Fungal Skin Infections — MCQs

Fungal Skin Infections Indian Medical PG Practice Questions and MCQs

Question 91: All of the following are true regarding Tinea versicolor except:

A. Orange fluorescence with Wood lamp examination
B. Caused by Malassezia globosa
C. Griseofulvin is the drug of choice (Correct Answer)
D. Both hypo and hyperpigmented lesions

Explanation: **Explanation:** **Tinea versicolor** (Pityriasis versicolor) is a common superficial fungal infection caused by the lipophilic yeast **Malassezia globosa** (and *M. furfur*). **Why Option C is the correct answer (False statement):** Griseofulvin is **ineffective** in the treatment of Tinea versicolor. Griseofulvin is only active against dermatophytes (Trichophyton, Microsporum, and Epidermophyton) because it requires active keratin uptake, which Malassezia does not perform. The **drug of choice** for localized infection is topical ketoconazole or selenium sulfide; for systemic treatment, oral **Itraconazole** or Fluconazole is preferred. **Analysis of other options:** * **Option A:** Under Wood’s lamp, the lesions typically show a characteristic **golden-yellow or orange fluorescence** due to the presence of pteridine metabolites. * **Option B:** While *M. furfur* was historically cited, **Malassezia globosa** is now recognized as the most common causative agent. * **Option D:** The name "versicolor" refers to the variety of pigmentary changes. It can present as **hypopigmented** (due to azelaic acid production inhibiting melanin) or **hyperpigmented/erythematous** lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** KOH mount shows the classic **"Spaghetti and Meatballs"** appearance (short, thick hyphae and clusters of spores). * **Clinical Sign:** **Besnier’s sign** (or "Coupe d’ongle" sign) – scratching the lesion produces fine, branny scales. * **Culture:** Requires enrichment with lipids (e.g., olive oil) as Malassezia is lipophilic. * **Risk Factors:** High humidity, excessive sweating, and oily skin.

Question 92: Kerion is caused by?

A. Candida
B. Streptococcus
C. Dermatophytes (Correct Answer)
D. Herpes

Explanation: **Explanation:** **Kerion** is a severe, inflammatory form of **Tinea Capitis** (fungal infection of the scalp). It is caused by a delayed-type hypersensitivity reaction to **Dermatophytes**, most commonly zoophilic species like *Trichophyton verrucosum* (from cattle) or *Trichophyton mentagrophytes*. 1. **Why Dermatophytes is correct:** Kerion presents as a painful, boggy, inflammatory mass studded with pustules. The underlying mechanism is an intense immune response to the dermatophyte fungus infecting the hair follicles. If left untreated, it leads to **cicatricial (scarring) alopecia**. 2. **Why other options are incorrect:** * **Candida:** Causes candidiasis (e.g., oral thrush, intertrigo, or diaper dermatitis), but it does not cause the specific inflammatory boggy swelling known as Kerion. * **Streptococcus:** This is a bacterium. While it can cause skin infections like impetigo or cellulitis, Kerion is primarily a fungal pathology (though secondary bacterial infection can occur). * **Herpes:** This is a viral infection (HSV) causing grouped vesicles on an erythematous base (e.g., herpes labialis), not a deep inflammatory scalp mass. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Sign:** The **"Lustreless hair"** or "Black dot" appearance may precede Kerion. * **Lymphadenopathy:** Painful regional (occipital or cervical) lymphadenopathy is a common associated finding. * **Treatment of Choice:** Systemic antifungal therapy is mandatory. **Oral Griseofulvin** remains the gold standard for Tinea Capitis/Kerion. * **Differential Diagnosis:** Often misdiagnosed as a bacterial abscess; however, incision and drainage should be avoided as it is an inflammatory fungal reaction, not a simple pyogenic collection.

Question 93: Griseofulvin is given for the treatment of onychomycosis of fingernails for what duration?

A. 2 weeks
B. 6 weeks
C. 2 months
D. 6 months (Correct Answer)

Explanation: **Explanation:** The duration of treatment for onychomycosis (fungal infection of the nails) is dictated by the **rate of nail growth**. Griseofulvin is a fungistatic agent that binds to keratin precursor cells, making them resistant to fungal invasion. For the treatment to be successful, the drug must be present until the infected nail is completely replaced by healthy nail tissue. * **Fingernails** grow at an average rate of 3 mm/month and take approximately **4 to 6 months** to fully regrow. Therefore, 6 months is the standard duration for Griseofulvin therapy in fingernail onychomycosis. * **Toenails** grow much slower (1 mm/month) and require a longer treatment duration, typically **12 to 18 months**. **Analysis of Incorrect Options:** * **A & B (2 weeks / 6 weeks):** These durations are far too short for nail infections. Such durations are typically used for superficial skin infections like Tinea corporis or Tinea cruris. * **C (2 months):** While 2 months (8 weeks) is the standard duration for newer fungicidal drugs like **Terbinafine** (for fingernails), it is insufficient for the slower-acting Griseofulvin. **High-Yield Pearls for NEET-PG:** 1. **Mechanism of Action:** Griseofulvin inhibits fungal mitosis by disrupting **mitotic spindles** (microtubule function). 2. **Absorption:** It is highly insoluble; absorption is significantly enhanced when taken with a **fatty meal**. 3. **Drug of Choice (DOC):** While Griseofulvin was the historical DOC, **Terbinafine** is now the preferred first-line agent for onychomycosis due to higher cure rates and shorter treatment cycles (6 weeks for fingernails, 12 weeks for toenails). 4. **Side Effects:** Headache is the most common; it can also cause photosensitivity and disulfiram-like reactions.

Question 94: White piedra is caused by which of the following fungi?

A. Piedraia hortae
B. Malassezia globosa
C. Hortaea werneckii
D. Trichosporon beigelii (Correct Answer)

Explanation: **Explanation:** **White Piedra** is a superficial fungal infection of the hair shaft characterized by soft, white to light brown nodules. The correct answer is **Trichosporon beigelii** (now often reclassified as *Trichosporon asahii* or other *Trichosporon* species). These nodules are loosely attached to the hair shaft and are composed of hyphae and blastoconidia. It primarily affects the hair of the beard, mustache, and pubic area. **Analysis of Options:** * **A. Piedraia hortae:** This is the causative agent of **Black Piedra**. Unlike white piedra, it produces hard, black, firmly adherent nodules, typically on the scalp hair. * **B. Malassezia globosa:** This lipophilic yeast is the most common cause of **Pityriasis versicolor** (Tinea versicolor), characterized by hypo- or hyperpigmented scaly macules on the trunk. * **C. Hortaea werneckii:** This is the causative agent of **Tinea nigra**, a superficial infection presenting as dark, brownish-black macules on the palms and soles. **NEET-PG High-Yield Pearls:** * **Diagnosis:** Microscopic examination (KOH mount) of white piedra shows transparent hyphae and **arthroconidia**. * **Treatment:** The treatment of choice for both types of Piedra is shaving or cutting the hair. Topical antifungals (azoles) can also be used. * **Differential:** Do not confuse Piedra with **Pediculosis capitis** (nits are oval and on one side of the shaft) or **Trichomycosis axillaris** (caused by *Corynebacterium*, not a fungus). * **Key Distinction:** White Piedra = Soft/Loose/Trichosporon; Black Piedra = Hard/Adherent/Piedraia.

Question 95: Tinea infection that presents with altered morphology after treatment with a topical steroid is known as:

A. Tinea incognito (Correct Answer)
B. Vagabond disease
C. Tinea versicolor
D. Tinea capitis

Explanation: ### Explanation **Correct Answer: A. Tinea incognito** **Tinea incognito** refers to a dermatophyte infection that has lost its typical clinical features—such as the classic annular shape and well-defined scaly borders—due to the application of **topical corticosteroids**. * **Mechanism:** Steroids suppress the local inflammatory response and cell-mediated immunity. While this temporarily reduces itching and redness, it allows the fungus to proliferate unchecked in the deeper layers of the skin. * **Clinical Presentation:** The lesion becomes "masked," appearing as diffuse erythema, pustules, or even mimicking eczema or psoriasis, making clinical diagnosis difficult. **Why other options are incorrect:** * **B. Vagabond disease:** Also known as *Parasitosis corporis*, this is a condition seen in neglected, malnourished individuals with chronic body lice infestation, leading to generalized hyperpigmentation and thickening of the skin. * **C. Tinea versicolor:** A superficial fungal infection caused by *Malassezia furfur*. It presents as hypo- or hyperpigmented macules with fine scaling (spaghetti and meatball appearance on KOH) and is not defined by steroid modification. * **D. Tinea capitis:** A fungal infection of the scalp and hair shafts, primarily seen in children. While it can be misdiagnosed, the term for steroid-modified tinea is specifically "incognito." **NEET-PG High-Yield Pearls:** * **KOH Mount:** The gold standard for rapid diagnosis; even in Tinea incognito, fungal hyphae remain visible under microscopy. * **Common Culprit:** Often occurs when patients use over-the-counter "triple action" creams (steroid + antifungal + antibacterial). * **Treatment:** Immediate cessation of steroids and initiation of appropriate systemic antifungals (e.g., Terbinafine or Itraconazole).

Question 96: What is the DOC for Tinea Unguium?

A. Amphotericin B
B. Miconazole
C. Grisiofulvin (Correct Answer)
D. Nystatin

Explanation: **Explanation:** **Tinea Unguium** (Onychomycosis) refers to a dermatophytic infection of the nail plate. Because the infection resides deep within the keratinized structure of the nail, topical treatments often fail to penetrate effectively, making **systemic (oral) therapy** the mainstay of treatment. **Why Griseofulvin is the correct answer:** Griseofulvin is a fungistatic drug that binds to tubulin, interfering with microtubule function and inhibiting mitosis. Its unique clinical property is that it **selectively deposits in newly formed keratin** (skin, hair, and nails), making it highly effective for dermatophytoses. While newer drugs like Terbinafine are now clinically preferred due to shorter treatment durations, Griseofulvin remains a classic "Drug of Choice" (DOC) in traditional medical examinations for fungal infections of the keratinized tissues. **Analysis of Incorrect Options:** * **Amphotericin B:** A potent polyene antifungal used for systemic, life-threatening deep mycoses (e.g., Mucormycosis, Visceral Leishmaniasis). It is not used for superficial dermatophytoses due to its toxicity and lack of efficacy in keratin. * **Miconazole:** An imidazole primarily used **topically** for skin infections (Tinea corporis/pedis). It does not achieve therapeutic concentrations in the nail plate when taken orally. * **Nystatin:** A polyene antifungal effective only against **Candida** species. It is not absorbed from the GI tract and is ineffective against dermatophytes. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** While Griseofulvin is the traditional answer, **Terbinafine** is currently the clinical DOC for Onychomycosis due to higher cure rates and shorter duration (6 weeks for fingers, 12 weeks for toes). * **Griseofulvin Side Effect:** Most common is **headache**; it also causes a Disulfiram-like reaction with alcohol. * **Absorption:** Griseofulvin absorption is significantly increased when taken with a **fatty meal**.

Question 97: Tinea versicolor is typically associated with which organism?

A. Pityrosporum orbiculare (Correct Answer)
B. Candida infection
C. Epidermophyton
D. Trichophyton

Explanation: **Explanation:** **Tinea versicolor** (also known as Pityriasis versicolor) is a common superficial fungal infection caused by the overgrowth of **Malassezia furfur**, a lipophilic yeast. Historically, the round yeast forms found on the skin were named ***Pityrosporum orbiculare***, while the oval forms were called *Pityrosporum ovale*. Therefore, *Pityrosporum orbiculare* is the correct mycological designation for the causative agent in this context. **Analysis of Incorrect Options:** * **B. Candida infection:** Causes Candidiasis, typically presenting as erythematous plaques with characteristic "satellite lesions" in intertriginous areas (e.g., diaper dermatitis, intertrigo), not the scaly hypo/hyperpigmented macules of Tinea versicolor. * **C. Epidermophyton:** This is a genus of dermatophytes (e.g., *E. floccosum*) that causes infections like Tinea cruris and Tinea pedis. Unlike Malassezia, dermatophytes invade keratinized tissue. * **D. Trichophyton:** The most common genus of dermatophytes (e.g., *T. rubrum*). It is responsible for most cases of Tinea corporis, Tinea capitis, and onychomycosis. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** KOH mount shows the classic **"Spaghetti and Meatballs"** appearance (short, blunt hyphae and thick-walled budding spores). * **Wood’s Lamp:** Lesions emit a characteristic **yellowish-gold or pale orange fluorescence**. * **Clinical Sign:** **Selisky’s Sign** (Evoked Scale) – scraping the lesion produces fine, branny scales (furfuraceous). * **Treatment:** Topical antifungals like Ketoconazole or Selenium sulfide are first-line. Oral Fluconazole is used for extensive cases.

Question 98: Which of the following is NOT a treatment for Pityriasis versicolor?

A. Ketoconazole
B. Griseofulvin (Correct Answer)
C. Clotrimazole
D. Selenium sulphate

Explanation: **Explanation:** **Pityriasis versicolor** (Tinea versicolor) is a superficial fungal infection caused by the lipophilic yeast **Malassezia furfur**. Because the fungus resides in the uppermost layer of the skin (stratum corneum) and is not a dermatophyte, the choice of antifungal therapy is specific. **Why Griseofulvin is the Correct Answer:** Griseofulvin is an oral antifungal agent that is highly effective against **dermatophytes** (Trichophyton, Microsporum, and Epidermophyton) because it binds to keratin precursor cells. However, it is **ineffective** against Malassezia species, Candida, and deep mycoses. Therefore, it has no role in the treatment of Pityriasis versicolor. **Analysis of Other Options:** * **Ketoconazole (Option A):** An azole antifungal that is the gold standard for Malassezia. It can be used topically (shampoo/cream) or orally for extensive cases. * **Clotrimazole (Option B):** A topical imidazole that is effective against a broad spectrum of fungi, including Malassezia. * **Selenium sulphide (Option D):** A cytostatic agent often used as a 2.5% lotion or shampoo. It works by reducing the turnover of the stratum corneum and has direct sporicidal activity against Malassezia. **High-Yield Clinical Pearls for NEET-PG:** * **Causative Agent:** *Malassezia furfur* (formerly Pityrosporum ovale). * **Microscopy:** Classic **"Spaghetti and Meatball"** appearance (hyphae and spores) on KOH mount. * **Wood’s Lamp:** Shows a characteristic **Golden-yellow/Pale-yellow fluorescence**. * **Clinical Sign:** **Besnier’s sign** (Scratch sign) – scaling becomes more apparent upon scratching the lesion. * **First-line Treatment:** Topical azoles or Selenium sulphide. Oral Fluconazole or Itraconazole are used for recurrent or extensive disease.

Question 99: A 40-year-old male presents with a rash over the groin characterized by demarcated peripheral scaling and central clearing. What is the most likely cause?

A. Candidiasis
B. Malassezia furfur
C. Trichophyton (Correct Answer)
D. Aspergillosis

Explanation: **Explanation:** The clinical presentation of a well-demarcated rash in the groin with **peripheral scaling and central clearing** is the hallmark of **Tinea cruris** (a dermatophytosis). 1. **Why Trichophyton is correct:** Dermatophytes (Trichophyton, Microsporum, and Epidermophyton) are keratinophilic fungi that invade the stratum corneum. They spread centrifugally, resulting in an active, scaly border where the fungus is most active, while the center heals, creating the classic "ringworm" or annular appearance. **Trichophyton rubrum** is the most common causative agent of Tinea cruris worldwide. 2. **Why other options are incorrect:** * **Candidiasis:** Typically presents as a beefy red erythematous plaque with **satellite lesions** (pustules/papules) and lacks central clearing. It often involves the scrotum (unlike Tinea cruris, which usually spares it). * **Malassezia furfur:** Causes Pityriasis versicolor, characterized by hypo- or hyperpigmented macules with fine (branny) scaling, usually on the trunk, not typically presenting with annular lesions in the groin. * **Aspergillosis:** Primarily a systemic or opportunistic deep fungal infection; it does not cause superficial annular skin lesions like Tinea. **High-Yield Clinical Pearls for NEET-PG:** * **Tinea Cruris:** Often spares the scrotum and penis (helps differentiate from Candidiasis). * **Diagnosis:** KOH mount shows **septate branching hyphae**. * **Treatment of choice:** Topical or systemic **Azoles** or **Terbinafine**. * **Majocchi’s Granuloma:** A deep dermatophyte infection of the hair follicle, often caused by *T. rubrum*.

Question 100: The 'hanging curtain' sign is seen in which of the following conditions?

A. Pityriasis rosea (Correct Answer)
B. Pityriasis versicolor
C. Pityriasis rubra pilaris
D. Pityriasis lichenoides chronica

Explanation: **Explanation:** The **'Hanging Curtain' sign** (also known as the 'curtain sign') is a characteristic clinical feature of **Pityriasis Rosea (PR)**. When the skin of a PR lesion is stretched perpendicular to the long axis of the oval plaque, the fine, cigarette-paper-like scales remain attached at the periphery but fold inward, resembling a hanging curtain. **Why the correct answer is right:** Pityriasis Rosea is an acute, self-limiting inflammatory dermatosis (likely associated with HHV-6 and HHV-7). It typically begins with a **Herald Patch**, followed by a generalized eruption of oval, salmon-colored plaques. These plaques feature a characteristic **collarette of scales** (scales attached at the edges, pointing inward). The "hanging curtain" sign specifically demonstrates the unique attachment and fragility of these scales during physical examination. **Why the incorrect options are wrong:** * **Pityriasis versicolor:** Caused by *Malassezia furfur*, it is characterized by the **'Besnier’s sign'** or 'Coup d’ongle' sign (scaling produced by scraping the lesion with a fingernail). * **Pityriasis rubra pilaris (PRP):** Characterized by follicular papules on an erythematous base, "islands of sparing," and orange-red palmoplantar keratoderma. It does not exhibit the curtain sign. * **Pityriasis lichenoides chronica:** Presents with asymptomatic, brownish-pink papules with a "frosted glass" or **'mica-like' scale** that can be peeled off in one piece. **High-Yield Clinical Pearls for NEET-PG:** * **Herald Patch:** The initial, largest lesion (usually on the trunk). * **Christmas Tree Pattern:** Lesions follow the lines of cleavage (Langer’s lines). * **Collarette of scales:** Scales are attached peripherally and free centrally. * **Treatment:** Reassurance; it is self-limiting (6–8 weeks). Acyclovir may reduce duration if started early.

Practice by Chapter

Dermatophytoses

Practice Questions

Tinea Versicolor

Practice Questions

Candidiasis

Practice Questions

Onychomycosis

Practice Questions

Subcutaneous Mycoses

Practice Questions

Systemic Mycoses with Cutaneous Manifestations

Practice Questions

Opportunistic Fungal Infections

Practice Questions

Mycetoma

Practice Questions

Tropical Fungal Infections

Practice Questions

Diagnosis of Fungal Infections

Practice Questions

Antifungal Therapy

Practice Questions

Preventive Strategies

Practice Questions

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