Fungal Skin Infections Practice Questions

Q: A 12-year-old boy presents with a boggy swelling and easily pluckable hair. What is the probable diagnosis?

Tinea capitis. ### Explanation **Correct Answer: B. Tinea capitis** The clinical presentation of a **boggy, inflammatory swelling** with **easily pluckable hair** is the classic description of a **Kerion**, which is a severe inflammatory form of **Tinea capitis**. * **Pathophysiology:** Tinea capitis is a dermatophyte infection of the scalp, most common in children. A Kerion represents a delayed-type hypersensitivity reaction to the fungus (commonly *Trichophyton verrucosum* or *T. mentagrophytes*). * **Clinical Features:** The "boggy" nature refers to the soft, pus-filled, abscess-like consistency. Hair follicles are damaged by the intense inflammation, leading to hair that can be pulled out without pain (easily pluckable). **Why other options are incorrect:** * **Lichen planus:** Specifically, Lichen Planopilaris causes scarring alopecia with perifollicular scaling and erythema, but it does not present as a boggy, acute inflammatory mass. * **Epidermophytosis:** While *Epidermophyton* is a dermatophyte, it typically affects the skin (Tinea corporis/cruris) and nails, but **never** infects the hair. * **Alopecia areata:** This presents as non-scarring, non-inflammatory smooth patches of hair loss. The characteristic finding is "exclamation mark hair," not a boggy swelling. **High-Yield NEET-PG Pearls:** 1. **Kerion Management:** Do **not** incise and drain (it is not a bacterial abscess). Treat with systemic antifungals (Griseofulvin is the gold standard) and sometimes oral steroids to reduce scarring. 2. **Black Dot Tinea:** Caused by endothrix organisms (e.g., *T. tonsurans*); hair breaks at the surface. 3. **Favus:** Caused by *T. schoenleinii*; characterized by **scutula** (cup-shaped crusts) and a "mousy odor." 4. **Wood’s Lamp:** *Microsporum* species show a brilliant green fluorescence, while most *Trichophyton* species (except *T. schoenleinii*) do not fluoresce.

Q: Which of the following statements about pityriasis versicolor is FALSE?

Corticosteroids are used in its treatment.. ### Explanation **Pityriasis Versicolor (Tinea Versicolor)** is a superficial fungal infection caused by the lipophilic yeast *Malassezia*. **Why Option D is the Correct (False) Statement:** Corticosteroids are **contraindicated** in fungal infections. They are immunosuppressive agents that can worsen the infection, lead to its spread, or mask symptoms (Tinea Incognito). The mainstay of treatment for Pityriasis Versicolor includes **topical antifungals** (e.g., Ketoconazole shampoo, Ciclopirox olamine) or oral antifungals (e.g., Fluconazole, Itraconazole) for extensive cases. **Analysis of Other Options:** * **Option A:** While *Malassezia furfur* was historically cited, **_Malassezia globosa_** is now recognized as the most common causative agent. * **Option B:** A KOH mount of skin scrapings reveals short, thick hyphae and clusters of spores, classically described as a **"spaghetti and meatball"** or "banana and grapes" appearance. * **Option C:** *Malassezia* is lipophilic and requires the addition of olive oil to SDA for growth. The resulting colonies are creamy/yellowish and often exhibit a characteristic **"fried egg"** morphology. **High-Yield Clinical Pearls for NEET-PG:** * **Wood’s Lamp Examination:** Shows a characteristic **yellowish-gold or pale-yellow fluorescence**. * **Clinical Presentation:** Hypopigmented or hyperpigmented macules with fine scaling (**Besnier’s sign** or "scratch sign"—scaling becomes visible upon scratching the lesion). * **Pathogenesis:** The hypopigmentation is due to **azelaic acid** produced by the fungus, which inhibits tyrosinase, thereby interfering with melanin synthesis. * **Common Site:** Upper trunk and back (seborrheic areas).

Q: The 'spaghetti and meatballs' appearance on microscopy is characteristic of which dermatological condition?

Tinea versicolor. **Explanation:** The "spaghetti and meatballs" appearance is a classic histopathological description for **Tinea versicolor** (also known as Pityriasis versicolor). This appearance is seen on a **KOH (Potassium Hydroxide) mount** of skin scrapings. * **The Concept:** Tinea versicolor is caused by the lipophilic yeast ***Malassezia furfur***. Under the microscope, the "spaghetti" represents the short, thick, blunt **hyphae**, while the "meatballs" represent the clusters of **spherical yeast cells** (spores). **Analysis of Incorrect Options:** * **Pityriasis rosea:** This is an inflammatory condition characterized by a "Herald patch" and a "Christmas tree" distribution. It is not fungal; microscopy shows non-specific features like parakeratosis and spongiosis. * **Tinea capitis & Tinea corporis:** These are true dermatophyte infections (e.g., *Trichophyton*, *Microsporum*). On KOH mount, they typically show **branching, septate hyphae** without the characteristic globular yeast clusters seen in *Malassezia*. **Clinical Pearls for NEET-PG:** * **Wood’s Lamp:** Tinea versicolor shows a characteristic **yellowish-gold or pale-orange fluorescence**. * **Clinical Sign:** **Besnier’s sign** (or the "scratch sign")—scaling becomes more apparent when the lesion is stroked with a finger or curette. * **Appearance:** Presents as hypo- or hyperpigmented macules with fine scaling (pityriasis), usually on the chest and back. * **Culture:** If required, *Malassezia* requires media enriched with lipids (e.g., **Dixon’s agar** or olive oil overlay on SDA).

Q: An 8-year-old boy presents with a boggy scalp swelling and easily pluckable hair. Which of the following is the investigation of choice?

KOH smear. ### Explanation **Diagnosis: Kerion (Inflammatory Tinea Capitis)** The clinical presentation of a **boggy, painful scalp swelling** with **easily pluckable hair** and associated lymphadenopathy is classic for **Kerion**. This is a severe inflammatory cell-mediated immune response to a dermatophyte infection (most commonly *Trichophyton mentagrophytes* or *T. verrucosum*). **Why KOH Smear is the Correct Answer:** * **Investigation of Choice:** In any suspected fungal infection of the skin, hair, or nails, a **10%–20% KOH (Potassium Hydroxide) smear** is the initial and most important investigation. * **Mechanism:** KOH dissolves keratin, allowing the visualization of fungal elements. In Kerion, microscopic examination of the plucked hair will show fungal hyphae or spores (ectothrix or endothrix invasion), confirming the dermatophytic origin. **Why Other Options are Incorrect:** * **A. Biopsy:** Rarely indicated for tinea capitis. It is invasive and usually reserved for cases where inflammatory conditions like discoid lupus or lichen planopilaris are suspected. * **B. X-ray Skull:** Kerion is a soft tissue fungal infection; it does not involve the bone. X-rays have no diagnostic value here. * **D. Tzanck Smear:** This is used for the rapid diagnosis of **Herpes Simplex or Varicella-Zoster** (looking for multinucleated giant cells), not fungal infections. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment:** Oral **Griseofulvin** is the gold standard for Tinea Capitis (Kerion). Topical antifungals are ineffective as they do not penetrate the hair follicle. * **Complication:** If untreated, Kerion leads to **cicatricial (permanent) alopecia**. * **Wood’s Lamp:** Useful for screening; *Microsporum* species show a brilliant green fluorescence, while most *Trichophyton* species (common in Kerion) do not fluoresce.

Q: Tinea capitis is caused by which of the following fungi, except?

Epidermophyton. **Explanation:** The correct answer is **Epidermophyton**. Dermatophytes are classified into three genera based on their tissue predilection: *Trichophyton*, *Microsporum*, and *Epidermophyton*. The genus **Epidermophyton** (specifically *E. floccosum*) is unique because it infects only the **skin and nails**. It lacks the ability to invade hair follicles; therefore, it **never causes Tinea capitis**. **Analysis of Options:** * **Microsporum (Option B):** This genus infects both **hair and skin**. It is a common cause of ectothrix infections (where spores form on the outside of the hair shaft) and often presents with fluorescence under Wood’s lamp. * **Trichophyton violaceum (Option C):** This is a classic cause of **Endothrix** Tinea capitis (spores inside the hair shaft), leading to "Black Dot" Tinea capitis due to hair breakage at the surface. * **Trichophyton schoenleinii (Option D):** This is the primary causative agent of **Tinea favosa (Favus)**, characterized by yellowish cup-shaped crusts called scutula and permanent scarring alopecia. **High-Yield NEET-PG Pearls:** 1. **Rule of Three:** * *Trichophyton:* Infects Skin, Hair, and Nails. * *Microsporum:* Infects Skin and Hair (NOT nails). * *Epidermophyton:* Infects Skin and Nails (NOT hair). 2. **Most common cause of Tinea capitis worldwide:** *Trichophyton tonsurans*. 3. **Wood’s Lamp:** *Microsporum* species typically fluoresce (bright green), while most *Trichophyton* species (except *T. schoenleinii*) do not. 4. **Ectothrix vs. Endothrix:** Endothrix (e.g., *T. violaceum*) results in "Black dots"; Ectothrix (e.g., *Microsporum*) results in "Grey patches."

Q: Kerion is a type of:

Fungal infection. **Explanation:** **Kerion** is a highly inflammatory, boggy, and painful swelling of the scalp. It represents a severe **delayed-type hypersensitivity reaction (Type IV)** to a dermatophyte infection, most commonly caused by zoophilic species like *Trichophyton mentagrophytes* or *Trichophyton verrucosum*. It is a clinical variant of **Tinea Capitis**. * **Why Option D is Correct:** Kerion is a fungal infection. It occurs when the body reacts intensely to the fungal antigens, leading to an inflammatory mass studded with pustules and "honeycomb" crusting. If left untreated, it can lead to permanent scarring (cicatricial) alopecia. * **Why Options A, B, and C are Incorrect:** * **Bacterial (A):** While Kerion may resemble a bacterial abscess or carbuncle, it is primarily fungal. Secondary bacterial infection can occur, but the etiology is dermatophytic. * **Prion (B):** Prion diseases (like Creutzfeldt-Jakob disease) are neurodegenerative disorders caused by misfolded proteins, unrelated to skin pathology. * **Viral (C):** Viral skin infections (like Herpes or Molluscum) present with vesicles or umbilicated papules, not boggy inflammatory masses. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Sign:** The **"Lustreless hair"** sign and easily pluckable hair are characteristic. * **Diagnosis:** KOH mount shows fungal hyphae/spores; Wood’s lamp may show fluorescence depending on the species. * **Management:** Oral **Griseofulvin** is the gold standard (DOC) for Tinea Capitis. Systemic steroids are often added to reduce inflammation and prevent scarring alopecia. * **Differential Diagnosis:** Always differentiate from a bacterial carbuncle; a Kerion is usually less painful than its appearance suggests and does not respond to antibiotics alone.

Q: Dermatophytoses is caused by which of the following organisms?

Trichophyton. **Explanation:** **Dermatophytoses** (commonly known as Tinea or Ringworm) are fungal infections of the keratinized tissues, including the skin, hair, and nails. They are caused by a specific group of fungi called **Dermatophytes**, which have the unique ability to metabolize keratin using the enzyme keratinase. 1. **Why Trichophyton is correct:** Dermatophytes are classified into three genera: **Trichophyton**, **Microsporum**, and **Epidermophyton**. *Trichophyton* is the most common genus and is responsible for infecting skin, hair, and nails (e.g., *T. rubrum* is the most common cause of Tinea corporis and Tinea pedis worldwide). 2. **Why other options are incorrect:** * **Herpes simplex:** This is a DNA virus causing vesicular eruptions (Cold sores/Genital herpes), not a fungus. * **Papillomavirus (HPV):** This virus causes various types of warts (Verruca) and is associated with cervical cancer. * **Candida:** While *Candida* is a fungus (yeast), it is not a dermatophyte. It causes **Candidiasis**, which typically involves mucosal surfaces and intertriginous areas (skin folds) and is characterized by "satellite lesions," which are absent in dermatophytosis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common dermatophyte worldwide:** *Trichophyton rubrum*. * **Tinea Capitis:** Most common cause in children; *T. tonsurans* (non-fluorescent) is common in the US, while *M. audouinii* (fluorescent) was historically significant. * **Diagnosis:** The gold standard for screening is **KOH mount**, which shows branching septate hyphae. Culture is done on **Sabouraud’s Dextrose Agar (SDA)**. * **Wood’s Lamp:** Microsporum species show a bright green fluorescence, whereas most Trichophyton species (except *T. schoenleinii*) do not fluoresce.

Q: Which structures can be infected by Trichophyton species?

Skin, hair, and nails. ### Explanation The correct answer is **A. Skin, hair, and nails.** **1. Underlying Medical Concept** Dermatophytes are a group of fungi that require keratin for growth and are classified into three genera based on the structures they infect: **Trichophyton, Microsporum, and Epidermophyton.** * **Trichophyton** is the most versatile genus; it possesses proteolytic enzymes (keratinases) capable of breaking down keratin in all three keratinized tissues: **skin, hair, and nails.** * Common species include *T. rubrum* (the most common cause of dermatophytosis worldwide) and *T. mentagrophytes*. **2. Analysis of Incorrect Options** * **Option B (Skin and nails):** This pattern is characteristic of **Epidermophyton** (specifically *E. floccosum*). It notably **does not** infect hair. * **Option C & D:** These are incomplete. While Trichophyton *can* infect these structures, it is not limited to them. **Microsporum** species typically infect **skin and hair**, rarely involving the nails. **3. Clinical Pearls for NEET-PG** To remember the tissue tropism, use this high-yield table: | Genus | Skin | Hair | Nails | | :--- | :---: | :---: | :---: | | **Trichophyton** | Yes | Yes | Yes | | **Microsporum** | Yes | Yes | No (Rarely) | | **Epidermophyton**| Yes | No | Yes | * **Mnemonic:** *Trichophyton* = "Tri" (infects all 3). *Epidermophyton* = "No Hair" (E**p**idermophyton lacks **p**ilary involvement). * **Wood’s Lamp:** *Microsporum* species often show bright green fluorescence, whereas most *Trichophyton* species (except *T. schoenleinii*) do not fluoresce. * **T. rubrum** is the most common cause of Tinea pedis, Tinea cruris, and Onychomycosis.

Question 1

A 12-year-old boy presents with a boggy swelling and easily pluckable hair. What is the probable diagnosis?

Accepted Answer

Tinea capitis

Answer

Lichen planus

Answer

Epidermophytosis

Answer

Alopecia areata

Question 2

Which of the following statements about pityriasis versicolor is FALSE?

Accepted Answer

Corticosteroids are used in its treatment.

Answer

It is caused by Malassezia globosa.

Answer

It shows a 'spaghetti and meatball' appearance on KOH mount.

Answer

Fungal colonies on Sabouraud Dextrose Agar (SDA) have a 'fried egg' appearance.

Question 3

The 'spaghetti and meatballs' appearance on microscopy is characteristic of which dermatological condition?

Accepted Answer

Tinea versicolor

Answer

Pityriasis rosea

Answer

Tinea capitis

Answer

Tinea corporis

Question 4

What is the most common organism causing Tinea capitis?

Accepted Answer

Microsporum

Answer

Trichophyton tonsurans

Answer

Epidermophyton

Answer

Candida albicans

Question 5

Which of the following is NOT a true statement regarding Tinea capitis?

Accepted Answer

It is characterized by the presence of dark brown to black nodules cemented to the hair shaft.

Answer

It is a form of Tinea capitis.

Answer

It is caused by Tinea schoenlein.

Answer

It causes cicatricial alopecia.

Question 6

An 8-year-old boy presents with a boggy scalp swelling and easily pluckable hair. Which of the following is the investigation of choice?

Accepted Answer

KOH smear

Answer

Biopsy

Answer

X-ray skull

Answer

Tzank smear

Question 7

Tinea capitis is caused by which of the following fungi, except?

Accepted Answer

Epidermophyton

Answer

Microsporum

Answer

Trichophyton violaceum

Answer

Trichophyton schoenleinii

Question 8

Kerion is a type of:

Accepted Answer

Fungal infection

Answer

Bacterial infection

Answer

Prion disease

Answer

Viral infection

Question 9

Dermatophytoses is caused by which of the following organisms?

Accepted Answer

Trichophyton

Answer

Herpes simplex

Answer

Papillomavirus

Answer

Candida

Question 10

Which structures can be infected by Trichophyton species?

Accepted Answer

Skin, hair, and nails

Answer

Skin and nails

Answer

Hair and nails

Answer

Skin and hair

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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