Fungal Skin Infections Practice Questions

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.

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: Which of the following is the location beyond which fungus does not penetrate in tinea capitis ?

Adamson's fringe. ***Adamson's fringe*** - Adamson's fringe is the **critical anatomical boundary** located at the opening of the sebaceous gland duct into the hair follicle. - It represents the zone where **hair keratinization is complete** and marks the transition between the keratinized (dead) upper portion and the living, pre-keratinized hair matrix below. - In tinea capitis, dermatophyte fungi **cannot penetrate beyond Adamson's fringe** because they are keratinophilic organisms that can only invade fully keratinized tissue [1]—they cannot survive in the living hair bulb below this level. - This is the **deepest point of fungal penetration** in the hair follicle. *Isthmus* - The isthmus is the mid-portion of the hair follicle located **between the insertion of the arrector pili muscle and the opening of the sebaceous gland**. - It is **above/superficial to Adamson's fringe**, meaning fungi can and do penetrate through this region as they invade downward toward Adamson's fringe. - Therefore, the isthmus is **not the limiting boundary** of fungal penetration. *Infundibulum* - The infundibulum is the **uppermost segment** of the hair follicle, extending from the skin surface down to the sebaceous gland opening. - This is the **most superficial region** where fungal infection typically begins in tinea capitis. - Fungi are readily present in the infundibulum but penetrate **deeper than this level**, making it not the limiting boundary. *Stem* - "Stem" refers to the **hair shaft itself** (the visible, keratinized hair fiber) rather than a specific anatomical boundary within the follicle. - While fungi do invade the hair stem/shaft, this term does not define the **anatomical limit of penetration within the follicle architecture**—that limit is specifically Adamson's fringe. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 638-639.

Question 1

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 2

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 3

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

Accepted Answer

Griseofulvin

Answer

Clotrimazole

Answer

Selenium Sulphide

Answer

Ketoconazole

Question 4

Selenium sulfide is indicated for treating?

Accepted Answer

Tinea versicolor

Answer

Tinea corporis

Answer

Candidiasis only

Answer

Mixed mycotic infections

Question 5

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 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

Which of the following is the location beyond which fungus does not penetrate in tinea capitis ?

Accepted Answer

Adamson's fringe

Answer

Isthmus

Answer

Infundibulum

Answer

Stem

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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