Skin Biopsy Techniques — MCQs
What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
The best site for taking a biopsy for viral esophagitis is:
Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
A child presents with grouped vesicles on the lips. What is the bedside investigation that you would like to do?
Shave biopsy is not done in:
What is the first-line treatment for melasma?
Which of the following is best for ante-mortem diagnosis of rabies?
A young lady presented with bilateral nodular lesions on shins. She was also found to have bilateral hilar lymphadenopathy on chest X-ray. Mantoux test reveals indurations of 5 mms. Skin biopsy would reveal:
Which of the following are true about epidermal cyst? 1. It is lined by stratified squamous epithelium. 2. It is derived from hair follicle. 3. It contains keratin debris. 4. It is not fixed to the skin.
Unna boot is used for the treatment of which condition?
Skin Biopsy Techniques Indian Medical PG Practice Questions and MCQs
Question 1: What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
- A. Melanocytic nevus
- B. Becker nevus (Correct Answer)
- C. Sebaceous nevus
- D. Comedo nevus
Explanation: ***Correct: Becker nevus*** This diagnosis is supported by the description of a **hyperpigmented lesion** that is **enlarging** and has **hair growing from it**, typically appearing during adolescence or young adulthood. **Becker nevus** often presents as an **irregular, hyperpigmented patch**, usually on the shoulder or upper trunk, and is characteristically associated with **hypertrichosis** (increased terminal hair growth). The combination of location (shoulder), enlargement, and hair growth in a 15 mm lesion is classic for Becker nevus. *Incorrect: Melanocytic nevus* While **melanocytic nevi** are hyperpigmented, they typically do not continue to **enlarge significantly** after childhood and generally do not develop new onset **hypertrichosis** as a primary feature. The size (15 mm) and progressive growth combined with hair development are more characteristic of a Becker nevus than a common melanocytic nevus. *Incorrect: Sebaceous nevus* **Sebaceous nevi** are typically **yellow-orange to tan, waxy plaques**, often on the scalp or face, with a cobblestone or papillomatous texture. They are not primarily characterized by **hyperpigmentation** and terminal hair growth, but rather by sebaceous gland proliferation. *Incorrect: Comedo nevus* A **comedo nevus** presents as a linear or unilateral group of **dilated follicular openings** filled with keratinous material, resembling blackheads. It is not characterized by diffuse **hyperpigmentation** or the increased terminal hair growth described in this case.
Question 2: The best site for taking a biopsy for viral esophagitis is:
- A. Adjacent indurated area around ulcer
- B. Surrounding normal mucosa
- C. Base of ulcer
- D. Edge of ulcer (Correct Answer)
Explanation: ***Edge of ulcer*** - The **edge of the ulcer** is the ideal biopsy site for viral esophagitis as it contains **viable infected epithelial cells** with characteristic viral cytopathic effects. - In **HSV esophagitis**, Cowdry type A intranuclear inclusions are found in epithelial cells at the **ulcer margin**; in **CMV esophagitis**, characteristic "owl's eye" inclusions are seen in enlarged cells at the **ulcer edge**. - Viable epithelial cells at the periphery are actively infected and show diagnostic histological features, making them suitable for **immunohistochemistry** and **PCR confirmation**. - Standard pathology teaching (Robbins, WHO) emphasizes biopsying the **ulcer edge** where the virus is actively replicating in living cells. *Base of ulcer* - The **base of the ulcer** primarily contains necrotic debris, fibrin, inflammatory exudate, and dead cells—not viable epithelial cells. - Since viral inclusions are found in **nuclei of living epithelial cells**, the necrotic base is an inappropriate biopsy site and unlikely to yield diagnostic findings. - The base lacks the cellular architecture needed to identify characteristic viral cytopathic effects. *Adjacent indurated area around ulcer* - An **indurated area** suggests chronic inflammation or fibrosis, which may be secondary to the viral infection but is not the primary site of active viral replication. - This area is less likely to show the diagnostic viral inclusions compared to the ulcer edge with viable infected epithelium. *Surrounding normal mucosa* - **Normal surrounding mucosa** does not show pathological changes related to the viral infection. - Biopsying normal-appearing tissue would not provide diagnostic material and would miss the characteristic features of viral esophagitis.
Question 3: Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
- A. Statements 1 & 2 are correct, 2 is not explaining 1 (Correct Answer)
- B. Statements 1 and 2 are correct and 2 is the correct explanation for 1
- C. Statements 1 and 2 are incorrect
- D. Statement 1 is incorrect
Explanation: ***Correct: Statements 1 & 2 are correct, 2 is not explaining 1*** **Analysis of Statement 1:** - A 59-year-old patient with **flaccid bullae** and **suprabasal acantholytic split** on histopathology is the classic presentation of **Pemphigus vulgaris** - The flaccid (easily ruptured) nature of bullae distinguishes it from tense bullae seen in bullous pemphigoid - The suprabasal location of the split (just above the basal layer) with acantholysis (loss of cell-to-cell adhesion) is pathognomonic - **Statement 1 is CORRECT** ✓ **Analysis of Statement 2:** - The **"row of tombstones" or "tombstone appearance"** is indeed a diagnostic histopathological feature of Pemphigus vulgaris - This appearance results from basal keratinocytes remaining attached to the basement membrane while suprabasal cells separate due to acantholysis - The intact basal cells standing upright resemble a row of tombstones - **Statement 2 is CORRECT** ✓ **Does Statement 2 explain Statement 1?** - Statement 2 describes a **histopathological appearance** (tombstone pattern) that is a **consequence** of the suprabasal split - However, it does NOT explain the **underlying cause** of the flaccid bullae or the suprabasal split - The true explanation involves **IgG autoantibodies against desmoglein 3 (and desmoglein 1)**, which attack intercellular adhesion structures (desmosomes), causing **acantholysis** - Therefore, **Statement 2 does NOT explain Statement 1** ✗ *Incorrect: Statement 2 is the correct explanation for Statement 1* - While both statements describe features of Pemphigus vulgaris, the tombstone appearance is a descriptive finding, not an explanatory mechanism *Incorrect: Statements 1 and 2 are incorrect* - Both statements are medically accurate descriptions of Pemphigus vulgaris features *Incorrect: Statement 1 is incorrect* - Statement 1 correctly describes the cardinal clinical and histopathological features of Pemphigus vulgaris
Question 4: A child presents with grouped vesicles on the lips. What is the bedside investigation that you would like to do?
- A. Wood's lamp
- B. Slit skin smear
- C. Tzanck smear (Correct Answer)
- D. KOH
Explanation: ***Tzanck smear*** - A **Tzanck smear** is a rapid bedside test that can identify **multinucleated giant cells**, which are seen in herpes simplex virus infections. - The presence of **grouped vesicles on the lips** is highly suggestive of **herpes labialis** (HSV-1), which is primarily a **clinical diagnosis**. - Among the options provided, Tzanck smear is the only relevant bedside investigation, though it has **limited sensitivity and specificity** and **cannot distinguish between HSV and VZV**. - In modern practice, **PCR or direct immunofluorescence** are preferred when laboratory confirmation is needed, but Tzanck smear remains a low-cost option in resource-limited settings. *Wood's lamp* - A Wood's lamp uses **ultraviolet light** to detect certain fungal or bacterial infections by revealing characteristic fluorescence. - It is useful for conditions like **tinea capitis** (green fluorescence) and **erythrasma** (coral-red fluorescence), but has no role in diagnosing viral vesicular lesions. *Slit skin smear* - A **slit skin smear** is used to detect **acid-fast bacilli** in the diagnosis of **leprosy**. - It is not indicated for vesicular lesions and is irrelevant to herpes simplex infection. *KOH* - A **KOH (potassium hydroxide) mount** is used to diagnose **fungal infections** by dissolving keratinocytes and revealing fungal hyphae or spores. - It has no utility in diagnosing viral infections such as herpes simplex.
Question 5: Shave biopsy is not done in:
- A. Seborrheic keratoses
- B. Basal cell carcinoma
- C. Melanoma (Correct Answer)
- D. Viral warts
Explanation: ***Melanoma*** - **Shave biopsy is absolutely contraindicated for suspected melanoma** because it does not provide sufficient depth to accurately measure **Breslow thickness**, which is the most important prognostic factor. - An **excisional biopsy with 1-3mm margins** down to subcutaneous fat is the gold standard to ensure complete histological evaluation and accurate staging. - Inadequate depth sampling can lead to **understaging, incorrect prognosis, and inappropriate treatment planning**. *Basal cell carcinoma* - Shave biopsy **can be performed** for basal cell carcinoma and is commonly used for diagnostic purposes, especially for **superficial and nodular types**. - While punch or excisional biopsy may be preferred for morpheaform or infiltrative subtypes to assess depth, shave biopsy is not contraindicated and provides adequate tissue for diagnosis in most cases. *Seborrheic keratoses* - **Shave biopsy is ideal** for seborrheic keratoses as they are **benign, superficial epidermal growths**. - The technique allows for complete removal and histological confirmation with excellent cosmetic outcomes. *Viral warts* - **Shave biopsy can be used** for diagnosis and treatment of viral warts, particularly for **exophytic lesions**. - The superficial nature of warts makes shave excision an appropriate and effective method.
Question 6: What is the first-line treatment for melasma?
- A. Laser therapy
- B. Topical hydroquinone (Correct Answer)
- C. Chemical peels
- D. Microdermabrasion
Explanation: ***Topical hydroquinone*** - **Topical hydroquinone** (2-4%) is the **most effective single-agent treatment** among the given options, serving as the gold standard for melasma by inhibiting **tyrosinase enzyme** and melanin production. - Demonstrates **highest efficacy rates** (60-80% improvement) when combined with strict sun protection, making it both first-line and most effective monotherapy choice. *Laser therapy* - Carries **high risk of paradoxical darkening** and post-inflammatory hyperpigmentation, especially in darker skin types common in melasma patients. - Requires **specialized expertise** and should only be considered as adjunctive therapy after optimizing topical treatments, not as primary treatment. *Chemical peels* - Provide **variable and inconsistent results** as monotherapy, typically requiring multiple sessions with unpredictable outcomes. - Risk of **post-inflammatory hyperpigmentation** particularly in Fitzpatrick skin types IV-VI, making them less reliable than hydroquinone. *Microdermabrasion* - Offers only **superficial exfoliation** with minimal clinical improvement in melasma pigmentation. - May actually **worsen pigmentation** through mechanical irritation and is not recommended in evidence-based treatment guidelines.
Question 7: Which of the following is best for ante-mortem diagnosis of rabies?
- A. Immunofluorescence of corneal impressions
- B. Isolation of virus from saliva
- C. Immunofluorescence of skin biopsy (Correct Answer)
- D. Antirabies antibodies in blood
Explanation: ***Immunofluorescence of skin biopsy*** - This method involves taking a **skin biopsy** from the **nuchal area** (nape of the neck) and staining it with **fluorescently labeled antibodies** to detect **rabies viral antigens** in cutaneous nerves. - It is considered the most reliable ante-mortem diagnostic test for rabies due to its high specificity and sensitivity in detecting viral nucleocapsid protein. *Immunofluorescence of corneal impressions* - While this method can detect rabies antigens, it generally has **lower sensitivity** compared to skin biopsy. - The procedure can be technically challenging and may yield **false negatives**, especially in early stages of the disease. *Isolation of virus from saliva* - **Viral isolation from saliva** is a possible method, but it is **less sensitive** and **more time-consuming** than immunological detection. - The shedding of rabies virus in saliva can be **intermittent**, leading to potential false negatives. *Antirabies antibodies in blood* - The presence of **antirabies antibodies in the blood** usually indicates either prior vaccination or a late stage of infection where the immune system has begun to respond. - These antibodies are often **undetectable in the early stages** of rabies infection, making this test unreliable for early ante-mortem diagnosis.
Question 8: A young lady presented with bilateral nodular lesions on shins. She was also found to have bilateral hilar lymphadenopathy on chest X-ray. Mantoux test reveals indurations of 5 mms. Skin biopsy would reveal:
- A. Malignant cells
- B. Caseating Granuloma
- C. Vasculitis
- D. Non caseating Granuloma (Correct Answer)
Explanation: **Non-caseating Granuloma** * The constellation of **bilateral nodular lesions on shins** (consistent with erythema nodosum) and **bilateral hilar lymphadenopathy** is highly suggestive of **sarcoidosis**. * **Skin biopsy** in sarcoidosis typically shows **non-caseating granulomas**, which are collections of macrophages without central necrosis [1]. *In this context, the Mantoux test result (5 mm induration) is equivocal/negative, which further supports sarcoidosis over tuberculosis. *Malignant cells* * While some malignancies can cause skin lesions and lymphadenopathy, the specific pattern of **erythema nodosum** and **bilateral hilar lymphadenopathy** is not characteristic of primary malignancy. * A biopsy showing malignant cells would indicate a different underlying pathology, which is less likely given the classic presentation. *Caseating Granuloma* * **Caseating granulomas** are the hallmark of **tuberculosis** and certain fungal infections, characterized by central necrosis. * Although tuberculosis can cause hilar lymphadenopathy, the presence of **erythema nodosum** and the absence of clear signs of active tuberculosis (e.g., positive Mantoux, constitutional symptoms) make it less likely. *Vasculitis* * **Vasculitis** involves inflammation of blood vessels and can manifest with various skin lesions (e.g., purpura, nodules, ulcers) but generally does not present with **bilateral hilar lymphadenopathy** as a primary feature. * The clinical picture is more consistent with a granulomatous inflammatory process affecting the skin and lymph nodes, not primarily vasculitic changes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 700-701.
Question 9: Which of the following are true about epidermal cyst? 1. It is lined by stratified squamous epithelium. 2. It is derived from hair follicle. 3. It contains keratin debris. 4. It is not fixed to the skin.
- A. 1, 3 and 4
- B. 1, 2 and 4
- C. 2, 3 and 4
- D. 1, 2 and 3 (Correct Answer)
Explanation: ***1, 2 and 3*** - An **epidermal cyst** is indeed derived from the **infundibulum of a hair follicle**. - It is lined by **stratified squamous epithelium** and contains **keratin debris**, giving it a cheesy consistency. *1, 3 and 4* - While an epidermal cyst is lined by stratified squamous epithelium and contains keratin, it is often **fixed to the skin** due to its attachment to the follicular opening, making statement 4 incorrect. - The cyst's connection to the surface epithelium is a distinguishing feature, preventing it from being freely mobile. *1, 2 and 4* - Although statements 1 and 2 are true, statement 4, claiming it is not fixed to the skin, is generally **incorrect**. - Epidermal cysts typically have a punctum or small opening to the skin surface, indicating its attachment. *2, 3 and 4* - Statements 2 and 3 are correct, but statement 4, suggesting it is not fixed, is **false**. - The presence of a **central punctum**, which is common in epidermal cysts, signifies its epidermal origin and attachment to the skin.
Question 10: 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.
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