Fungal Skin Infections Practice Questions

Q: A 25-year-old man presents with multiple brownish patches on his trunk that appeared suddenly after exercising in hot weather. The lesions don't itch or scale. Wood's lamp examination shows yellow-green fluorescence. Which of the following is the most appropriate treatment?

Topical selenium sulfide. ***Topical selenium sulfide*** - This presentation is highly suggestive of **tinea versicolor** (pityriasis versicolor), caused by the yeast *Malassezia globosa*. - Topical selenium sulfide is a well-established and effective **antifungal agent** for treating tinea versicolor, often used as a shampoo or lotion. - It is the **first-line treatment** for localized disease. *Oral antibiotics* - **Tinea versicolor** is a fungal infection, not bacterial, rendering antibiotics ineffective. - Antibiotics are indicated for **bacterial infections** and would not address the underlying etiology here. *Topical steroids* - Topical steroids are **anti-inflammatory agents** and would not treat the fungal overgrowth causing tinea versicolor. - They could potentially worsen fungal infections by **suppressing local immunity**. *Oral antifungal* - While oral antifungals (such as fluconazole or itraconazole) can be used for widespread or recurrent tinea versicolor, **topical therapy** is generally preferred as first-line treatment for localized disease. - The initial presentation doesn't suggest the need for systemic treatment, making a **topical agent more appropriate** as the first choice due to fewer side effects and adequate efficacy.

Q: Microsporum involves:

Skin and hair. ***Skin and hair*** - *Microsporum* species are **dermatophytes** that commonly cause superficial fungal infections - They have a particular predilection for keratinized tissues like **skin and hair**, leading to conditions such as **tinea capitis** (scalp ringworm) and **tinea corporis** (body ringworm) - This is the characteristic pattern for *Microsporum* species including *M. canis*, *M. audouinii*, and *M. gypseum* *Skin and nails* - While *Microsporum* can affect the skin, its involvement with **nails (onychomycosis)** is extremely rare - Nail infections are typically associated with **Trichophyton rubrum** or **T. mentagrophytes**, not *Microsporum* *Hair and nails* - **Nail involvement** is not a characteristic of *Microsporum* infections - The main sites of infection are hair and smooth skin, not nails *Skin, hair and nails* - Including **nails** as a site for *Microsporum* is inaccurate; its primary targets are skin and hair only - While some dermatophytes (like *Trichophyton*) can affect all three tissues, *Microsporum* has specific tropism for skin and hair

Q: Selenium sulfide is indicated for treating?

Tinea versicolor. ***Tinea versicolor*** - **Selenium sulfide** is a well-established topical antifungal agent specifically effective in treating *Tinea versicolor*, an infection caused by *Malassezia* species. - Its mechanism involves interfering with the enzyme system of *Malassezia* and slowing down the growth of the fungus. *Tinea corporis* - While an antifungal is needed for *Tinea corporis*, selenium sulfide is generally **not the first-line treatment** and other azoles or allylamines are preferred. - *Tinea corporis* is caused by dermatophytes and skin inflammation as a ring-like lesion, which is distinct from the superficial infection of *Tinea versicolor*. *Candidiasis only* - **Candidiasis** is caused by *Candida* species and typically responds to azole antifungals like fluconazole or clotrimazole, not selenium sulfide. - Selenium sulfide has **limited efficacy** against *Candida* infections. *Mixed mycotic infections* - For **mixed mycotic infections**, treatment usually requires a broader-spectrum antifungal or a combination therapy, depending on the specific causative organisms. - Selenium sulfide is **too narrow-spectrum** to be a reliable treatment for undifferentiated mixed fungal infections.

Q: False about Tinea versicolor

Wood's lamp examination gives Apple green Fluorescence. ***Wood's lamp examination gives Apple green Fluorescence*** - **Tinea versicolor** typically exhibits a **yellow-green or yellowish-orange fluorescence** under Wood's lamp, not an apple-green fluorescence. - **Apple-green fluorescence** is characteristic of certain bacterial infections, such as those caused by *Pseudomonas aeruginosa*, but not for *Malassezia* species in Tinea versicolor. *Lesions can be both hypo & hyperpigmented* - This statement is true; **Tinea versicolor** lesions can indeed present as **hypopigmented (lighter)** or **hyperpigmented (darker)** patches. - The color variation is due to *Malassezia's* interference with melanin production or its direct pigment production. *It is superficial fungal infection caused by Malassezia* - This statement is true; **Tinea versicolor** is a **superficial fungal infection** of the skin caused by species of the yeast **Malassezia**. - The most common causative agent is **Malassezia globosa**, which is a normal commensal of the skin but can become pathogenic under certain conditions. *Scratch sign is positive* - This statement is true; the **scratch sign** (also known as the Besnier's sign) is positive in **Tinea versicolor**. - When the lesions are gently scraped, fine, **powdery scales** become more apparent, which is a characteristic finding.

Q: Pityriasis versicolor is caused by

Malassezia furfur. ***Malassezia furfur*** - **Pityriasis versicolor** is a superficial fungal infection caused by yeasts of the genus **Malassezia**, with **_Malassezia furfur_** being the most common species implicated. - This fungus normally resides on the skin but can overgrow under certain conditions (e.g., heat, humidity, oily skin), leading to characteristic **discolored patches**. *T. rubrum* - **_T. rubrum_** (Trichophyton rubrum) is a common **dermatophyte** responsible for various tinea infections, such as tinea pedis (**athlete's foot**) and tinea cruris (**jock itch**). - It causes infections in the **keratinized tissues** (skin, hair, nails) but is not the causative agent of pityriasis versicolor. *Candida species* - **_Candida_ species**, particularly **_Candida albicans_**, are yeasts that commonly cause **candidiasis** (e.g., oral thrush, vaginal yeast infections, diaper rash). - These infections typically present with **erythematous** and **pruritic** lesions, often in immunocompromised individuals or in moist body folds, which differs from pityriasis versicolor. *E. floccosum* - **_E. floccosum_** (Epidermophyton floccosum) is another **dermatophyte** primarily associated with infections of the skin and nails, causing conditions like **tinea pedis**, tinea cruris, and **onychomycosis**. - It does not cause pityriasis versicolor; this genus specifically attacks **superficial keratinized structures** and lacks the ability to invade living tissues.

Q: Hypersensitivity to dermatophyte antigens is called

ID reaction. ***ID reaction*** - An **ID reaction**, also known as a **dermatophytid reaction**, is a hypersensitivity response to **dermatophyte antigens** from a distant fungal infection. - It presents as sterile, secondary lesions (e.g., vesicles, papules) typically on hands, feet, or trunk, without direct fungal involvement. *Frenkel's reaction* - This term is not a widely recognized or established medical concept related to hypersensitivity or dermatophytes. - It does not describe a specific immunological reaction or dermatological condition. *Bachman reaction* - The **Bachman reaction** is not a standard medical term associated with hypersensitivity or dermatophyte infections. - There is no established clinical or immunological phenomenon known by this name in dermatology or immunology. *Schultz charlton reaction* - The **Schultz-Charlton reaction** is a blanching phenomenon seen in **scarlet fever**, where injecting scarlet fever antitoxin into a reddened area of skin causes it to blanch. - This reaction is specifically related to **Streptococcus pyogenes toxins** and has no connection to dermatophyte antigens.

Q: A 7-year-old boy presents with patchy hair loss, boggy scalp swelling and broken and fragmented hair follicles at the surface of the scalp resembling black dots. What is the next step in establishing a diagnosis:

KOH smear. ***KOH smear*** - A **KOH (potassium hydroxide) smear** is the **immediate next step** and first-line diagnostic test for suspected **tinea capitis** (ringworm of the scalp). - The clinical presentation (boggy swelling/kerion, black dots) strongly suggests an **endothrix fungal infection**, which requires rapid confirmation. - KOH mount is **rapid (results in minutes)**, inexpensive, minimally invasive, and highly effective for visualizing **fungal hyphae and spores**, allowing immediate initiation of antifungal therapy. - This test establishes the diagnosis at the point of care without delays. *Antibiotics* - **Antibiotics** treat bacterial infections, not fungal infections like tinea capitis. - While secondary bacterial superinfection can occur in kerion, the primary pathology here is **fungal** and requires antifungal treatment. - Unnecessary antibiotic use contributes to antimicrobial resistance and delays appropriate management. *Biopsy* - A **scalp biopsy** is invasive, costly, and typically reserved for unclear cases after initial non-invasive tests fail, or when evaluating scarring alopecia (cicatricial alopecia). - It is not the first-line diagnostic approach for clinically evident tinea capitis. - KOH smear should be attempted first before considering invasive procedures. *Culture* - **Fungal culture** is valuable for identifying the specific dermatophyte species (e.g., *Trichophyton tonsurans*, *Microsporum canis*) and guiding targeted therapy or epidemiological studies. - However, culture results take **2-4 weeks**, making it unsuitable as the immediate "next step" when rapid diagnosis is needed. - In practice, KOH smear is performed first; culture may be sent simultaneously but does not delay initial treatment decisions.

Q: An 8-year-old child has localized non-cicatricial alopecia over scalp with itching and scales. The diagnosis is :

Tinea Capitis. ***Tinea Capitis*** - **Tinea capitis** typically presents as **localized, non-cicatricial alopecia** with features like **scaling**, **itching**, and broken hairs, which are consistent with the child's symptoms. - It's a common **dermatophyte infection** of the scalp, particularly in children, caused by fungi like *Trichophyton* or *Microsporum*. *Lichen planus* - **Lichen planus** can cause alopecia, but it is typically a **cicatricial (scarring)** alopecia, unlike the non-cicatricial finding described. - It is more commonly associated with **purplish, polygonal, pruritic papules** on the skin and mucous membranes. *Tinea Barbae* - **Tinea barbae** specifically affects the **beard and mustache area** in adult males and would not present as alopecia on the scalp in an 8-year-old child. - It usually involves deep follicular inflammation with **pustules and nodules**. *Alopecia areata* - **Alopecia areata** is characterized by **smooth, circular patches of non-scarring hair loss** without associated scaling or significant itching. - The presence of **scaling and itching** in this case makes alopecia areata less likely.

Q: A 24 year old man had multiple, small hypopigmented macules on the upper chest and back for the last three months. The macules were circular, arranged around follicles and many had coalesced to form large sheets. The surface of the macules showed fine scaling. He had similar lesions one year ago which subsided with treatment. The most appropriate investigation to confirm the diagnosis is -

Potassium hydroxide preparation of scales. ***Potassium hydroxide preparation of scales*** - The description of **hypopigmented macules** with **fine scaling** on the upper chest and back, which coalesced and recurred, is highly suggestive of **Pityriasis versicolor** (also known as Tinea versicolor). - A **potassium hydroxide (KOH) preparation** of the scales directly visualizes the fungal elements (**hyphae and spores**, often described as "spaghetti and meatballs" appearance), confirming the diagnosis. *Slit skin smear from discrete macules* - A **slit skin smear** is primarily used for diagnosing mycobacterial infections, particularly **leprosy**, to detect acid-fast bacilli. - This procedure is not appropriate for diagnosing superficial fungal infections like Pityriasis versicolor. *Skin biopsy of coalesced macules* - While a **skin biopsy** can show fungal elements in the stratum corneum, it is an invasive and generally unnecessary procedure for diagnosing Pityriasis versicolor. - **KOH preparation** is a faster, simpler, and less invasive method that provides a definitive diagnosis. *Tzanck test* - The **Tzanck test** is used to identify multinucleated giant cells characteristic of viral infections, such as **herpes simplex virus** or **varicella-zoster virus**. - It involves scraping the base of a vesicle or bulla, which is not consistent with the described presentation of scaling macules.

Q: A 10-year-old boy presented with painful boggy swelling of scalp, multiple sinuses with purulent discharge, easily pluckable hair, and lymph nodes enlarged in occipital region, which of the following would be most helpful for diagnostic evaluation?

KOH mount. ***KOH mount*** - The symptoms of **painful boggy scalp swelling**, **purulent discharge**, **easily pluckable hair**, and **occipital lymphadenopathy** in a child are highly suggestive of **Tinea capitis**, specifically **Kerion**. - A **KOH mount** is the most direct and rapid method to identify fungal elements (hyphae and spores) in hair shafts and scales, confirming the diagnosis of a dermatophyte infection. *Bacterial culture* - While there is **purulent discharge**, the primary presentation with **boggy swelling** and **hair loss** is more indicative of a fungal etiology. - A bacterial culture would only be useful to rule out secondary bacterial infection, but not as the initial diagnostic step for the described primary fungal condition. *Biopsy and Giemsa staining* - A **biopsy** is an invasive procedure and generally not the first-line diagnostic test for uncomplicated **Tinea capitis/Kerion**, where a non-invasive KOH mount is sufficient. - **Giemsa staining** is primarily used for identifying certain bacteria, parasites, or cellular morphology, but it is not the standard or most efficient method for diagnosing fungal infections of the hair. *Patch test, Gram staining and Tzank smear* - A **patch test** is used to diagnose **allergic contact dermatitis** and is irrelevant to the presented symptoms. - **Gram staining** is for bacterial identification, and a **Tzank smear** is used for viral infections like herpes, neither of which are indicated by the clinical picture of a fungal scalp infection.

Question 1

A 25-year-old man presents with multiple brownish patches on his trunk that appeared suddenly after exercising in hot weather. The lesions don't itch or scale. Wood's lamp examination shows yellow-green fluorescence. Which of the following is the most appropriate treatment?

Accepted Answer

Topical selenium sulfide

Answer

Oral antibiotics

Answer

Topical steroids

Answer

Oral antifungal

Question 2

Microsporum involves:

Accepted Answer

Skin and hair

Answer

Skin and nails

Answer

Hair and nails

Answer

Skin, hair and nails

Question 3

Selenium sulfide is indicated for treating?

Accepted Answer

Tinea versicolor

Answer

Tinea corporis

Answer

Candidiasis only

Answer

Mixed mycotic infections

Question 4

False about Tinea versicolor

Accepted Answer

Wood's lamp examination gives Apple green Fluorescence

Answer

Lesions can be both hypo & hyperpigmented

Answer

It is superficial fungal infection caused by Malassezia

Answer

Scratch sign is positive

Question 5

Pityriasis versicolor is caused by

Accepted Answer

Malassezia furfur

Answer

T. rubrum

Answer

Candida species

Answer

E. floccosum

Question 6

Hypersensitivity to dermatophyte antigens is called

Accepted Answer

ID reaction

Answer

Frenkel's reaction

Answer

Bachman reaction

Answer

Schultz-Charlton reaction

Question 7

A 7-year-old boy presents with patchy hair loss, boggy scalp swelling and broken and fragmented hair follicles at the surface of the scalp resembling black dots. What is the next step in establishing a diagnosis:

Accepted Answer

KOH smear

Answer

Antibiotics

Answer

Biopsy

Answer

Culture

Question 8

An 8-year-old child has localized non-cicatricial alopecia over scalp with itching and scales. The diagnosis is :

Accepted Answer

Tinea Capitis

Answer

Lichen planus

Answer

Tinea Barbae

Answer

Alopecia areata

Question 9

A 24 year old man had multiple, small hypopigmented macules on the upper chest and back for the last three months. The macules were circular, arranged around follicles and many had coalesced to form large sheets. The surface of the macules showed fine scaling. He had similar lesions one year ago which subsided with treatment. The most appropriate investigation to confirm the diagnosis is -

Accepted Answer

Potassium hydroxide preparation of scales

Answer

Slit skin smear from discrete macules

Answer

Skin biopsy of coalesced macules

Answer

Tzanck test

Question 10

A 10-year-old boy presented with painful boggy swelling of scalp, multiple sinuses with purulent discharge, easily pluckable hair, and lymph nodes enlarged in occipital region, which of the following would be most helpful for diagnostic evaluation?

Accepted Answer

KOH mount

Answer

Bacterial culture

Answer

Biopsy and giemsa staining

Answer

Patch test, gram staining and Tzank smear

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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