Curettage and Electrodessication — MCQs
Sun damage causes malignant transformation of the skin by:
Dilatation & curettage (D&C) is contraindicated in-
For the treatment of basal cell carcinoma, what is the popular surgery that is carried out?
Which of the following is the MOST characteristic feature of skin tags (acrochordons)?
In which of the following conditions is the Koebner phenomenon most commonly observed?
Unna boot is used for the treatment of which condition?
Which of the following is NOT true regarding patch testing?
A 45-year-old farmer presents with a 3-year history of itchy, erythematous papular lesions on the face, neck, 'V' area of the chest, and the dorsum of the hands and forearms. The lesions are more severe in the summer and improve significantly in the winter. What is the most appropriate diagnostic test for this condition?
Patch test is done to document which type of hypersensitivity?
A 19-year-old man develops a rash in the groin area. On examination, it is a large well-demarcated area of tan-brown discoloration around his left inguinal area. There is some scaling of the lesion when brushed with a tongue depressor. Which of the following is the most appropriate initial diagnostic test?
Curettage and Electrodessication Indian Medical PG Practice Questions and MCQs
Question 1: Sun damage causes malignant transformation of the skin by:
- A. Direct DNA damage
- B. Free radical formation
- C. Induction of pyrimidine dimers (Correct Answer)
- D. Mutation of p53 due to UV exposure
Explanation: ***Induction of pyrimidine dimers*** - **Ultraviolet (UV) radiation** from the sun causes the formation of **covalent bonds between adjacent pyrimidine bases** (thymine or cytosine) on the same DNA strand, creating pyrimidine dimers [1]. - These dimers lead to **DNA distortion**, interfering with DNA replication and transcription, and if not repaired, can result in **mutations** that contribute to carcinogenesis [2]. *Free radical formation* - While UV radiation can induce **reactive oxygen species** (free radicals) that cause DNA damage, the primary mechanism of malignant transformation leading to skin cancer is the direct formation of pyrimidine dimers. - Free radicals cause a variety of oxidative damage to DNA, proteins, and lipids, but **pyrimidine dimers are unique to UV exposure** and are the main initiators of UV-induced skin cancer. *Direct DNA damage* - This option is too broad; while pyrimidine dimer formation is a form of direct DNA damage, it is the **most specific and significant mechanism** of malignant transformation due to sun exposure [3]. - Non-specific direct DNA damage can also occur from other sources, but the hallmark of UV-induced damage is the creation of **photoproducts like pyrimidine dimers**. *Mutation of p53 due to UV exposure* - **p53 gene mutations** are frequently found in skin cancers, particularly **squamous cell carcinoma**, and are indeed induced by UV radiation. - However, the mutation of p53 is a **consequence** of the initial DNA damage (specifically pyrimidine dimers not being repaired), not the primary mechanism by which sun damage *causes* malignant transformation [2]. The induction of pyrimidine dimers *leads* to these mutations. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 322-323. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 332-333. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 220-221.
Question 2: Dilatation & curettage (D&C) is contraindicated in-
- A. Pelvic inflammatory disease (PID) (Correct Answer)
- B. Endometriosis
- C. Ectopic pregnancy
- D. Abnormal uterine bleeding
Explanation: ***Pelvic inflammatory disease (PID)*** - D&C is **contraindicated** in PID due to the high risk of **spreading pre-existing infection** from the cervix or vagina into the sterile uterine cavity and beyond. - This procedure can worsen the infection, potentially leading to **sepsis**, **tubo-ovarian abscesses**, or chronic pain. *Endometriosis* - D&C is not typically contraindicated in **endometriosis**, as it is sometimes used diagnostically to rule out other causes of abnormal uterine bleeding, though it isn't a treatment for endometriosis itself. - Endometriosis involves the presence of **endometrial tissue outside the uterus**, and a D&C performed on the uterus does not directly exacerbate this condition. *Ectopic pregnancy* - D&C is not contraindicated in **ectopic pregnancy**; however, it is not the primary treatment. - A D&C may be performed if the diagnosis of ectopic pregnancy is uncertain and to rule out an **intrauterine pregnancy** or retained products of conception. *Abnormal uterine bleeding* - D&C is frequently indicated and can be both **diagnostic and therapeutic** for abnormal uterine bleeding, especially to investigate causes like polyps, fibroids, or endometrial hyperplasia. - It helps in obtaining tissue for **histopathological examination** to guide further management.
Question 3: For the treatment of basal cell carcinoma, what is the popular surgery that is carried out?
- A. Mohs surgery (Correct Answer)
- B. Superficial laser surgery
- C. Curettage and electrodesiccation
- D. Wide local excision
Explanation: ***Mohs surgery*** - **Mohs micrographic surgery** is the most popular and highly effective procedure specifically designed for **basal cell carcinoma (BCC)**, especially on the face and other cosmetically sensitive areas. - It involves the **progressive removal** of thin layers of skin, which are immediately examined under a microscope, allowing for complete tumor removal while preserving maximum healthy tissue. - Mohs surgery has the **highest cure rate** (95-99%) for BCC and is particularly preferred for high-risk locations, recurrent tumors, and poorly defined borders. *Superficial laser surgery* - While lasers can sometimes be used for very superficial skin lesions, **superficial laser surgery** is generally not the primary treatment for established **BCC** due to the risk of incomplete removal and recurrence. - It lacks the **histological margin control** provided by Mohs surgery, which is crucial for ensuring complete eradication of BCC. *Curettage and electrodesiccation* - **Curettage and electrodesiccation** is an alternative surgical treatment for small, low-risk BCCs in non-critical areas. - However, it has **lower cure rates** (85-95%) compared to Mohs surgery and does not provide histological margin assessment. - It is less preferred for facial BCCs where cosmetic outcome and complete removal are critical. *Wide local excision* - **Wide local excision** is a standard surgical approach that removes the tumor with predetermined margins (typically 4-5 mm for BCC). - While effective, it requires **larger tissue removal** compared to Mohs surgery and lacks the real-time microscopic margin control. - Mohs surgery remains more popular due to its tissue-sparing nature and higher cure rates, especially in cosmetically sensitive areas.
Question 4: 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 5: In which of the following conditions is the Koebner phenomenon most commonly observed?
- A. Psoriasis (Correct Answer)
- B. Lichen planus
- C. All of the options
- D. Viral warts
Explanation: ***Correct: Psoriasis*** - **Psoriasis** is the **most classic and commonly cited example** of the Koebner phenomenon (isomorphic response) - New psoriatic plaques characteristically develop at sites of cutaneous trauma, scratches, or surgical incisions in 25-50% of psoriasis patients - This is a **pathognomonic feature** frequently tested in competitive exams and considered the prototype condition for demonstrating this phenomenon - The mechanism involves inflammatory cascades triggered by trauma in genetically predisposed skin *Incorrect: Lichen planus* - While lichen planus does exhibit the Koebner phenomenon with purplish polygonal papules appearing along scratch lines, it is **less commonly observed** compared to psoriasis - Seen in approximately 10-25% of lichen planus cases - Not considered the primary example when teaching about Koebner phenomenon *Incorrect: Viral warts* - Viral warts can demonstrate **pseudo-Koebner phenomenon** where new warts form along trauma lines due to viral inoculation - This is more accurately described as **autoinoculation** rather than true isomorphic response - Less commonly discussed in the context of classic Koebner phenomenon compared to psoriasis *Incorrect: All of the options* - While all three conditions can show Koebner-like responses, the question asks for "**most commonly observed**" - Psoriasis remains the **gold standard** and most frequently encountered example in clinical practice and medical literature
Question 6: Unna boot is used for the treatment of which condition?
- A. Diabetic foot ulcer
- B. Varicose ulcers (Correct Answer)
- C. Ankle instability
- D. Calcaneum fracture
Explanation: **Explanation:** The **Unna boot** is a specialized compression dressing used primarily for the management of **venous stasis ulcers (varicose ulcers)**. It consists of a zinc oxide-impregnated bandage, often containing calamine and glycerin, which is wrapped around the lower leg from the base of the toes to just below the knee. **Why it is the correct answer:** The mechanism of action is based on **compression therapy**. As the bandage dries, it becomes semi-rigid. When the patient walks, the calf muscles contract against this rigid barrier, significantly enhancing the **musculovenous pump** efficiency. This reduces venous hypertension, decreases edema, and promotes the healing of chronic venous ulcers. **Analysis of Incorrect Options:** * **Diabetic foot ulcer:** These are primarily neuropathic or ischemic. Treatment focuses on offloading pressure (e.g., total contact casts) and revascularization, rather than the semi-rigid compression provided by an Unna boot. * **Ankle instability:** This requires mechanical stabilization via braces, taping, or surgical intervention to protect ligaments, not a medicated compression wrap. * **Calcaneum fracture:** Fractures require rigid immobilization (plaster casts) or surgical fixation. An Unna boot does not provide sufficient structural support for bone healing. **High-Yield Clinical Pearls for NEET-PG:** * **Composition:** Zinc oxide (promotes healing), Calamine (soothes skin), and Glycerin. * **Contraindication:** It should **not** be used in patients with severe Peripheral Arterial Disease (ABI < 0.5) as compression can worsen ischemia. * **Application:** It is typically changed once a week. * **Gold Standard:** While Unna boots are classic, multilayer compression wraps are now often considered the gold standard for venous ulcers.
Question 7: Which of the following is NOT true regarding patch testing?
- A. Used to diagnose allergic contact dermatitis
- B. Readings are typically taken after 48 hours
- C. False negative results can occur in patients with angry back syndrome (Correct Answer)
- D. The T.R.U.E. test is a type of patch test
Explanation: **Explanation:** **1. Why Option C is the correct answer (The False Statement):** **Angry Back Syndrome** (also known as **Excited Skin Syndrome**) refers to a state of skin hyper-reactivity where a strong positive reaction at one patch test site triggers non-specific positive reactions at other sites. Therefore, it leads to **false-positive** results, not false-negative results. This occurs because the skin's threshold for irritation is lowered globally due to a localized severe inflammatory response. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** Patch testing is the **gold standard** for diagnosing Type IV (delayed-type) hypersensitivity reactions, specifically **Allergic Contact Dermatitis (ACD)**. * **Option B:** In a standard protocol, patches are applied for **48 hours**, removed, and the first reading is taken. a second reading is typically taken at **72–96 hours** to identify delayed reactions. * **Option D:** The **T.R.U.E. test** (Thin-layer Rapid Use Epicutaneous test) is a widely used, standardized, ready-to-use patch testing system containing common allergens impregnated into polyester patches. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Type IV Hypersensitivity (Cell-mediated). * **Prick Test vs. Patch Test:** Prick tests are for Type I (IgE-mediated) reactions (e.g., asthma, urticaria), while Patch tests are for Type IV. * **Grading (ICDRG):** * **+:** Weak (non-vesicular) reaction (erythema, infiltration). * **++:** Strong (vesicular) reaction. * **+++:** Extreme (bullous) reaction. * **IR:** Irritant reaction (usually sharply demarcated, "burned" appearance). * **Contraindication:** Testing should not be done during an acute flare-up of dermatitis or if the patient is on high-dose systemic corticosteroids (usually >15-20mg prednisolone).
Question 8: A 45-year-old farmer presents with a 3-year history of itchy, erythematous papular lesions on the face, neck, 'V' area of the chest, and the dorsum of the hands and forearms. The lesions are more severe in the summer and improve significantly in the winter. What is the most appropriate diagnostic test for this condition?
- A. Patch test (Correct Answer)
- B. Skin biopsy
- C. Intradermal prick test
- D. Estimation of IgE levels in blood
Explanation: ### Explanation **Diagnosis: Parthenium Dermatitis (Airborne Contact Dermatitis)** The clinical presentation of itchy, erythematous papules in a "photo-distributed" pattern (face, neck, 'V' area of chest, and dorsum of hands/forearms) in a farmer, with seasonal exacerbation in summer, is classic for **Parthenium Dermatitis**. This is a type of **Airborne Contact Dermatitis (ABCD)** caused by the weed *Parthenium hysterophorus*. **1. Why Patch Test is the Correct Answer:** Parthenium dermatitis is a **Type IV (Delayed-type) Hypersensitivity reaction**. The gold standard for diagnosing Type IV hypersensitivity is the **Patch Test**. It identifies the specific allergen (usually the sesquiterpene lactone in Parthenium) responsible for the T-cell mediated allergic response. **2. Why Other Options are Incorrect:** * **Skin Biopsy:** While it may show features of eczematous dermatitis (spongiosis), it is non-specific and cannot identify the causative allergen. * **Intradermal Prick Test:** This is used to diagnose **Type I (Immediate) Hypersensitivity** (e.g., asthma, allergic rhinitis). It is not used for contact dermatitis. * **Estimation of IgE levels:** IgE is a marker for Type I hypersensitivity and atopic conditions. It has no diagnostic value in Type IV hypersensitivity reactions like ABCD. **Clinical Pearls for NEET-PG:** * **Distribution:** Unlike true photodermatitis, ABCD often involves the **upper eyelids, nasolabial folds, and retroauricular areas** (the "shadow regions"), as pollen/dust can settle there. * **Common Allergen:** In India, *Parthenium hysterophorus* (Congress grass) is the most common cause. * **Management:** Avoidance of the allergen is key. Topical steroids and sun protection are used for symptomatic relief. In chronic cases, azathioprine may be used as a steroid-sparing agent.
Question 9: Patch test is done to document which type of hypersensitivity?
- A. Type I hypersensitivity
- B. Delayed type hypersensitivity (Correct Answer)
- C. Autoimmune disease
- D. Immunocomplex deposition
Explanation: ### Explanation **Correct Answer: B. Delayed type hypersensitivity** The **Patch Test** is the gold standard diagnostic tool for **Allergic Contact Dermatitis (ACD)**. ACD is a classic example of **Type IV Hypersensitivity** (also known as Delayed-type Hypersensitivity). * **Mechanism:** This reaction is **T-cell mediated** (specifically Th1 cells) rather than antibody-mediated. When an allergen contacts the skin of a sensitized individual, memory T-cells recognize the antigen, leading to the release of cytokines and subsequent inflammation. * **Timing:** Because it takes time for T-cell recruitment and cytokine production, the reaction typically peaks at **48 to 72 hours**, which is why patch test readings are performed at these intervals. --- ### Why other options are incorrect: * **A. Type I Hypersensitivity:** This is an immediate, IgE-mediated reaction (e.g., Anaphylaxis, Urticaria). It is tested using the **Skin Prick Test**, not the Patch Test. * **C. Autoimmune Disease:** While some autoimmune skin diseases (like Pemphigus) are diagnosed via Immunofluorescence (DIF/IIF), the patch test specifically identifies external allergens, not auto-antibodies against self-antigens. * **D. Immunocomplex Deposition:** This refers to **Type III Hypersensitivity** (e.g., SLE, Vasculitis). These are typically diagnosed via skin biopsy and direct immunofluorescence showing granular deposits (e.g., Lumpy-bumpy pattern). --- ### High-Yield Facts for NEET-PG: * **Standard Series:** The most commonly used series globally is the **European Standard Series**; in India, it is the **ISDR (Indian Standard Series)**. * **Commonest Allergen:** Globally, **Nickel** (found in artificial jewelry) is the most common allergen. In India, **Parthenium** (Congress grass) is a frequent cause of airborne contact dermatitis. * **Reading Schedule:** Readings are usually taken at **48 hours** (removal of patches) and **72 or 96 hours** (delayed reading). * **Open Patch Test:** Used for substances with potential irritancy or volatile compounds.
Question 10: A 19-year-old man develops a rash in the groin area. On examination, it is a large well-demarcated area of tan-brown discoloration around his left inguinal area. There is some scaling of the lesion when brushed with a tongue depressor. Which of the following is the most appropriate initial diagnostic test?
- A. Punch biopsy of skin
- B. Tzanck smear
- C. Potassium hydroxide (KOH) preparation of scrapings (Correct Answer)
- D. Blood culture for fungi
Explanation: ### Explanation The clinical presentation of a **well-demarcated, tan-brown, scaly lesion** in the inguinal area of a young man is highly suggestive of a superficial fungal infection, most likely **Tinea cruris** (jock itch). **1. Why KOH Preparation is Correct:** The **Potassium Hydroxide (KOH) preparation** is the gold standard initial diagnostic test for suspected fungal infections of the skin. When skin scrapings are treated with 10–20% KOH, the alkaline solution dissolves keratinocytes and debris, allowing for the clear visualization of fungal elements like **septate hyphae** or spores under a microscope. The "scaling when brushed" (positive scratch sign) indicates active fungal shedding or associated pityriasis, making KOH the most efficient and cost-effective bedside tool. **2. Why Other Options are Incorrect:** * **Punch Biopsy:** This is an invasive procedure used for deep inflammatory conditions or suspected malignancies. It is not indicated for a simple, superficial scaly rash. * **Tzanck Smear:** This is used for the diagnosis of **herpetic infections** (HSV, VZV) to look for multinucleated giant cells, not fungal infections. * **Blood Culture:** This is used for systemic/disseminated fungal infections (e.g., Candidemia). Superficial dermatophytosis does not involve the bloodstream. **3. High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis:** If the lesion showed **coral-red fluorescence** under Wood’s lamp, the diagnosis would be **Erythrasma** (caused by *Corynebacterium minutissimum*). * **Tinea Cruris vs. Candidiasis:** Tinea cruris typically **spares the scrotum**, whereas Candidal intertrigo involves the scrotum and presents with **satellite lesions**. * **Treatment:** First-line treatment for localized Tinea cruris is topical antifungals (e.g., Clotrimazole, Terbinafine). Avoid topical steroids as they lead to **Tinea incognito**.
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