Fungal Skin Infections Practice Questions

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

Tinea incognito. ### 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).

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

Griseofulvin. **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.

Q: 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?

Trichophyton. **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*.

Q: Vesicular lesions, indistinguishable from primary infection, which arise in other parts of the body of an allergic individual infected with Trichophyton are referred to as?

Dermatiphytids. ### Explanation **Correct Option: A. Dermatiphytids** Dermatiphytids (or **'id' reactions**) are secondary inflammatory eruptions that occur in sensitized individuals as an allergic response to a primary fungal infection (usually a dermatophyte like *Trichophyton*). * **Mechanism:** These lesions represent a **Type IV hypersensitivity reaction** to fungal antigens circulating in the blood. * **Key Feature:** The lesions are **sterile** (fungus cannot be cultured from the 'id' site) and often appear as itchy vesicles on the hands or trunk, distant from the primary site of infection (e.g., *Tinea pedis*). They resolve only when the primary focus of infection is treated. **Analysis of Incorrect Options:** * **B. Trichophytins:** This refers to the crude antigen extract derived from *Trichophyton* species used in skin testing to detect delayed-type hypersensitivity. It is a diagnostic tool, not the clinical lesion itself. * **C. Eschars:** An eschar is a dry, dark scab or falling away of dead skin, typically seen in cutaneous anthrax, scrub typhus, or certain fungal infections like Mucormycosis. It is necrotic tissue, not an allergic reaction. * **D. Carbuncles:** A carbuncle is a cluster of interconnected furuncles (boils) caused by a bacterial infection, most commonly *Staphylococcus aureus*. It involves deep suppuration of the hair follicles. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The "id" reaction is diagnosed by the triad of: a proven primary fungal focus, sterile secondary lesions, and resolution after treating the primary site. * **Common Presentation:** The most frequent presentation is a **vesicular eruption on the sides of the fingers** associated with inflammatory *Tinea pedis* (Athlete's foot). * **Dermatophytes:** Remember the three genera: *Trichophyton* (infects hair, skin, nails), *Microsporum* (hair, skin), and *Epidermophyton* (skin, nails).

Q: A patient with asymptomatic annular skin lesion as shown presents to OPD. Which investigation should be done?

KOH mount. ***KOH mount*** - The image displays a classic **annular (ring-shaped) lesion** with a raised, erythematous, and scaly border with central clearing, which is pathognomonic for **Tinea corporis** (ringworm). - A **KOH mount** is the gold standard, rapid, and cost-effective diagnostic test for dermatophytosis, allowing visualization of **septate hyphae** from skin scrapings. ***HIV testing*** - While widespread or severe fungal infections can be associated with **immunocompromised states** like HIV, it is not the initial diagnostic step for a localized lesion. - This test would be considered only if the infection is unusually persistent, recurrent, or if there are other systemic signs suggesting immunosuppression. ***Biopsy*** - A **skin biopsy** is an invasive procedure and is not the first-line investigation for a typical presentation of tinea corporis. - It is reserved for atypical cases or when the diagnosis is uncertain after non-invasive tests, to rule out other annular dermatoses like **granuloma annulare** or **psoriasis**. ***Chest X-ray*** - A **Chest X-ray** is indicated for evaluating cardiopulmonary conditions and has no diagnostic value for a cutaneous fungal infection. - This investigation is entirely unrelated to the patient's presenting skin lesion.

Q: A carpenter presents with a nodule on dorsum of hand which ulcerates after few days and has not healed for last 2 months. Biopsy of lesion was performed and shown below. All are used in management of this condition except:

Cotrimoxazole. ***Cotrimoxazole*** - Cotrimoxazole (trimethoprim-sulfamethoxazole) is an **antibiotic** and is **not indicated** for the treatment of **sporotrichosis**, which is a fungal infection. - The image shows budding yeasts and cigar-shaped forms typical of **Sporothrix schenckii**, alongside a giant cell, confirming a fungal etiology. - Cotrimoxazole is used for bacterial infections and has **no antifungal activity**. *Saturated solution of potassium iodide (SSKI)* - **SSKI** is a traditional and highly effective treatment for **cutaneous and lymphocutaneous sporotrichosis**. - It works by an unknown mechanism, possibly affecting the fungus directly or enhancing the host's immune response. - Particularly useful in **resource-limited settings** due to low cost and good efficacy. *Itraconazole* - **Itraconazole** is the **first-line drug of choice** for treating **cutaneous, lymphocutaneous, and disseminated sporotrichosis**. - It is a broad-spectrum triazole antifungal that inhibits fungal **cytochrome P450 enzymes**, impairing ergosterol synthesis. - Preferred over SSKI due to better tolerability and predictable dosing. *Terbinafine* - **Terbinafine** is an allylamine antifungal that has been used as an **alternative agent** in sporotrichosis, particularly in cases where itraconazole is contraindicated or not tolerated. - It acts by inhibiting **squalene epoxidase**, disrupting fungal ergosterol biosynthesis. - While primarily used for dermatophyte infections, it has demonstrated activity against Sporothrix species in some studies, though **itraconazole remains preferred**.

Q: A female had a thorn prick 5 years ago. She presents with development of slowly growing $2 \times 2 \mathrm{~cm}$ verrucous lesion which on KOH mount shows the following image. Diagnosis is: (AIIMS Nov 2017)

Chromoblastomycosis. ***Chromoblastomycosis*** - The image shows **sclerotic bodies** (also known as **Medlar bodies**, muriform cells, or fumagoid cells) which are characteristic of *Chromoblastomycosis*. These are thick-walled, septate, dematiaceous (darkly pigmented) fungal cells that reproduce by septation in multiple planes. - The history of a **thorn prick** (trauma allowing inoculation of fungal spores from soil/vegetation), the **slowly growing verrucous lesion**, and the presence of sclerotic bodies on KOH mount are all highly specific for chromoblastomycosis. *Sporotrichosis* - **Sporotrichosis** typically presents with subcutaneous nodules that ulcerate, often forming a **lymphocutaneous spread** along lymphatic vessels. - On microscopy (KOH mount or biopsy), *Sporothrix schenckii* appears as **cigar-shaped budding yeasts** in tissue, which are not seen in the provided image. *Blastomycosis* - **Blastomycosis** is caused by *Blastomyces dermatitidis* and can cause pulmonary, cutaneous, and disseminated infections. Cutaneous lesions can be verrucous but are typically granulomatous with microabscesses. - Microscopic examination (KOH mount) reveals **large, broad-based budding yeast cells**, which are distinct from the sclerotic bodies shown. *Phaeohyphomycosis* - **Phaeohyphomycosis** encompasses a diverse group of infections caused by dematiaceous (pigmented) fungi that, in tissue, grow as **septate hyphae**, yeast-like cells, or a combination of both, but **do not form sclerotic bodies**. - While it can manifest as subcutaneous nodules or cysts, the diagnostic feature in tissue is the presence of pigmented hyphal forms, unlike the characteristic sclerotic bodies in the image.

Q: All of the following statements regarding the image given below are true except:

Inguinal lymphadenopathy. ***Inguinal lymphadenopathy*** - This image illustrates **mycetoma**, a chronic **subcutaneous fungal infection** characterized by localized swelling, draining sinuses, and the extrusion of grains. - Mycetoma typically shows **minimal or no regional lymphadenopathy**, distinguishing it from infections with prominent lymphatic involvement. *Subcutaneous fungal infection* - The image depicts multiple **nodules and sinuses** on the foot, consistent with a **subcutaneous fungal infection** like mycetoma. - These infections are acquired through **traumatic implantation** of fungi into the skin. *Commonly occurs in foot* - Mycetoma, whether **eumycetoma (fungal)** or **actinomycetoma (bacterial)**, most frequently affects the **foot** due to its exposure to soil organisms. - The presentation shown in the image is typical for **mycetoma of the foot**. *Presents with discharging sinus* - A hallmark clinical feature of mycetoma is the formation of **multiple discharging sinuses** that extrude characteristic **grains** (macroscopic colonies of the causative organism). - The image shows **lesions suggestive of sinus tracts** on the foot.

Q: Which of the following statements regarding the condition shown is false?

Usually causes ectothrix infection. ***Usually causes ectothrix infection*** - The image shown depicts **tinea capitis**, specifically **black dot tinea capitis**, which is commonly caused by *T. tonsurans*. - *T. tonsurans* typically causes **endothrix infection**, where fungal spores invade the hair shaft *inside* the follicle, leading to hairs breaking off at the scalp surface, appearing as "black dots." *Can be transmitted from child to child* - **Tinea capitis** is highly contagious and is frequently transmitted among **children** through direct contact with infected individuals or indirectly via contaminated fomites such as combs, hats, and pillowcases. - This mode of transmission makes it a common public health concern in schools and daycares. *Patchy hair loss* - The image clearly shows **patches of hair loss** on the scalp, which is a hallmark symptom of **tinea capitis**. - These patches can be associated with scaling, inflammation, and broken hairs, contributing to the characteristic appearance. *Most commonly caused by T. tonsurans* - In many parts of the world, especially in the United States, **Trichophyton tonsurans** is the predominant cause of **tinea capitis**. - This fungus often results in the **endothrix type** of infection and can lead to the "black dot" appearance observed when hairs break at the surface of the scalp.

Q: What is the most likely diagnosis of the image provided below?

Tinea versicolor. ***Correct: Tinea versicolor*** - The image shows **hypopigmented patches** with subtle scaling, which are characteristic features of tinea versicolor caused by *Malassezia furfur*. - The condition often presents as lighter patches on darker skin or darker patches on lighter skin, and the **fine scale** is often enhanced by scratching. - KOH mount shows **"spaghetti and meatballs" appearance** (short hyphae and round spores). *Incorrect: Tinea corporis* - This condition typically presents as **annular, erythematous lesions** with raised borders and central clearing, often referred to as "ringworm," which is not seen in the image. - Tinea corporis lesions are usually **pruritic** and can occur anywhere on the body, though their appearance is distinct from the diffuse, scaly patches shown. *Incorrect: Pityriasis alba* - Pityriasis alba presents as **ill-defined, hypopigmented macules or patches** often associated with mild scaling, primarily affecting the face, neck, and upper extremities in children and adolescents. - While it causes hypopigmentation, the texture and slight scaling in the image are more indicative of tinea versicolor, especially in an adult. *Incorrect: Vitiligo* - Vitiligo is characterized by **completely depigmented, white macules and patches** with sharply demarcated borders, due to the destruction of melanocytes. - Unlike the patchy, somewhat scaly hypopigmentation seen here, vitiligo lesions typically have a **chalk-white appearance** and lack any scale.

Question 1

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

Accepted Answer

Tinea incognito

Answer

Vagabond disease

Answer

Tinea versicolor

Answer

Tinea capitis

Question 2

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

Accepted Answer

Griseofulvin

Answer

Ketoconazole

Answer

Clotrimazole

Answer

Selenium sulphate

Question 3

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?

Accepted Answer

Trichophyton

Answer

Candidiasis

Answer

Malassezia furfur

Answer

Aspergillosis

Question 4

Vesicular lesions, indistinguishable from primary infection, which arise in other parts of the body of an allergic individual infected with Trichophyton are referred to as?

Accepted Answer

Dermatiphytids

Answer

Trichophytins

Answer

Eschars

Answer

Carbuncles

Question 5

A patient with asymptomatic annular skin lesion as shown presents to OPD. Which investigation should be done?

Accepted Answer

KOH mount

Answer

Biopsy

Answer

Chest X-ray

Answer

HIV testing

Question 6

A carpenter presents with a nodule on dorsum of hand which ulcerates after few days and has not healed for last 2 months. Biopsy of lesion was performed and shown below. All are used in management of this condition except:

Accepted Answer

Cotrimoxazole

Answer

Saturated solution of potassium iodide

Answer

Itraconazole

Answer

Terbinafine

Question 7

A female had a thorn prick 5 years ago. She presents with development of slowly growing $2 	imes 2 \mathrm{~cm}$ verrucous lesion which on KOH mount shows the following image. Diagnosis is: (AIIMS Nov 2017)

Accepted Answer

Chromoblastomycosis

Answer

Sporotrichosis

Answer

Blastomycosis

Answer

Phaeohyphomycosis

Question 8

All of the following statements regarding the image given below are true except:

Accepted Answer

Inguinal lymphadenopathy

Answer

Subcutaneous fungal infection

Answer

Commonly occurs in foot

Answer

Presents with discharging sinus

Question 9

Which of the following statements regarding the condition shown is false?

Accepted Answer

Usually causes ectothrix infection

Answer

Can be transmitted from child to child

Answer

Patchy hair loss

Answer

Most commonly caused by T. tonsurans

Question 10

What is the most likely diagnosis of the image provided below?

Accepted Answer

Tinea versicolor

Answer

Tinea corporis

Answer

Pityriasis alba

Answer

Vitiligo

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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