muscles...

. A history of topical steroid or immunosuppressive agent is noted.

Confirmation is with a skin scraping and microscopic

Microscopic

The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.-History:...

 exam with potassium hydroxide

Potassium hydroxide

Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...

 solution

Solution

In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

. Characteristic hyphae are seen running through the squamous epithelial cells

Squamous epithelium

In anatomy, squamous epithelium is an epithelium characterised by its most superficial layer consisting of flat, scale-like cells called squamous epithelial cells...

. Fungal culture

Cell culture

Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...

 is not necessary, but might be considered if the patient is using a combination antifungal and topical steroid product.

Cause

The use of a topical steroid is the most common cause. Frequently, a combination topical steroid and antifungal cream is prescribed by a physician. These combinations include betamethasone dipropionate

Betamethasone

Betamethasone is a potent glucocorticoid steroid with anti-inflammatory and immunosuppressive properties. Unlike other drugs with these effects, betamethasone does not cause water retention. It is applied as a topical cream, ointment, foam, lotion or gel to treat itching...

 and clotrimazole

Clotrimazole

Clotrimazole is an antifungal medication commonly used in the treatment of fungal infections such as vaginal yeast infections, oral thrush, and ringworm...

 (trade name

Trade name

A trade name, also known as a trading name or a business name, is the name which a business trades under for commercial purposes, although its registered, legal name, used for contracts and other formal situations, may be another....

 Lotrisone) and triamcinolone acetonide

Triamcinolone acetonide

Triamcinolone acetonide is a synthetic corticosteroid used to treat various skin conditions and to relieve the discomfort of mouth sores. It is a more potent type of triamcinolone, being about 8 times as effective as prednisone.-Medical use:...

 and clotrimazole

Clotrimazole

Clotrimazole is an antifungal medication commonly used in the treatment of fungal infections such as vaginal yeast infections, oral thrush, and ringworm...

. In area of open skin, these combinations are acceptable in treating fungal infection of the skin. Unfortunately, in area where the skin is occluded (groin, buttock crease, armpit), the immunosuppression by the topical steroid might be significant enough to cause tinea incognito to occur--even in the presence of an effective antifungal.

Treatment

The removal of the offending topical steroid or immunosuppressive agent. Treatment with a topical antifungal is adequate. If the tinea incognito is extensive, treatment with a systemic antifungal for one to two weeks may be needed.

If the tinea incognito is very inflammatory and itch

Itch

Itch is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience. Modern science has shown that itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response...

y, a milder topical steroid might be used for a limited amount of time (three to seven days), together with the antifungal.