Fungal Skin Infections Practice Questions

Q: A child presents with multiple patchy areas of hair loss, scales, and itching. The sister also had similar lesions. What is the most likely diagnosis?

Tinea capitis. ***Tinea capitis*** - **Tinea capitis** presents with **patchy hair loss**, **scaling**, and **itching** on the scalp, which are classic signs of a fungal infection. - The fact that the sister also had similar lesions indicates a **contagious** condition, consistent with a **dermatophyte infection**. *Alopecia areata* - Characterized by **sudden, non-scarring hair loss** in circular or oval patches, often with no scaling or inflammation. - It is an **autoimmune condition** and typically not associated with itching or contagiousness amongst siblings. *Pediculosis capitis* - This condition involves an **infestation of head lice**, primarily causing **intense itching** of the scalp. - While it is contagious, it typically presents with **nits** (lice eggs) firmly attached to hair shafts and excoriations from scratching, rather than significant hair loss and scaling. *Pyoderma* - **Pyoderma** is a bacterial skin infection, often presenting as **pustules**, **crusts**, or **blisters** on the scalp. - While it can be contagious and cause discomfort, it is primarily characterized by purulent lesions and not the diffuse patchy hair loss and scaling seen in this case.

Q: A patient presents with annular, scaly plaques with perifollicular extension on the trunk. What is the most likely diagnosis?

Tinea. ***Tinea*** - **Tinea corporis** classically presents with **annular, scaly plaques with central clearing** and an active, raised border. - On hairy areas or with follicular involvement, dermatophyte infections show **perifollicular extension** as the fungus invades hair follicles. - The **annular morphology with scale** is pathognomonic for dermatophyte infection, confirmed by **KOH preparation** showing septate hyphae. - Common sites include trunk, limbs, and any body area with hair follicles. *Psoriasis* - Presents with **well-demarcated, erythematous plaques** with **silvery-white scales**, typically on extensor surfaces (elbows, knees, scalp). - **Follicular psoriasis** is rare and shows **pinpoint follicular papules**, not annular plaques with perifollicular extension. - Auspitz sign (pinpoint bleeding on scale removal) helps differentiate from tinea. *Lichen planus* - Characterized by **pruritic, polygonal, purple, planar papules** (the "6 Ps"). - **Lichen planopilaris** (follicular variant) causes **scarring alopecia** with follicular hyperkeratosis, not annular scaly plaques. - Wickham striae may be visible on mucosal surfaces. *Pityriasis versicolor* - Caused by **Malassezia species**, presents as **hypo- or hyperpigmented macules** with fine scale on trunk and upper arms. - **Follicular variant** (pityriasis folliculorum) shows discrete follicular papules, NOT annular plaques. - "Spaghetti and meatballs" appearance on KOH prep (short hyphae and spores) differentiates from dermatophytes.

Q: A male child presents with a mildly painful swelling on his scalp for the last 3 months, as shown in the image. The history reveals that there is a pet dog in the household. What is the most likely diagnosis?

Kerion. ***Kerion*** - A **kerion** is a severe, inflammatory type of **tinea capitis** (ringworm of the scalp) that presents as a **boggy, tender, swollen mass** with pustules and crusting on the scalp. - The **3-month duration** is consistent with a chronic fungal infection rather than an acute bacterial process. - The presence of a **pet dog** in the household is a critical clue, as **zoophilic dermatophytes** (especially *Microsporum canis* from dogs and cats) are common causes of inflammatory tinea capitis that progresses to kerion. - Kerion typically appears as a soft, elevated, "honeycomb-like" mass with oozing and matting of hair. *Abscess* - An **abscess** is a localized collection of pus from bacterial infection and would typically present with **acute onset**, severe pain, fluctuance, and systemic signs of infection. - The **3-month duration** makes a simple bacterial abscess unlikely, as it would typically evolve more rapidly (days to weeks) and require drainage. - The pet exposure and chronic course favor a fungal etiology over bacterial infection. *Scabies* - **Scabies** is caused by the mite *Sarcoptes scabiei* and presents with **intensely itchy papules, vesicles, and burrows**, typically in intertriginous areas (web spaces, wrists, axillae, groin). - Scalp involvement is rare except in infants with crusted scabies, and it does not present as a solitary, boggy, mildly painful swelling. - The clinical presentation and location do not match scabies. *Folliculitis* - **Folliculitis** is inflammation of hair follicles, usually due to bacterial infection (commonly *Staphylococcus aureus*), presenting as **multiple small, red, tender pustules** centered around hair follicles. - While it can occur on the scalp, folliculitis typically involves **multiple discrete lesions** rather than a single large, confluent, boggy mass. - The presentation would be more acute and superficial, not a deep-seated swelling persisting for 3 months.

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: All the following drugs are effective in the treatment of Pityriasis Versicolor except:

Griseofulvin. ***Griseofulvin*** - **Griseofulvin** is an oral antifungal agent primarily effective against **dermatophytes** (tinea infections) by interfering with microtubule assembly and fungal cell division. - It is **ineffective against *Malassezia furfur***, the yeast responsible for Pityriasis Versicolor, as this organism is not a dermatophyte. *Clotrimazole* - **Clotrimazole** is a topical azole antifungal that inhibits **lanosterol 14-alpha-demethylase**, a crucial enzyme in fungal ergosterol synthesis, making it effective against *Malassezia furfur*. - It works by disrupting the **fungal cell membrane**, leading to its fungistatic and fungicidal properties. *Selenium Sulphide* - **Selenium Sulphide** is a topical antifungal agent that acts as a **cytostatic agent**, reducing the growth rate of epidermal cells and inhibiting the growth of *Malassezia furfur*. - It is commonly used in **shampoos and lotions** for treating Pityriasis Versicolor, often applied as a lather and left on the skin. *Ketoconazole* - **Ketoconazole** is another azole antifungal, available in both topical and oral forms, effective against *Malassezia furfur* by inhibiting **ergosterol synthesis**. - Its broad-spectrum antifungal activity makes it a common and effective treatment for **Pityriasis Versicolor**.

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: 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.

Question 1

A child presents with multiple patchy areas of hair loss, scales, and itching. The sister also had similar lesions. What is the most likely diagnosis?

Accepted Answer

Tinea capitis

Answer

Alopecia areata

Answer

Pediculosis capitis

Answer

Pyoderma

Question 2

A patient presents with annular, scaly plaques with perifollicular extension on the trunk. What is the most likely diagnosis?

Accepted Answer

Tinea

Answer

Psoriasis

Answer

Lichen planus

Answer

Pityriasis versicolor

Question 3

A male child presents with a mildly painful swelling on his scalp for the last 3 months, as shown in the image. The history reveals that there is a pet dog in the household. What is the most likely diagnosis?

Accepted Answer

Kerion

Answer

Abscess

Answer

Scabies

Answer

Folliculitis

Question 4

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 5

All the following drugs are effective in the treatment of Pityriasis Versicolor except:

Accepted Answer

Griseofulvin

Answer

Clotrimazole

Answer

Selenium Sulphide

Answer

Ketoconazole

Question 6

Selenium sulfide is indicated for treating?

Accepted Answer

Tinea versicolor

Answer

Tinea corporis

Answer

Candidiasis only

Answer

Mixed mycotic infections

Question 7

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 8

Hypersensitivity to dermatophyte antigens is called

Accepted Answer

ID reaction

Answer

Frenkel's reaction

Answer

Bachman reaction

Answer

Schultz-Charlton reaction

Question 9

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 10

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

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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