Fungal Skin Infections Practice Questions

Q: A 25-year-woman developed scaly, pruritic lesions on her back. She applied topical steroids on the lesion, following the advice of a quack. Subsequently her lesions worsened. What is the diagnosis?

Tinea incognito. ***Tinea incognito*** - This condition occurs when a **dermatophyte infection** is masked or altered by the inappropriate application of **topical corticosteroids**, leading to atypical appearance and worsening of the lesion. - The history of applying topical steroids and subsequent worsening of lesions is characteristic of tinea incognito, as steroids suppress the immune response, allowing the fungus to spread more aggressively and alter its typical morphology. *Tinea corporis* - **Tinea corporis** typically presents as a well-demarcated, annular (ring-shaped) lesion with an **active, raised border** and central clearing. - While it is caused by a **dermatophyte infection**, the key differentiating feature here is the worsening after steroid application, which points away from uncomplicated tinea corporis. *Black dot tinea* - **Black dot tinea** is a form of **tinea capitis** (scalp ringworm), characterized by broken hair shafts at the scalp surface, appearing as "black dots." - This diagnosis is incorrect because the lesion is described as being on the patient's **back**, not the scalp, and the morphology does not match. *Dermographism* - **Dermographism** is a type of physical urticaria where firm stroking of the skin causes a linear **itchy wheal** to develop, resembling writing on the skin. - This is a **mechanical urticaria**, an allergic reaction, and does not involve fungal infection or the scaly, pruritic lesions described in the case.

Q: The given picture depicts:

Tinea imbricata. ***Tinea imbricata*** - The image shows a distinctive pattern of **concentric, lamellar scales**, often described as "tiles" or "fish scales," which is a hallmark of **tinea imbricata**. - This presentation is caused by specific fungal species, primarily *Trichophyton concentricum*, and is common in certain tropical and subtropical regions. *Toxic epidermal necrolysis* - This condition is characterized by **widespread epidermal detachment** resembling severe burns, leading to large areas of denuded skin and mucosal involvement. - It does not typically present with the **concentric scaly pattern** seen in the image. *Atopic dermatitis* - Characterized by **eczematous lesions**, typically itchy, dry, inflamed skin, often with lichenification in chronic cases. - The appearance is distinct from the **patterned scaling** observed in the image, instead showing erythema, papules, vesicles, and crusting. *Psoriasis* - Psoriasis typically presents as **well-demarcated erythematous plaques** covered with **silvery scales**, often found on extensor surfaces like elbows and knees. - While it involves scaling, it does not exhibit the specific **concentric, imbricated (overlapping) scale pattern** characteristic of the image.

Q: A 30-year-old washerwoman presents with the following lesion. All are correct except:

Tinea unguium. ***Tinea unguium*** - **Tinea unguium** (onychomycosis) is a **dermatophyte infection** of the nail plate, typically caused by *Trichophyton* species, not *Candida*. - The image shows **chronic paronychia** caused by *Candida* affecting the nail fold, which is a completely different condition from tinea unguium. *Caused by normal commensal of GIT* - *Candida albicans* is indeed a **normal commensal** of the gastrointestinal tract and can cause chronic paronychia in washerwomen. - Constant **water exposure** allows this opportunistic organism to colonize and infect the periungual tissues. *Rule out diabetes mellitus in recurrent episodes* - **Recurrent candidal infections** warrant screening for **diabetes mellitus** due to impaired immune function and elevated glucose levels. - Diabetic patients have increased susceptibility to **opportunistic fungal infections** including chronic paronychia. *Deformed nail plate* - The image clearly shows **nail dystrophy** with irregular, discolored, and thickened nail plate secondary to chronic inflammation. - **Chronic paronychia** affects the nail matrix, leading to **abnormal nail growth** and permanent deformation.

Q: A 20-year-old patient presents with an extremely itchy lesion on one arm. Diagnosis is:

Tinea imbricata. ***Tinea imbricata*** - The **concentric, overlapping scales forming prominent rings** or "imbricated" patterns are **pathognomonic** for *Tinea imbricata*, caused by **Trichophyton concentricum**. - This **rare dermatophytosis** is geographically restricted to **tropical regions of the Pacific, Southeast Asia, and Central/South America** and causes **intensely itchy lesions** with distinctive overlapping scale patterns. *Tinea corporis* - Typically presents as a **single red, annular lesion with raised, scaly border** and central clearing, not the extensive overlapping concentric rings seen in this case. - While it can be itchy, the **morphology lacks the pathognomonic imbricated scale pattern** characteristic of the correct diagnosis. *Tinea incognito* - Refers to dermatophyte infections **modified by inappropriate topical steroid use**, leading to **suppressed inflammation** and atypical morphology. - The distinctive **classical imbricated pattern** shown excludes this diagnosis, as steroids would obscure such well-defined morphological features. *Tinea manuum* - Specifically affects the **hands**, presenting with **unilateral scaling, erythema, and hyperkeratosis** on palms and fingers. - The **arm location** and **concentric ring morphology** are inconsistent with typical hand involvement patterns seen in this condition.

Q: The given KOH mount of patient shows:

Spaghetti and meatball appearance. ***Spaghetti and meatball appearance*** - This description refers to the characteristic microscopic appearance of *Malassezia* species on a **KOH mount**, showing short hyphae ("spaghetti") and spherical yeast cells ("meatballs"). - This finding is typical of **tinea versicolor** and sometimes seborrheic dermatitis. *Budding yeasts and pseudohyphae* - This appearance is characteristic of *Candida albicans*, which causes conditions like candidiasis or thrush. - While yeasts are present, the hyphae in the image are short and fragmented, unlike the continuous pseudohyphae of *Candida*. *Clusters of pigmented cells* - This description would be more indicative of conditions like **tinea nigra** or certain bacterial infections. - The image clearly shows fungal elements (yeasts and hyphae), not pigmented cellular clusters. *Septate hyphae* - While the image shows some hyphae, the dominant feature is a mix of short hyphae and round yeast forms, which is specific to *Malassezia*. - **Septate hyphae** alone are a general characteristic of many dermatophytes (e.g., *Tinea corporis*), but not the hallmark of *Malassezia* when combined with spherical yeasts.

Q: A 25-year-old construction worker presents with following skin lesions. All are true about the image shown except: (Recent NEET Pattern 2016-17)

Oral terbinafine is drug of choice. ***Correct Answer: Oral terbinafine is drug of choice*** - **Oral terbinafine is NOT the drug of choice** for tinea versicolor, making this the correct answer to the "EXCEPT" question - **Malassezia species lack the enzyme** (squalene epoxidase) necessary to convert terbinafine into its active form - Terbinafine is primarily used for **dermatophyte infections** (tinea corporis, cruris, pedis), not Malassezia infections - **Drug of choice for tinea versicolor**: Topical azoles (ketoconazole shampoo, selenium sulfide) or oral azoles (fluconazole, itraconazole) for extensive disease *Incorrect: Wood's lamp will produce yellow fluorescence* - This statement is TRUE, so it is not the exception - Wood's lamp examination reveals characteristic **yellow-gold to coppery-orange fluorescence** in tinea versicolor - The fluorescence is due to production of **porphyrins (malassezin)** by the *Malassezia* organism *Incorrect: KOH mount shows spaghetti and meat ball appearance* - This statement is TRUE, so it is not the exception - **KOH mount** of skin scrapings shows short, stubby **hyphae** (spaghetti) and round **spores** (meatballs) - This is the **pathognomonic microscopic finding** for *Malassezia furfur* *Incorrect: Caused by Malassezia furfur* - This statement is TRUE, so it is not the exception - The image shows **hypopigmented and hyperpigmented patches** on the trunk, characteristic of tinea versicolor - Caused by dimorphic yeast ***Malassezia furfur*** (also *M. globosa*, *Pityrosporum ovale*) - Normal skin commensal that becomes pathogenic in hot, humid conditions

Q: All are true about the infection shown in the image EXCEPT:

Absence of any inflammatory response or pain. ***Absence of any inflammatory response or pain*** - Fungal infections like candidiasis typically elicit an **inflammatory response**, leading to symptoms such as **erythema, pruritus, and pain or discomfort**, especially in intertriginous areas. - The image shows clear signs of inflammation, including **redness and maceration**, which would be associated with discomfort. *Satellite pustules* - Cutaneous candidiasis, particularly in intertriginous areas, is often characterized by a main erythematous patch with surrounding smaller lesions known as **satellite pustules or papules**. - These satellite lesions are a classic diagnostic feature, indicating the spread of the fungal infection beyond the main lesion. *Caused by normal saprophytic inhabitants of the gut* - *Candida albicans*, the primary cause of cutaneous candidiasis, is a **normal commensal organism** found in the gastrointestinal tract and on mucous membranes. - Under conditions such as warmth, moisture, immunosuppression, or antibiotic use, *Candida* can overgrow and become pathogenic. *Involves intertriginous areas* - The image clearly depicts an infection in an **intertriginous area**, specifically between the fingers (likely the web space). - These areas are prone to candidiasis due to their **warm, moist environment**, which favors fungal growth.

Q: The image shows a KOH mount suggestive of diagnosis of:

Pityriasis versicolor. ***Pityriasis versicolor*** - The KOH mount shows **short hyphae** and **clusters of spores** (yeast cells), which is characteristic of the "spaghetti and meatballs" appearance associated with *Malassezia furfur*, the causative agent of pityriasis versicolor. - This specific microscopic finding is a hallmark for diagnosing *Pityriasis Versicolor*, differentiating it from typical dermatophyte infections. *Tinea imbricata* - This condition is caused by *Trichophyton concentricum* and on KOH mount would typically show **long, branched hyphae**, without the characteristic yeast clusters seen in the image. - While it is a superficial fungal infection, the morphology of the causative organism under microscopy is distinct from what is presented. *Pompholyx* - Pompholyx (dyshidrotic eczema) is an **eczematous condition** characterized by small, itchy blisters on the hands and feet and is **not a fungal infection**. - A KOH mount would typically show **no fungal elements** in a patient with pompholyx, hence it is an unlikely diagnosis given the image. *Tinea capitis* - Tinea capitis, a fungal infection of the scalp and hair shafts, is caused by dermatophytes and would show **hyphae and spores within or surrounding hair shafts** on a KOH mount. - The image does not show hair shafts or the typical morphology of dermatophyte hyphae associated with tinea capitis.

Q: The image shows a KOH mount suggestive of diagnosis of:

Pityriasis versicolor. ***Pityriasis versicolor*** - The image clearly shows a KOH mount with **short, curved hyphae** and **clusters of round yeast cells**, characteristic of **spaghetti and meatballs** appearance, which is pathognomonic for *Malassezia furfur*, the causative agent of pityriasis versicolor. - This common superficial fungal infection presents as hypo- or hyperpigmented patches, primarily on the trunk, neck, and arms, and is diagnosed by this distinctive microscopic finding. *Tinea imbricata* - This is a rare form of tinea corporis caused by *Trichophyton concentricum*, characterized by **concentric, scaly rings**. - A KOH mount would show **long, branching hyphae** without the characteristic yeast clusters seen in the image. *Pompholyx* - **Pompholyx** (dyshidrotic eczema) is an endogenous eczematous condition characterized by **deep-seated vesicles** and bullae on the palms, soles, and sides of the fingers. - It is a non-infectious condition, and a KOH mount would show **no fungal elements**; instead, it would reveal inflammatory cells if any scraping were done. *Tinea capitis* - **Tinea capitis** is a dermatophyte infection of the scalp and hair, primarily affecting children. - A KOH mount from hair or scalp scrapings would show **arthrospores** (either endothrix or ectothrix) and **hyphae within or around the hair shaft**, not the yeast and short hyphae clusters characteristic of *Malassezia*.

Q: Which of the following is not effective against this condition?

Griseofulvin. ***Griseofulvin*** - The image shows **Pityriasis Versicolor**, characterized by hyperpigmented or hypopigmented patches with fine scaling, caused by *Malassezia furfur*. - Griseofulvin is an oral antifungal primarily used for **dermatophyte infections** (tinea infections) of the skin, hair, and nails, and is not effective against *Malassezia furfur*. *Topical Ketoconazole* - **Ketoconazole** is a broad-spectrum azole antifungal that is highly effective against a wide range of fungi, including *Malassezia furfur*. - It works by inhibiting the synthesis of **ergosterol**, a crucial component of fungal cell membranes, leading to cell death. *Topical selenium sulphide* - **Selenium sulfide** is an effective antifungal agent commonly used in shampoos and lotions to treat conditions like dandruff and **Pityriasis Versicolor**. - It works by reducing the growth of *Malassezia furfur* and has **keratolytic** properties, helping to shed the affected skin cells. *Topical sulfur preparations* - **Sulfur** has antifungal, antibacterial, and keratolytic properties, making it useful in treating various skin conditions. - Topical sulfur preparations are effective in treating **Pityriasis Versicolor** by inhibiting fungal growth and promoting exfoliation of the affected epidermis.

Question 1

A 25-year-woman developed scaly, pruritic lesions on her back. She applied topical steroids on the lesion, following the advice of a quack. Subsequently her lesions worsened. What is the diagnosis?

Accepted Answer

Tinea incognito

Answer

Tinea corporis

Answer

Black dot tinea

Answer

Dermographism

Question 2

The given picture depicts:

Accepted Answer

Tinea imbricata

Answer

Toxic epidermal necrolysis

Answer

Atopic dermatitis

Answer

Psoriasis

Question 3

A 30-year-old washerwoman presents with the following lesion. All are correct except:

Accepted Answer

Tinea unguium

Answer

Rule out diabetes mellitus in recurrent episodes

Answer

Deformed nail plate

Answer

Caused by normal commensal of GIT

Question 4

A 20-year-old patient presents with an extremely itchy lesion on one arm. Diagnosis is:

Accepted Answer

Tinea imbricata

Answer

Tinea corporis

Answer

Tinea incognito

Answer

Tinea manuum

Question 5

The given KOH mount of patient shows:

Accepted Answer

Spaghetti and meatball appearance

Answer

Budding yeasts and pseudohyphae

Answer

Clusters of pigmented cells

Answer

Septate hyphae

Question 6

A 25-year-old construction worker presents with following skin lesions. All are true about the image shown except: (Recent NEET Pattern 2016-17)

Accepted Answer

Oral terbinafine is drug of choice

Answer

Wood's lamp will produce yellow fluorescence

Answer

KOH mount shows spaghetti and meat ball appearance

Answer

Caused by Malassezia furfur

Question 7

All are true about the infection shown in the image EXCEPT:

Accepted Answer

Absence of any inflammatory response or pain

Answer

Satellite pustules

Answer

Caused by normal saprophytic inhabitants of the gut

Answer

Involves intertriginous areas

Question 8

The image shows a KOH mount suggestive of diagnosis of:

Accepted Answer

Pityriasis versicolor

Answer

Tinea imbricata

Answer

Pompholyx

Answer

Tinea capitis

Question 9

The image shows a KOH mount suggestive of diagnosis of:

Accepted Answer

Pityriasis versicolor

Answer

Tinea imbricata

Answer

Pompholyx

Answer

Tinea capitis

Question 10

Which of the following is not effective against this condition?

Accepted Answer

Griseofulvin

Answer

Topical Ketoconazole

Answer

Topical selenium sulphide

Answer

Topical sulfur preparations

Fungal Skin Infections — MCQs

Fungal Skin Infections — MCQs

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