Dermatological Procedures — MCQs
PUVA therapy is used in all except:
How does narrowband UVB therapy work in psoriasis?
Best method of treatment for segmental trichiasis
Which of the following tests is used in the diagnosis of tinea faciei?
A 70 year old farmer, presented to you with complaints of yellowish discolouration of his finger nails for the past 6 months, he also gives history of recurrent episodes of itching in the groin for which he used to take local home made herbal remedy. On examination 3 of his toe nails also show similar change with tunneling. Which among the following is the best test for rapid confirmation of your diagnosis?
Dyskeratosis refers to which of the following?
Comment on the image shown:
Which of the following is the MOST characteristic feature of skin tags (acrochordons)?
A 40 year old man presented with a flat 1x1cm scaly, itchy black mole on the front of thigh. Examination did not reveal any inguinal lymphodenopathy. The best course of management would be:
Match the following scale types with their lesions. | Scales | Lesions | | :-- | :-- | | 1. Collarette scales | a. Pityriasis versicolour | | 2. Silvery scales | b. Pityriasis rosea | | 3. Mica-like scales | c. Psoriasis | | 4. Branny scales | d. Pityriasis lichenoides |
Dermatological Procedures Indian Medical PG Practice Questions and MCQs
Question 1: PUVA therapy is used in all except:
- A. Psoriasis
- B. Vitiligo
- C. Mycosis fungoides
- D. Melasma (Correct Answer)
Explanation: ***Melasma*** - **PUVA (Psoralen plus UVA) therapy** is contraindicated in melasma due to its potential to worsen hyperpigmentation and cause paradoxical darkening. - Melasma is best managed with topical agents like **hydroquinone**, **tretinoin**, and chemical peels, along with strict **sun protection**. *Psoriasis* - **PUVA therapy** is a well-established and effective treatment for moderate to severe psoriasis, especially for patients with widespread plaques. - It works by inhibiting DNA synthesis and cell proliferation in rapidly dividing keratinocytes, leading to a reduction in psoriatic lesions. *Vitiligo* - **PUVA therapy** is a common treatment for vitiligo, stimulating melanocyte activity and promoting repigmentation in affected areas. - Psoralen sensitizes melanocytes to UVA light, which then encourages melanin production. *Mycosis fungoides* - In its early stages, **mycosis fungoides**, a cutaneous T-cell lymphoma, can be effectively treated with **PUVA therapy**. - PUVA induces apoptosis of malignant T-cells in the skin, leading to remission of skin lesions.
Question 2: How does narrowband UVB therapy work in psoriasis?
- A. Melanin synthesis
- B. Collagen breakdown
- C. Keratinocyte proliferation
- D. T cell apoptosis (Correct Answer)
Explanation: ***T cell apoptosis*** - Narrowband UVB (NB-UVB) therapy primarily works by inducing **apoptosis (programmed cell death)** of activated **T-lymphocytes** in the psoriatic skin lesions. - By reducing the number of these inflammatory cells, NB-UVB helps to suppress the immune response that drives the **excessive keratinocyte proliferation** in psoriasis. *Melanin synthesis* - While UV radiation does stimulate **melanin synthesis**, leading to tanning, this is a secondary effect and not the primary therapeutic mechanism for psoriasis. - Increased melanin helps protect the skin from UV damage but does not directly treat the underlying pathology of psoriasis. *Collagen breakdown* - UV radiation, especially UVA, can contribute to **collagen breakdown** and photodamage over time, but this is an adverse effect, not a therapeutic mechanism for psoriasis. - Psoriasis treatment aims to normalize skin cell growth and reduce inflammation, not degrade collagen. *Keratinocyte proliferation* - Psoriasis is characterized by **accelerated keratinocyte proliferation**; NB-UVB therapy aims to *reduce* this proliferation, not promote it. - The mechanism by which NB-UVB achieves this reduction is primarily through its effects on immune cells, not by directly enhancing keratinocyte growth.
Question 3: Best method of treatment for segmental trichiasis
- A. Argon laser destruction
- B. Cryoepilation (Correct Answer)
- C. Electrolysis
- D. Epilation
Explanation: ***Cryoepilation*** - Cryoepilation is effective for **segmental trichiasis** because it destroys the **hair follicle** and the associated melanocytes, preventing regrowth. - It utilizes **freezing temperatures** to create a zone of necrosis, leading to permanent destruction of misdirected eyelashes. *Argon laser destruction* - Argon laser destruction is generally **less effective** for trichiasis because it primarily targets pigmented structures and may not reliably destroy the entire **hair follicle**. - It has a higher risk of **collateral damage** to surrounding tissues compared to cryotherapy, especially in non-pigmented lashes. *Electrolysis* - Electrolysis is useful for **solitary** or a few misplaced lashes but is **time-consuming** and less practical for segmental involvement. - The procedure involves inserting a **fine needle** into each follicle to deliver an electric current, which can be tedious and prone to recurrence if the follicle isn't fully destroyed. *Epilation* - Epilation, or **plucking**, offers only **temporary relief** as the lash will regrow in 3-6 weeks. - Repeated epilation can lead to **follicular distortion** and ultimately worsen trichiasis or cause secondary complications like infection.
Question 4: Which of the following tests is used in the diagnosis of tinea faciei?
- A. Gram's stain
- B. KOH mount (Correct Answer)
- C. Tissue smear
- D. Wood's lamp
Explanation: ***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.
Question 5: A 70 year old farmer, presented to you with complaints of yellowish discolouration of his finger nails for the past 6 months, he also gives history of recurrent episodes of itching in the groin for which he used to take local home made herbal remedy. On examination 3 of his toe nails also show similar change with tunneling. Which among the following is the best test for rapid confirmation of your diagnosis?
- A. Tzanck smear
- B. KOH mount (Correct Answer)
- C. Woods lamp
- D. Biopsy
Explanation: ***KOH mount*** - A **KOH mount** (potassium hydroxide) dissolves keratinocytes, allowing for direct visualization of fungal elements such as **hyphae** and **spores** under a microscope. This is the **most rapid and cost-effective test** for confirming fungal infections like **onychomycosis**. - The patient's presentation with **yellowish discoloration** and **"tunneling"** of nails (suggesting onycholysis and subungual hyperkeratosis), along with a history of recurrent groin itching (potentially **tinea cruris**), strongly points to a fungal infection. *Tzanck smear* - A **Tzanck smear** is primarily used to detect multinucleated giant cells in **herpesvirus infections** (e.g., herpes simplex, varicella-zoster). - It is not useful for identifying fungal elements responsible for nail discoloration or suspected onychomycosis. *Woods lamp* - A **Woods lamp** uses ultraviolet light to detect specific fluorescent substances, particularly useful for diagnosing certain **bacterial infections** (e.g., *Corynebacterium minutissimum* in erythrasma) or some **tinea capitis** species (*Microsporum*). - Most common dermatophytes causing onychomycosis **do not fluoresce** under a Wood's lamp, making it an unreliable diagnostic tool in this scenario. *Biopsy* - A **nail biopsy** (with histology and special stains like PAS) is a highly accurate diagnostic method for onychomycosis, especially when other tests are inconclusive. - However, it is an **invasive procedure**, takes more time for results, and is generally not the **most rapid** initial test compared to a KOH mount.
Question 6: Dyskeratosis refers to which of the following?
- A. Abnormal, premature keratinization within cells below the stratum granulosum. (Correct Answer)
- B. Discontinuity of the skin showing incomplete loss of epidermis.
- C. Keratinization with retained nuclei in the stratum corneum.
- D. Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.
Explanation: ***Abnormal, premature keratinization within cells below the stratum granulosum.*** - **Dyskeratosis** is a histological term for **premature keratinization** of individual keratinocytes. - This typically occurs in cells that are *below* the **stratum granulosum**, often in the stratum spinosum, indicating abnormal differentiation. *Discontinuity of the skin showing incomplete loss of epidermis.* - This description refers to an **erosion** or **ulceration**, depending on the depth of the epidermal loss. - It does not specifically describe abnormal cellular keratinization. *Keratinization with retained nuclei in the stratum corneum.* - This is the definition of **parakeratosis**, which is a normal finding in mucous membranes but an abnormal finding in skin, often associated with disorders like **psoriasis**. - It indicates incomplete maturation of keratinocytes as they reach the stratum corneum. *Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.* - This describes **hyperkeratosis**, which is an increase in the thickness of the **stratum corneum**. - While it can involve abnormal keratin, it refers to increased thickness, not premature individual cell keratinization.
Question 7: Comment on the image shown:
- A. Corn
- B. Callosity (Correct Answer)
- C. Warts
- D. Cutaneous horn
Explanation: ***Callosity*** - The image displays several **thickened, hyperkeratotic patches** on the palm, characteristic of callosities. - Callosities are caused by repeated friction and pressure, leading to **diffuse epidermal thickening** without a central core. *Corn* - A **corn** is a small, well-demarcated lesion with a **central core** that causes localized pain, unlike the diffuse thickening seen here. - They typically occur over bony prominences and are less spread out than the lesions in the image. *Warts* - **Warts** are caused by the **human papillomavirus (HPV)** and present as rough, elevated lesions with characteristic **black puncta** (thrombosed capillaries) upon paring, which are not visible in the image. - They often have a **papillomatous** or verrucous surface, different from the relatively smooth, thickened appearance here. *Cutaneous horn* - A **cutaneous horn** is a conical projection of **hyperkeratotic material** resembling an animal horn, typically developing on sun-exposed areas. - It is usually a solitary lesion and has a different morphology than the multiple, flat, thickened lesions shown.
Question 8: Which of the following is the MOST characteristic feature of skin tags (acrochordons)?
- A. They commonly occur on the neck and axilla.
- B. They have malignant potential.
- C. They are associated with seborrhoeic keratosis.
- D. They are typically pedunculated. (Correct Answer)
Explanation: ***They are typically pedunculated.*** - **Skin tags (acrochordons)** are benign soft tissue tumors characterized by their **pedunculated morphology** - they are attached to the skin by a narrow stalk or pedicle. - This **pedunculated appearance** is the **most characteristic** and **defining feature** that distinguishes them from other benign skin lesions. - They are typically **soft, flesh-colored or hyperpigmented**, and range from 1-5 mm in size. *They commonly occur on the neck and axilla.* - While **skin tags** frequently occur in areas of friction such as the neck, axilla, eyelids, groin, and inframammary folds, this **location is not specific**. - Many other skin conditions also favor these sites, so location alone is not a characteristic diagnostic feature. *They are associated with seborrhoeic keratosis.* - There is **no established clinical association** between skin tags and seborrheic keratoses. - Both are common **benign skin growths** in adults but represent different pathological entities with different clinical appearances. *They have malignant potential.* - This is **incorrect**. Skin tags are **benign fibrous polyps** with **no malignant potential**. - They do not require removal unless symptomatic or for cosmetic reasons.
Question 9: A 40 year old man presented with a flat 1x1cm scaly, itchy black mole on the front of thigh. Examination did not reveal any inguinal lymphodenopathy. The best course of management would be:
- A. FNAC of lesion
- B. Incision biopsy
- C. Wide excision with inguinal lymphadenectomy
- D. Excision biopsy (Correct Answer)
Explanation: ***Excision biopsy*** - A **flat, scaly, itchy, black mole** is highly suspicious for **melanoma**, and an excision biopsy provides the most accurate histopathological diagnosis and depth assessment. - This procedure removes the entire lesion with a narrow margin of normal-appearing skin, allowing for comprehensive evaluation of its nature and determining further management. *FNAC of lesion* - **Fine needle aspiration cytology (FNAC)** is generally used for evaluating palpable masses or lymph nodes, not primary skin lesions like a suspicious mole. - It provides only cellular samples, making it difficult to assess architectural features, depth of invasion, or determine definitive malignancy in skin lesions. *Incision biopsy* - An **incision biopsy** involves removing only a partial sample of the lesion, which can lead to sampling error and an inaccurate diagnosis if the most aggressive part is missed. - For suspected melanoma, an incomplete biopsy can compromise subsequent staging and definitive treatment planning. *Wide excision with inguinal lymphadenectomy* - This is an **overly aggressive initial approach** before a definitive diagnosis of melanoma and its stage has been established. - **Wide excision** is typically performed after an excision biopsy confirms melanoma and determines its depth, while **lymphadenectomy** is indicated for confirmed lymph node involvement.
Question 10: Match the following scale types with their lesions. | Scales | Lesions | | :-- | :-- | | 1. Collarette scales | a. Pityriasis versicolour | | 2. Silvery scales | b. Pityriasis rosea | | 3. Mica-like scales | c. Psoriasis | | 4. Branny scales | d. Pityriasis lichenoides |
- A. 1-d, 2-c, 3-a, 4-b
- B. 1-c, 2-b, 3-d, 4-a
- C. 1-a, 2-b, 3-d, 4-c
- D. 1-b, 2-c, 3-d, 4-a (Correct Answer)
Explanation: ***1-b, 2-c, 3-d, 4-a*** - **Collarette scales** are pathognomonic of **Pityriasis rosea**, appearing as fine, trailing scales around the periphery of oval lesions in a "Christmas tree" distribution. - **Silvery scales** are the classic hallmark of **Psoriasis**, presenting as thick, adherent, silvery-white scales overlying well-demarcated erythematous plaques. - **Mica-like scales** are characteristic of **Pityriasis lichenoides**, appearing as thick, shiny, adherent scales that can be peeled off like mica sheets. - **Branny scales** are typical of **Pityriasis versicolor**, presenting as fine, powdery scales caused by **Malassezia** yeast overgrowth. *1-d, 2-c, 3-a, 4-b* - Incorrectly matches **collarette scales with Pityriasis lichenoides**, which typically presents with mica-like scales, not collarette scales. - Misassociates **mica-like scales with Pityriasis versicolor**, which characteristically has branny (fine, powdery) scales. *1-c, 2-b, 3-d, 4-a* - Wrongly pairs **collarette scales with Psoriasis**, which is known for thick silvery scales, not peripheral collarette scales. - Incorrectly matches **silvery scales with Pityriasis rosea**, which has collarette scales at lesion periphery, not silvery scales. *1-a, 2-b, 3-d, 4-c* - Falsely associates **collarette scales with Pityriasis versicolor**, which has branny scales from yeast infection, not collarette scales. - Mismatches **branny scales with Psoriasis**, which has characteristic thick silvery scales, not fine powdery scales.
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