Fungal Skin Infections — MCQs

A thirty-two-year-old adult male presents with a chronic suppurative lesion on the angle of the jaw. Microscopic examination shows small abscesses immediately beneath the epidermis with moderate growth of epithelial cords. In the abscess, there are oval, unicellular organisms measuring 20 µm in diameter and having a thick, double-refractive cell wall and cytoplasm containing refractive granules and vacuoles. Which of the following is the most likely diagnosis?

Q30Easy

Muriform cells are characteristically seen in which of the following conditions?

Fungal Skin Infections Indian Medical PG Practice Questions and MCQs

Question 21: A 22-year-old male patient presents with complaints of severe itching and white scaly lesions in the groin for the past month. Which of the following is most likely to be the causative agent?

A. Trichophyton rubrum (Correct Answer)
B. Candida albicans
C. Candida glabrata
D. Malassezia furfur

Explanation: ### Explanation The clinical presentation of severe itching and white scaly lesions in the groin is characteristic of **Tinea cruris** (jock itch), a dermatophytosis. **1. Why Trichophyton rubrum is correct:** *Trichophyton rubrum* is the most common causative agent of dermatophytosis worldwide, including Tinea cruris, Tinea corporis, and Tinea pedis. In Tinea cruris, the lesions typically present as erythematous, scaly plaques with a well-demarcated, active border and central clearing. While the question mentions "white scaly lesions," this refers to the characteristic fine silvery-white scaling seen in chronic dermatophyte infections. **2. Why the other options are incorrect:** * **Candida albicans:** While it causes intertrigo in the groin, it typically presents as bright red, "beefy" erythematous patches with **satellite pustules**. It lacks the central clearing and fine scaling seen in Tinea. * **Candida glabrata:** This is a non-albicans Candida species primarily associated with vulvovaginitis or systemic infections in immunocompromised hosts, rather than primary cutaneous groin infections in healthy males. * **Malassezia furfur:** This is the causative agent of **Pityriasis versicolor**. While it causes scaly hypopigmented or hyperpigmented macules, it predominantly affects the chest, back, and upper arms, and is rarely the primary cause of pruritic groin lesions. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common dermatophyte overall:** *Trichophyton rubrum*. * **Tinea Cruris:** Often associated with concurrent *Tinea pedis* (autoinoculation from feet to groin). * **Diagnosis:** KOH mount shows **septate branching hyphae**. * **Culture:** Sabouraud Dextrose Agar (SDA) is the standard medium. * **Treatment:** Topical azoles (Clotrimazole) or Terbinafine are first-line. Avoid topical steroids as they lead to *Tinea incognito*.

Question 22: Discharging sinus is seen in which of the following conditions?

A. Sporotrichosis
B. Cryptococcosis
C. Histoplasmosis
D. Mycetoma (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Mycetoma** **Why Mycetoma is the correct answer:** Mycetoma is a chronic, granulomatous, subcutaneous infection caused by either fungi (**Eumycetoma**) or bacteria (**Actinomycetoma**). It is clinically characterized by a classic **triad**: 1. **Painless subcutaneous swelling** (usually on the foot, known as "Madura foot"). 2. **Multiple interconnecting discharging sinuses**. 3. **Presence of grains** (sulfur granules) in the discharge, which represent colonies of the causative organism. The infection spreads along fascial planes, eventually involving deeper tissues and bones, leading to the characteristic discharging tracts. **Why other options are incorrect:** * **A. Sporotrichosis:** Known as "Rose gardener’s disease," it typically presents as a **lymphocutaneous** spread. It manifests as a primary nodule/ulcer at the site of inoculation followed by a linear chain of nodules along the draining lymphatics. Discharging sinuses are not a hallmark feature. * **B. & C. Cryptococcosis and Histoplasmosis:** These are primarily systemic/pulmonary fungal infections. While they can have cutaneous manifestations (like molluscum-like papules in Cryptococcosis or oropharyngeal ulcers in Histoplasmosis), they do not typically present with chronic discharging sinuses. **NEET-PG High-Yield Pearls:** * **Dot-in-a-Circle Sign:** A pathognomonic MRI finding for Mycetoma (represents the grain inside the granuloma). * **Actinomycetoma vs. Eumycetoma:** Actinomycetoma (bacterial) progresses faster and is more invasive than Eumycetoma (fungal). * **Commonest cause in India:** *Actinomadura madurae* (Actinomycetoma) and *Madurella mycetomatis* (Eumycetoma). * **Grains:** Black grains are usually seen in Eumycetoma; Yellow/White grains can be seen in both, but are more common in Actinomycetoma.

Question 23: A 16-year-old patient was recently diagnosed with HIV. Which of the following fungal nail infections could be associated?

A. Distal onychomycosis
B. Proximal subungual onychomycosis (Correct Answer)
C. White superficial onychomycosis
D. Paronychia with Candida onychomycosis

Explanation: **Explanation:** **Proximal Subungual Onychomycosis (PSO)** is the rarest form of onychomycosis in the general population but is considered a **pathognomonic clinical marker for HIV/AIDS** or other severe immunocompromised states. In PSO, the fungus (most commonly *Trichophyton rubrum*) invades the nail fold and moves distally under the proximal nail plate. This results in a characteristic white-to-beige discoloration starting at the lunula (the "half-moon" area). In immunocompetent individuals, the nail's protective cuticle and rapid growth usually prevent this route of infection; however, in HIV patients, the loss of T-cell-mediated immunity allows the fungus to bypass these barriers. **Analysis of Incorrect Options:** * **A. Distal Subungual Onychomycosis:** This is the **most common** type of fungal nail infection in the general population. While it can occur in HIV patients, it is not specifically "associated" with or highly suggestive of an underlying immunodeficiency. * **C. White Superficial Onychomycosis:** This involves direct invasion of the dorsal surface of the nail plate, appearing as "chalky white" patches. It is common in the general population and not a specific marker for HIV. * **D. Paronychia with Candida:** This is typically seen in individuals with frequent water exposure (e.g., cooks, laundry workers) or chronic mucocutaneous candidiasis, but it is not the classic presentation linked to HIV-related dermatophytosis. **High-Yield Clinical Pearls for NEET-PG:** * **PSO + HIV:** If you see PSO in a young patient, the next best step is to order an **HIV screening test**. * **Most common cause of Onychomycosis:** *Trichophyton rubrum*. * **Treatment of Choice:** Oral **Terbinafine** (250 mg/day) for 6 weeks (fingernails) or 12 weeks (toenails). * **Diagnosis:** Confirmed by **KOH mount** of nail clippings or fungal culture.

Question 24: All of the following are caused by dermatophytes EXCEPT:

A. Madura foot (Correct Answer)
B. Tinea pedis
C. Tinea capitis
D. Tinea favosa

Explanation: **Explanation:** The correct answer is **Madura foot** (Mycetoma). **1. Why Madura foot is the correct answer:** Dermatophytes are a group of fungi (genera: *Trichophyton, Microsporum, and Epidermophyton*) that require keratin for growth and are restricted to the non-living cornified layers of the skin, hair, and nails. **Madura foot**, or Mycetoma, is a chronic granulomatous inflammatory disease of the subcutaneous tissue. It is caused by either **actinomycetes** (Actinomycetoma - bacteria) or **eumycetes** (Eumycetoma - true fungi like *Madurella mycetomatis*), but notably **not** by dermatophytes. It is characterized by a triad of localized swelling, underlying bone destruction, and the discharge of grains through multiple draining sinuses. **2. Why the other options are incorrect:** * **Tinea pedis:** Also known as "Athlete’s foot," it is a common dermatophyte infection of the feet, most frequently caused by *Trichophyton rubrum*. * **Tinea capitis:** A dermatophyte infection of the scalp hair and skin, common in children, caused by *Trichophyton* and *Microsporum* species. * **Tinea favosa (Favus):** A severe form of tinea capitis characterized by the formation of yellow, cup-shaped crusts called **scutula**. It is caused by *Trichophyton schoenleinii*. **Clinical Pearls for NEET-PG:** * **Dermatophytes** do not invade deeper tissues because they are inhibited by serum and body temperature. * **Wood’s Lamp:** *Microsporum* species (Tinea capitis) show a brilliant green fluorescence. * **Ectothrix vs. Endothrix:** In Tinea capitis, *Endothrix* (spores inside the hair shaft) is seen in *T. tonsurans* (Black dot tinea), while *Ectothrix* (spores outside) is seen in *Microsporum*. * **Mycetoma Triad:** Tumefaction (swelling), Sinuses, and Grains.

Question 25: A farmer presents with subcutaneous swelling and multiple discharging sinuses in the leg. The condition is not responding to antibiotics. What is the likely diagnosis?

A. Madurella (Correct Answer)
B. Nocardia
C. Actinomadura
D. None of the above

Explanation: **Explanation:** The clinical presentation of a farmer (occupational exposure to soil/thorns) with a chronic subcutaneous swelling and multiple discharging sinuses is the classic triad of **Mycetoma** (Madura foot). **1. Why Madurella is correct:** Mycetoma is classified into two types: **Eumycetoma** (fungal) and **Actinomycetoma** (bacterial). The question states the condition is **not responding to antibiotics**, which strongly points toward a fungal etiology (Eumycetoma). **Madurella mycetomatis** is the most common fungal cause of eumycetoma worldwide. It typically presents with "black grains" in the discharge, representing fungal hyphae. **2. Why other options are incorrect:** * **Nocardia & Actinomadura:** These are the causative agents of **Actinomycetoma** (filamentous bacteria). While they present with the same clinical triad, they are generally responsive to antibiotics (like the Welsh regimen: Amikacin + Cotrimoxazole). Since the patient failed antibiotic therapy, these bacterial causes are less likely. **3. NEET-PG High-Yield Pearls:** * **The Triad:** Tumefaction (swelling), Draining sinuses, and Grains (sulfur/black/white). * **Grains:** * **Black grains:** Always fungal (*Madurella*). * **Yellow/White grains:** Can be fungal or bacterial. * **Red grains:** Specifically *Actinomadura pelletieri*. * **Diagnosis:** "Grains" are examined under KOH or crushed for histopathology. * **Radiology:** The **"Dot-in-circle" sign** on MRI is pathognomonic for mycetoma. * **Treatment:** Eumycetoma requires long-term Antifungals (Itraconazole) and often surgical debridement; Actinomycetoma requires the Welsh Regimen.

Question 26: Which of the following is not a fungal infection?

A. Favus
B. Mycosis fungoides (Correct Answer)
C. Kerion
D. Piedra

Explanation: **Explanation:** The correct answer is **B. Mycosis fungoides**. Despite its name, Mycosis fungoides is **not** a fungal infection; it is the most common form of **Cutaneous T-cell Lymphoma (CTCL)**. It is a malignancy of helper T-cells (CD4+) that manifests in the skin through stages: patch, plaque, and tumor. The name is a historical misnomer from the 19th century because the tumor stage resembled mushrooms (fungi). **Analysis of Incorrect Options:** * **Favus (A):** A chronic inflammatory form of *Tinea capitis* usually caused by *Trichophyton schoenleinii*. It is characterized by **scutula** (cup-shaped yellow crusts) and can lead to cicatricial (scarring) alopecia. * **Kerion (C):** An inflammatory, boggy, painful mass on the scalp representing a severe delayed hypersensitivity reaction to a dermatophyte infection (Tinea capitis). It often results in permanent hair loss. * **Piedra (D):** A superficial fungal infection of the hair shaft. **Black Piedra** is caused by *Piedraia hortae*, while **White Piedra** is caused by *Trichosporon* species. **High-Yield Clinical Pearls for NEET-PG:** * **Pautrier’s Microabscesses:** Pathognomonic histological finding in Mycosis fungoides (clusters of atypical T-cells in the epidermis). * **Sezary Syndrome:** The leukemic (systemic) variant of Mycosis fungoides characterized by erythroderma, lymphadenopathy, and atypical circulating T-cells (Sezary cells with cerebriform nuclei). * **Wood’s Lamp in Favus:** Shows a characteristic **dull green** fluorescence.

Question 27: Pityriasis versicolor is caused by which of the following organisms?

A. Candida
B. Rhinosporidium
C. Malassezia (Correct Answer)
D. Tinea

Explanation: **Explanation:** **Pityriasis versicolor** (also known as Tinea versicolor) is a common superficial fungal infection of the stratum corneum. The correct answer is **Malassezia** (specifically *Malassezia furfur*), a lipophilic, dimorphic fungus that is part of the normal skin flora. Under certain conditions (heat, humidity, sweating), it converts from a yeast form to a pathogenic mycelial form, causing the characteristic hypopigmented or hyperpigmented scaly macules. **Analysis of Options:** * **Candida (A):** Causes Candidiasis, typically presenting as erythematous plaques with "satellite lesions" in intertriginous areas (skin folds). * **Rhinosporidium (B):** *Rhinosporidium seeberi* causes Rhinosporidiosis, a chronic granulomatous infection characterized by friable, leafy polyps in the nasal mucosa. * **Tinea (D):** This term refers to dermatophytosis caused by *Trichophyton, Microsporum,* or *Epidermophyton*. Unlike Malassezia, dermatophytes digest keratin and typically present with annular (ring-like) lesions with central clearing. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** KOH mount shows the classic **"Spaghetti and Meatballs"** appearance (short hyphae and clusters of spores). * **Wood’s Lamp:** Lesions show a characteristic **Golden-yellow/Apple-green fluorescence**. * **Clinical Sign:** **Besnier’s Sign** (or "scratch sign")—fine scaling becomes visible when the lesion is scraped with a glass slide or fingernail. * **Culture:** Requires enrichment with lipids (e.g., **Olive oil** overlay) as Malassezia is lipophilic. * **Treatment:** Topical azoles or Selenium sulfide; systemic Ketoconazole/Itraconazole for extensive cases.

Question 28: A patient presents with a non-itchy plaque positive for hyphae. What is the most likely diagnosis?

A. Tinea capitis
B. Tinea corporis
C. Tinea incognito (Correct Answer)
D. Tinea facei

Explanation: ### Explanation The correct answer is **Tinea incognito (Option C)**. **1. Why Tinea incognito is correct:** Tinea incognito refers to a dermatophytic infection that has lost its typical clinical features—specifically the **characteristic itching** and the **well-defined erythematous border**—due to the inappropriate application of topical corticosteroids. Steroids suppress the local inflammatory response, which masks the symptoms (making it "non-itchy") and alters the morphology of the lesion. However, the fungus continues to proliferate in the skin; therefore, a KOH mount will still show abundant **hyphae**, confirming the fungal etiology despite the atypical presentation. **2. Why the other options are incorrect:** * **Tinea corporis (Option B):** This is the classic "ringworm" of the body. It is characteristically **highly pruritic (itchy)** with a prominent, scaly, active border and central clearing. * **Tinea capitis (Option A):** This involves the scalp and hair follicles. While it shows hyphae/spores, it typically presents with alopecia, scaling, or inflammatory kerion, rather than a simple non-itchy plaque on the body. * **Tinea facei (Option D):** This refers to fungal infection of the face. Like tinea corporis, it is usually itchy and erythematous unless it has been modified by steroids (in which case it would also be classified as tinea incognito). **3. High-Yield Clinical Pearls for NEET-PG:** * **The "Steroid Modified" Fungus:** Always suspect Tinea incognito when a "dermatitis-like" lesion fails to respond to steroids or worsens after an initial brief improvement. * **KOH Mount:** In Tinea incognito, the KOH mount often shows an **unusually high density of hyphae** because the steroid-induced local immunosuppression allows for unchecked fungal growth. * **Management:** Immediate cessation of steroids and initiation of systemic antifungal therapy (e.g., Itraconazole or Terbinafine).

Question 29: A thirty-two-year-old adult male presents with a chronic suppurative lesion on the angle of the jaw. Microscopic examination shows small abscesses immediately beneath the epidermis with moderate growth of epithelial cords. In the abscess, there are oval, unicellular organisms measuring 20 µm in diameter and having a thick, double-refractive cell wall and cytoplasm containing refractive granules and vacuoles. Which of the following is the most likely diagnosis?

A. Blastomycosis (Correct Answer)
B. Foreign body reaction
C. Syphilis
D. Tuberculosis

Explanation: **Explanation:** The clinical presentation and histopathology point directly to **Blastomycosis** (specifically North American Blastomycosis caused by *Blastomyces dermatitidis*). **1. Why Blastomycosis is correct:** * **Clinical Presentation:** Chronic suppurative or granulomatous lesions on the face (angle of the jaw) are characteristic of the cutaneous form. * **Histopathology:** The presence of **pseudoepitheliomatous hyperplasia** (described as "moderate growth of epithelial cords") and **intraepidermal/subepidermal microabscesses** are hallmark features. * **Morphology:** The "oval, unicellular organisms (20 µm) with a **thick, double-refractive cell wall**" and refractive granules describe the yeast form of *Blastomyces*. A key diagnostic feature (though not explicitly mentioned here) is the **broad-based budding** yeast. **2. Why other options are incorrect:** * **Foreign body reaction:** Would show multinucleated giant cells and foreign material under polarized light, but not specific unicellular organisms with double-refractive walls. * **Syphilis:** Primary syphilis (chancre) or secondary syphilis (condyloma lata) shows a dense plasma cell infiltrate and endarteritis, not microabscesses with 20 µm yeast cells. * **Tuberculosis (Lupus Vulgaris/Scrofuloderma):** Characterized by caseating granulomas and Acid-Fast Bacilli (AFB). While it can cause jaw lesions (Scrofuloderma), the specific yeast morphology and microabscesses rule it out. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudoepitheliomatous Hyperplasia (PEH):** Often mimics Squamous Cell Carcinoma. It is commonly seen in Blastomycosis, Chromoblastomycosis, Donavanosis, and Lupus Vulgaris. * **Blastomyces Morphology:** Large (8–15 µm, up to 20 µm), broad-based budding, "double-contoured" appearance. * **Systemic Involvement:** Though cutaneous lesions are common, the primary site of infection is usually the **lungs** via inhalation.

Question 30: Muriform cells are characteristically seen in which of the following conditions?

A. Phaeohyphomycosis
B. Chromoblastomycosis (Correct Answer)
C. Rhinosporidiosis
D. Sporotrichosis

Explanation: **Explanation:** **Chromoblastomycosis** is a chronic localized fungal infection of the subcutaneous tissue caused by dematiaceous (pigmented) fungi, most commonly *Fonsecaea pedrosoi*. The hallmark histopathological finding is the presence of **Muriform cells**, also known as **Medlar bodies, Sclerotic bodies, or Copper-penny bodies**. These are thick-walled, dark brown, globe-shaped structures that divide by internal septation (binary fission) rather than budding. Their presence is pathognomonic for this condition. **Analysis of Incorrect Options:** * **Phaeohyphomycosis:** While also caused by pigmented fungi, it is characterized by the presence of pigmented **hyphae and yeast-like forms** in tissue, but it lacks the characteristic muriform cells. * **Rhinosporidiosis:** Caused by *Rhinosporidium seeberi*, it is characterized by large **sporangia** (up to 300 µm) containing thousands of tiny **endospores**, typically presenting as friable nasal polyps. * **Sporotrichosis:** Caused by *Sporothrix schenckii*, it typically shows a granulomatous reaction with the presence of **Asteroid bodies** (central yeast cell surrounded by eosinophilic radiating spicules) or cigar-shaped yeast cells. **NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Often presents as a "cauliflower-like" warty growth, usually on the lower limbs of barefoot workers. * **Pathology:** Look for the "Copper-penny" appearance in a KOH mount or skin biopsy. * **Transepidermal Elimination:** The skin attempts to expel these sclerotic bodies through the epidermis, a process visible on histopathology. * **Treatment:** Itraconazole is the drug of choice; surgical excision or cryotherapy may be used for small lesions.

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

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Antifungal Therapy

Practice Questions

Preventive Strategies

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