Fungal Skin Infections Practice Questions

Q: An eleven-year-old boy has Tinea capitis on his scalp. Which of the following is the most appropriate line of treatment for this condition?

Oral griseofulvin therapy. ***Oral griseofulvin therapy*** - **Systemic antifungal agents** are essential for treating **Tinea capitis**, as the fungal infection is deep within the hair follicles and cannot be reached effectively by topical treatments alone. - **Griseofulvin** is a well-established and effective oral antifungal for **Tinea capitis** in children. *Shaving of the scalp* - While shaving the scalp might reduce some fungal load and facilitate topical treatment, it is **not a definitive treatment** for **Tinea capitis** on its own, as the infection remains deep in the hair follicles. - It does not address the underlying systemic nature of the infection within the hair shaft. *Topical griseofulvin therapy* - **Topical griseofulvin** is generally **ineffective** for **Tinea capitis** because the fungus resides deep within the hair follicle and hair shaft, where topical preparations cannot penetrate sufficiently. - **Systemic absorption** is required to deliver adequate drug concentrations to the site of infection. *Selenium sulphide shampoo* - **Selenium sulfide shampoo** can be used as an **adjunctive therapy** to reduce shedding of spores and prevent spread, but it is **not curative** for **Tinea capitis**. - It helps to reduce skin scaling and fungal burden on the surface but does not eradicate the infection deep within the hair follicles.

Q: What is the correct term for candidiasis of the penis?

Candidal balanitis. ***Balanitis*** - **Candidiasis of the penis** is specifically referred to as Candidal balanitis, an inflammatory condition affecting the **glans penis**. - This term accurately describes the location and cause of the infection. *Oral thrush* - **Oral thrush** is candidiasis of the mouth, characterized by **white patches** on the tongue and oral mucosa. - This term refers to a different anatomical location and is not applicable to penile infection. *No candidiasis present* - This option is incorrect because candidiasis can indeed affect the penis, leading to a recognized clinical condition. - Symptoms like **redness, itching, and discharge** would indicate the presence of candidiasis. *Leukoplakia* - **Leukoplakia** is a condition characterized by **white patches** that develop on the mucous membranes of the mouth, tongue, or sometimes the genitals. - It is a **precancerous lesion** that is not caused by Candida infection, distinguishing it from balanitis.

Q: In adult patients with multiple scaly macules over the chest and back, which single test is the most comprehensive for diagnosing pityriasis versicolor?

10% KOH mount. ***10% KOH mount*** - A **10% KOH mount** is the most comprehensive and definitive single test for diagnosing **pityriasis versicolor** as it directly visualizes the *Malassezia furfur* yeast in its characteristic **spaghetti and meatballs** appearance. - This microscopic examination confirms the presence of pathogenic fungi, distinguishing it from other dermatoses with similar clinical presentations. *Wood Lamp examination* - A Wood lamp examination can show **yellow-gold fluorescence** in affected areas, which is suggestive of *Malassezia furfur*. - However, not all *Malassezia* species or presentations will fluoresce, making it a supportive but not definitive diagnostic tool on its own. *Skin biopsy* - A **skin biopsy** is an invasive procedure and is usually not required for the diagnosis of pityriasis versicolor, which can be readily identified with simpler tests. - While it can confirm fungal elements, it's typically reserved for atypical or refractory cases where other diagnoses are being considered. *All of the options* - While a Wood lamp examination can be helpful and a skin biopsy could confirm the diagnosis, the question asks for the **most comprehensive single test**. - The 10% KOH mount directly identifies the causative organism, making it superior to the other options when only one test can be chosen.

Q: Which sign is indicative of Pityriasis versicolor?

Spaghetti and meatball appearance on KOH examination. ***Spaghetti and meatball appearance on KOH examination*** - This characteristic microscopic finding on a **potassium hydroxide (KOH) preparation** is diagnostic for Pityriasis versicolor, revealing clusters of round yeast cells (meatballs) and short hyphae filaments (spaghetti) of *Malassezia* species. - The examination directly visualizes the fungal elements responsible for the infection, confirming the diagnosis. *Nikolsky sign (associated with pemphigus)* - The Nikolsky sign is positive when the outermost layer of the **epidermis** can be dislodged with lateral pressure, indicating a loss of cell-to-cell adhesion typically seen in **pemphigus vulgaris** and other blistering disorders. - It is not associated with fungal infections like Pityriasis versicolor, which primarily affects the stratum corneum without significant blistering. *Koebner phenomenon (associated with psoriasis)* - The Koebner phenomenon (isomorphic response) refers to the development of new skin lesions at sites of **trauma** in individuals with pre-existing skin conditions like **psoriasis** or lichen planus. - It is a reaction pattern of the skin to injury and does not indicate a fungal infection. *Wickham's striae (associated with lichen planus)* - Wickham's striae are characteristic **fine, lacy white lines** or reticular patterns typically seen on the surface of **papules** and plaques in patients with **lichen planus**. - These are hyperkeratotic manifestations of lichen planus and are not seen in or indicative of Pityriasis versicolor.

Q: Tinea corporis is commonly caused by all the following except which one?

C. albicans. ***C. albicans*** - **_Candida albicans_** is typically associated with **mucocutaneous candidiasis** (e.g., thrush, vaginal yeast infections, intertrigo) and **invasive candidiasis**, not with tinea corporis. - Tinea corporis is caused by **dermatophytes**, which are fungi that specifically infect keratinized tissues, while _C. albicans_ is a yeast that can colonize and infect various body sites. *T. rubrum* - **_Trichophyton rubrum_** is one of the most common causes of **dermatophyte infections** worldwide, including tinea corporis, tinea pedis, and onychomycosis. - It is a **dermatophyte** known for its chronic and often inflammatory presentations in skin infections. *E. floccosum* - **_Epidermophyton floccosum_** is another significant dermatophyte that frequently causes **tinea corporis**, tinea cruris (jock itch), and tinea pedis (athlete's foot). - It is characterized by its ability to exclusively infect skin and nails, not hair. *M. canis* - **_Microsporum canis_** is a common cause of **tinea corporis**, especially in children, and is often acquired from **infected animals** like cats and dogs. - It is a **zoophilic dermatophyte** that typically causes inflammatory lesions on the skin and can also cause tinea capitis.

Q: A washerman presents with thick erosion and discolouration of the web spaces of the toes. What is the most likely diagnosis?

Tinea Pedis. ***Tinea Pedis*** - This patient's occupation as a **washerman** exposes his feet to constant **dampness and maceration**, which creates an ideal environment for **dermatophyte infections** like tinea pedis (athlete's foot). - The symptoms of **thick erosion** and **discoloration** in the **web spaces of the toes** are classic presentations of interdigital tinea pedis. *Psoriasis* - Psoriasis typically presents with **well-demarcated erythematous plaques** covered with silvery scales, which are not described here. - While it can affect the feet, it usually involves the soles and dorsal aspects rather than primarily the interdigital web spaces with erosion. *Candidiasis* - Cutaneous candidiasis often presents with **erythematous patches** with **satellite lesions** and is common in moist areas, but the description of thick erosion and discoloration in the web spaces is more characteristic of tinea pedis. - While *Candida* can cause interdigital infections, the description points more strongly towards dermatophytes. *Tinea Unguium* - Tinea unguium (onychomycosis) is a **fungal infection of the nails**, causing thickening, discoloration, and crumbling of the nail plate. - The symptoms described are focused on the **skin of the web spaces of the toes**, not the nails themselves.

Q: Which of the following tests is used in the diagnosis of tinea faciei?

KOH mount. ***KOH mount*** - A **KOH (potassium hydroxide) mount** is the gold standard for diagnosing **dermatophyte infections**, including **tinea faciei**. - The KOH solution dissolves keratinocytes, allowing for the visualization of fungal **hyphae and spores** under a microscope. *Gram's stain* - **Gram's stain** is primarily used to differentiate bacterial species based on their cell wall properties. - It does not effectively visualize **fungal elements** and is therefore not used for diagnosing tinea infections. *Tissue smear* - A **tissue smear** involves examining cells from a lesion, typically for conditions like viral infections (e.g., Tzanck smear for herpes) or some cutaneous malignancies. - It is not the standard or preferred method for identifying **dermatophyte fungal structures**. *Wood's lamp* - A **Wood's lamp**, which emits ultraviolet light, is used to detect certain fungal infections (e.g., *Microsporum* species causing tinea capitis) and bacterial conditions (e.g., erythrasma). - Many common dermatophytes causing **tinea faciei** (e.g., *Trichophyton*) do not fluoresce under a Wood's lamp, making it an unreliable diagnostic tool for this specific condition.

Q: Which of the following is the causative agent of Favus?

Trichophyton schoenleinii. ***Trichophyton schoenleinii*** - This fungus is the classic causative agent of **Favus**, a severe form of tinea capitis characterized by **sulfur-yellow cup-shaped crusts** called scutula. - Favus often leads to **permanent scarring alopecia** due to follicular destruction. *Microsporum audouinii* - This species is a common cause of **epidemic tinea capitis** in children, particularly in schools. - It typically causes **gray patch tinea capitis**, characterized by scaly patches and broken hairs, but not scutula. *Microsporum canis* - *M. canis* is a **zoophilic fungus**, commonly transmitted to humans from infected cats and dogs. - It is a frequent cause of **inflammatory tinea capitis** and tinea corporis, presenting with scaling, erythema, and occasional pustules. *Trichophyton mentagrophytes* - This dermatophyte can cause various forms of tinea, including **tinea pedis (athlete's foot)**, tinea cruris, and highly inflammatory tinea capitis or barbae. - It is known for causing both **inflammatory and non-inflammatory lesions**, but not specifically Favus.

Question 1

An eleven-year-old boy has Tinea capitis on his scalp. Which of the following is the most appropriate line of treatment for this condition?

Accepted Answer

Oral griseofulvin therapy

Answer

Shaving of the scalp

Answer

Topical griseofulvin therapy

Answer

Selenium sulphide shampoo

Question 2

What is the correct term for candidiasis of the penis?

Accepted Answer

Candidal balanitis

Answer

Oral thrush

Answer

No candidiasis present

Answer

Leukoplakia

Question 3

In adult patients with multiple scaly macules over the chest and back, which single test is the most comprehensive for diagnosing pityriasis versicolor?

Accepted Answer

10% KOH mount

Answer

All of the options

Answer

Skin biopsy

Answer

Wood Lamp examination

Question 4

Which sign is indicative of Pityriasis versicolor?

Accepted Answer

Spaghetti and meatball appearance on KOH examination

Answer

Nikolsky sign (associated with pemphigus)

Answer

Wickham's striae (associated with lichen planus)

Answer

Koebner phenomenon (associated with psoriasis)

Question 5

Tinea corporis is commonly caused by all the following except which one?

Accepted Answer

C. albicans

Answer

M. canis

Answer

T. rubrum

Answer

E. floccosum

Question 6

A washerman presents with thick erosion and discolouration of the web spaces of the toes. What is the most likely diagnosis?

Accepted Answer

Tinea Pedis

Answer

Tinea Unguium

Answer

Candidiasis

Answer

Psoriasis

Question 7

Which of the following tests is used in the diagnosis of tinea faciei?

Accepted Answer

KOH mount

Answer

Gram's stain

Answer

Tissue smear

Answer

Wood's lamp

Question 8

Which of the following is the causative agent of Favus?

Accepted Answer

Trichophyton schoenleinii

Answer

Microsporum audouinii

Answer

Trichophyton mentagrophytes

Answer

Microsporum canis

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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