Cutaneous Immunology Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Cutaneous Immunology. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Cutaneous Immunology Indian Medical PG Question 1: What is the primary function of Langerhans' cells?
- A. Antigen presenting cells (Correct Answer)
- B. Involved in immune responses
- C. Phagocytosis of pathogens
- D. Keratinocyte production and maintenance
Cutaneous Immunology Explanation: ***Antigen presenting cells***
- Langerhans' cells play a critical role as **antigen presenting cells** (APCs) in the immune system, facilitating the activation of T-cells [1][2].
- They are found in the **epidermis** and are essential in initiating immune responses against pathogens [1][3].
*Seen in auto immune conditions*
- While Langerhans' cells may be involved in autoimmune responses, they are not exclusively seen in these conditions.
- Their primary function isn't linked to autoimmunity but rather to **immunological surveillance** and **antigen presentation** [1].
*Phagocytic cells*
- Langerhans' cells are not primarily **phagocytic**, as their main role focuses on presenting antigens rather than directly engulfing pathogens [1].
- Phagocytic cells include macrophages and neutrophils, which are more involved in **directly consuming foreign particles**.
*Seen in chronic infection*
- Although Langerhans' cells can participate in the immune response during infections, they are not specifically characterized as being prominent in **chronic infections**.
- Chronic infections are typically associated with different immune cell dynamics, involving other cells such as **plasma cells** and **T-cells**.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 200.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 207-208.
[3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1144.
Cutaneous Immunology Indian Medical PG Question 2: A 32 year old man presents with a 3-month history of weight loss, night sweats, a productive cough with blood-tinged sputum, anorexia, general malaise, and a low grade fever. A PPD skin test shows > 10 mm of induration. If the area of induration were biopsied, which of the following type of reactive cells would be found?
- A. Eosinophil
- B. T lymphocyte (Correct Answer)
- C. B lymphocyte
- D. Mast cell
Cutaneous Immunology Explanation: ***T lymphocyte***
- The clinical picture (weight loss, night sweats, productive cough with blood-tinged sputum, positive PPD) is highly suggestive of **tuberculosis**, a **Type IV hypersensitivity reaction** [1], [2].
- **Type IV hypersensitivity reactions** are cell-mediated, involving the activation of **T lymphocytes**, which migrate to the site of antigen exposure (like a PPD test site or a tuberculous granuloma) and release cytokines, leading to induration and inflammation [1], [2].
*Eosinophil*
- **Eosinophils** are primarily involved in allergic reactions and defense against parasitic infections [3].
- They are not the predominant reactive cells in a **Type IV hypersensitivity** response like that seen in tuberculosis [1].
*Mast cell*
- **Mast cells** play a critical role in immediate hypersensitivity reactions (Type I), releasing histamine and other mediators [4].
- They are not the primary cells involved in the delayed-type hypersensitivity response elicited by tuberculin purified protein derivative (PPD) [2].
*B lymphocyte*
- **B lymphocytes** are responsible for humoral immunity by producing antibodies [3].
- While they contribute to overall immune responses, they are not the main effector cells in a cell-mediated **Type IV hypersensitivity reaction** characteristic of a positive PPD test [1], [2].
**References:**
[1] 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. 173-174.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 218.
[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. 195-196.
[4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 208-210.
Cutaneous Immunology Indian Medical PG Question 3: A 60-year-old female presents with eczematous itching lesions. Biopsy revealed a subepidermal cleft with Direct Immunofluorescence showing Linear C3 & IgG deposition along the basement membrane zone. What is the likely diagnosis?
- A. Pemphigus foliaceus
- B. Pemphigus Vulgaris
- C. Dermatitis herpetiformis
- D. Bullous Pemphigoid (Correct Answer)
Cutaneous Immunology Explanation: ***Bullous Pemphigoid***
- The presence of **eczematous itching lesions**, a **subepidermal cleft**, and **linear C3 and IgG deposition along the basement membrane zone** on direct immunofluorescence (DIF) are classic diagnostic features of Bullous Pemphigoid.
- This autoimmune blistering disease typically affects older individuals and is characterized by antibodies targeting components of the **hemidesmosomes**, specifically BP180 and BP230.
*Pemphigus foliaceus*
- This condition involves **intraepidermal blistering**, specifically within the granular layer, rather than a subepidermal cleft.
- DIF in Pemphigus foliaceus shows **intercellular IgG deposition** in the epidermis, not linear deposition along the basement membrane zone.
*Pemphigus Vulgaris*
- Pemphigus Vulgaris is characterized by **intraepidermal blistering** above the basal cell layer (**suprabasal clefting**), leading to fragile bullae that rupture easily.
- DIF typically reveals **intercellular IgG and C3 deposition** in a "chicken wire" pattern throughout the epidermis, which differs from the linear pattern seen in this case.
*Dermatitis herpetiformis*
- While Dermatitis herpetiformis is also an autoimmune blistering disease with itching lesions, its characteristic DIF finding is **granular IgA deposition** in the dermal papillae, not linear C3 and IgG at the basement membrane zone.
- Histopathology in Dermatitis herpetiformis shows **subepidermal vesicles** with neutrophil infiltration in the dermal papillae, but the direct immunofluorescence pattern is distinct.
Cutaneous Immunology Indian Medical PG Question 4: 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
Cutaneous Immunology 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
Cutaneous Immunology Indian Medical PG Question 5: Most common precipitant of contact dermatitis is?
- A. Gold
- B. Silver
- C. Iron
- D. Nickel (Correct Answer)
Cutaneous Immunology Explanation: ***Nickel***
- **Nickel** is the most frequent cause of **allergic contact dermatitis**, commonly found in jewelry, belt buckles, and zippers.
- Exposure leads to a **Type IV hypersensitivity reaction**, characterized by erythema, itching, and vesiculation.
*Gold*
- While gold can cause contact dermatitis, it is **far less common** than nickel allergy.
- Reactions to gold are often seen with prolonged skin contact, such as with jewelry.
*Silver*
- **Silver** is a **rare cause** of allergic contact dermatitis.
- Allergic reactions to silver are typically observed in individuals with extensive exposure, such as jewelers.
*Iron*
- **Iron** is **not a common precipitant** of contact dermatitis.
- Allergic reactions to iron are exceedingly rare, as iron is an essential element found naturally in the body.
Cutaneous Immunology Indian Medical PG Question 6: In a patient with the following lesion on scalp, what changes are seen in the nails?
- A. Azure nails
- B. Dorsal pterygium of nails
- C. Pitting of nails (Correct Answer)
- D. Yellow nail discolouration
Cutaneous Immunology Explanation: ***Pitting of nails***
- The image shows a patch of **alopecia areata** on the scalp. **Nail pitting** is the most common and characteristic nail change associated with alopecia areata, occurring in **10-66% of cases**.
- Pitting appears as small depressions or **"ice-pick" marks** on the nail surface, resulting from defective nail matrix keratinization.
- Other nail changes in alopecia areata include **trachyonychia (rough nails), red spotted lunulae, onycholysis**, and **Beau's lines**.
*Dorsal pterygium of nails*
- **Dorsal pterygium** occurs when the proximal nail fold fuses with and extends over the nail plate, creating a wing-like scar.
- This is classically associated with **lichen planus, trauma, burns, vasculitis**, and **graft-versus-host disease** — **NOT alopecia areata**.
- It can lead to permanent nail dystrophy or nail loss.
*Azure nails*
- **Azure nails** (blue nails) are typically associated with **Wilson's disease** (copper accumulation) or **minocycline use**, not alopecia areata.
- They represent a blue-gray discoloration of the nail bed or lunula.
*Yellow nail discolouration*
- **Yellow nail syndrome** is a rare condition characterized by slow-growing, thickened, yellow nails, often associated with **lymphedema** and **respiratory problems** (pleural effusions, chronic bronchitis).
- It is not linked to alopecia areata.
Cutaneous Immunology Indian Medical PG Question 7: 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
Cutaneous Immunology 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
Cutaneous Immunology Indian Medical PG Question 8: Patient on anti-TB drugs develops tender nodules on shins. Most likely diagnosis is:
- A. Sweet syndrome
- B. Panniculitis
- C. Erythema multiforme
- D. Erythema nodosum (Correct Answer)
Cutaneous Immunology Explanation: ***Erythema nodosum***
- Erythema nodosum is a common **cutaneous adverse drug reaction** to anti-TB medications, presenting with **tender, erythematous nodules** typically on the shins.
- It is a form of **panniculitis** (inflammation of subcutaneous fat) specifically associated with various triggers, including infections and drugs, making it highly probable in this context.
*Sweet syndrome*
- Sweet syndrome (acute febrile neutrophilic dermatosis) presents with **tender, erythematous plaques and nodules** often associated with fever and leukocytosis.
- While it can be drug-induced, it typically involves a more widespread skin eruption and prominent systemic symptoms like **fever**, which are not specified here.
*Panniculitis*
- Panniculitis is a general term for **inflammation of the subcutaneous fat**, and erythema nodosum is a type of panniculitis.
- This option is too broad; while accurate, "Erythema nodosum" is the **most specific and likely diagnosis** given the patient’s presentation in the context of anti-TB drug use.
*Erythema multiforme*
- Erythema multiforme is characterized by **target lesions** (concentric rings of erythema and edema) and often involves mucous membranes.
- The description of **tender nodules on shins** does not fit the characteristic morphology of erythema multiforme.
Cutaneous Immunology Indian Medical PG Question 9: Lines of Blaschko are related to?
- A. Keratinocytes (Correct Answer)
- B. Blood vessels
- C. Nerves
- D. Bones
Cutaneous Immunology Explanation: ***Keratinocytes***
- **Lines of Blaschko** represent the migratory pathways of embryonic cells, primarily **keratinocytes**, in the skin.
- These lines are not visible under normal conditions but become apparent in various **genetic skin disorders** where abnormal cells follow these specific patterns.
*Blood vessels*
- While blood vessels are extensively present in the skin, they do not follow the specific **migratory patterns** described by the Lines of Blaschko.
- Their arrangement is more related to **vascular networks** and anatomical supply rather than embryonic cell migration.
*Nerves*
- **Nerves** in the skin have specific distributions, often following dermatomal patterns, which are distinct from the **Lines of Blaschko**.
- Nerve distribution is related to their segmental origin from the **spinal cord**, not the migratory paths of epidermal cells.
*Bones*
- **Bones** are part of the skeletal system and are not found in the skin, making them unrelated to the **Lines of Blaschko**.
- These lines describe epidermal cell migration, which is a feature of the **integumentary system**.
Cutaneous Immunology Indian Medical PG Question 10: Which sign is pathognomonic for neurofibromatosis?
- A. Cafe-au-lait macules
- B. Axillary freckling (Correct Answer)
- C. Shagreen patch
- D. None of the above
Cutaneous Immunology Explanation: **Explanation:**
**Neurofibromatosis Type 1 (NF1)**, also known as von Recklinghausen disease, is an autosomal dominant multisystem disorder. The correct answer is **Axillary freckling (Crowe sign)** because it is considered highly specific (pathognomonic) for NF1.
1. **Axillary Freckling (Crowe Sign):** These are small, 1–3 mm hyperpigmented macules found in intertriginous areas (axilla or groin). Unlike solar lentigines, they appear in areas not exposed to the sun. Their presence is a hallmark diagnostic criterion for NF1.
2. **Cafe-au-lait macules (CALMs):** While these are often the first sign of NF1, they are **not pathognomonic**. CALMs can be seen in healthy individuals, McCune-Albright syndrome, Fanconi anemia, and Legius syndrome. In NF1, the presence of 6 or more macules (>5mm in prepubertal; >15mm in postpubertal) is required for diagnosis.
3. **Shagreen patch:** This is a connective tissue nevus (leathery plaque) typically found on the lower back. It is a characteristic feature of **Tuberous Sclerosis**, not Neurofibromatosis.
**High-Yield Clinical Pearls for NEET-PG:**
* **Lisch Nodules:** Iris hamartomas (seen on slit-lamp exam) are the most common ocular finding in NF1.
* **Optic Glioma:** The most common CNS tumor associated with NF1.
* **Sphenoid Wing Dysplasia:** A classic skeletal deformity in NF1.
* **Genetics:** NF1 is caused by a mutation in the *NF1* gene on **Chromosome 17** (encodes Neurofibromin), while NF2 is linked to **Chromosome 22** (encodes Merlin).
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