Basic Dermatology Practice Questions

Q: The herald patch is typically associated with which dermatological condition?

Pityriasis rosea. **Explanation:** **Pityriasis Rosea (PR)** is a self-limiting, inflammatory skin disorder characterized by the **Herald Patch** (also known as the "Mother Patch"). This is the initial lesion, appearing in about 50–90% of cases. It is typically a single, oval, salmon-colored or erythematous plaque (2–10 cm) with a peripheral "collarette" of scale. Following this, a generalized eruption occurs along the cleavage lines (Langer’s lines), creating the classic **"Christmas Tree" appearance** on the back. It is thought to be associated with the reactivation of Human Herpesvirus 6 or 7 (HHV-6/7). **Why the other options are incorrect:** * **Psoriasis:** Characterized by well-demarcated erythematous plaques with silvery-white scales. Key features include **Auspitz sign** and **Koebner phenomenon**, but it does not feature a herald patch. * **Lichen Planus:** Presents as the "6 Ps" (Planar, Purple, Polygonal, Pruritic, Papules, and Plaques). It is noted for **Wickham striae** (white reticular patterns) rather than a precursor patch. * **Tinea Versicolor:** A fungal infection caused by *Malassezia furfur*. It presents as hypo- or hyperpigmented macules with fine scaling (**spaghetti and meatballs appearance** on KOH mount), but lacks the herald patch and Christmas tree distribution. **High-Yield Clinical Pearls for NEET-PG:** * **Collarette of scale:** The scale is attached at the periphery and directed inwards. * **Distribution:** Primarily affects the trunk; the face and distal extremities are usually spared. * **Treatment:** Reassurance is key as it is self-limiting (resolves in 6–8 weeks). Severe itching can be managed with antihistamines or topical steroids. * **Differential Diagnosis:** Secondary syphilis (always rule out if lesions appear on palms and soles).

Q: A female patient presents with bilateral buccal reticulate white streaks. The pain increases upon intake of spicy food. The patient denies any history of tobacco use but has amalgam fillings on her third molars. What is the most likely diagnosis?

Lichen planus. **Explanation:** The clinical presentation of bilateral, reticulate (net-like) white streaks on the buccal mucosa is the classic description of **Wickham’s striae**, which is pathognomonic for **Oral Lichen Planus (OLP)**. The exacerbation of pain with spicy food suggests the erosive or atrophic component of the disease. Notably, the presence of **amalgam fillings** is a high-yield trigger; dental restorative materials can induce a "lichenoid reaction" via a Type IV hypersensitivity response. **Why other options are incorrect:** * **Leukoplakia:** Typically presents as a solitary, well-demarcated white patch that cannot be scraped off. It is usually unilateral and strongly associated with tobacco use, which is absent here. * **Aphthous Stomatitis:** Presents as painful, recurrent, well-defined round ulcers with a yellowish floor and erythematous halo. It does not present with reticulate white streaks. * **Candidiasis (Thrush):** Presents as "curdy" white plaques that **can be scraped off**, leaving an erythematous or bleeding base. It is common in immunocompromised states or after antibiotic use. **NEET-PG High-Yield Pearls:** * **Histopathology:** Look for "saw-tooth" rete ridges, basal cell degeneration (liquefaction necrosis), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Civatte Bodies:** These are apoptotic keratinocytes found in the basal layer. * **Koebner Phenomenon:** Lichen planus is "Koebner positive" (lesions appear at sites of trauma). * **Treatment:** Topical corticosteroids (e.g., Clobetasol or Triamcinolone oral paste) are the first-line treatment.

Q: Which diagnostic procedure involves applying pressure to a suspected lesion to visualize the evacuation of its coloration?

Diascopy. **Explanation:** **Diascopy** is a simple bedside diagnostic technique used to determine if a skin lesion is **vascular (blanchable)** or **extravasated (non-blanchable)**. The procedure involves pressing a clear glass slide or a plastic plate (diascope) against the lesion. * **Mechanism:** Pressure causes the blood vessels to empty. If the redness disappears (**blanches**), it indicates dilated capillaries (e.g., erythema, telangiectasia, or hemangiomas). If the redness persists, it indicates **extravasation of red blood cells** into the dermis (e.g., purpura, petechiae, or ecchymosis). **Analysis of Incorrect Options:** * **A. Fluoroscopy:** An imaging technique that uses X-rays to obtain real-time moving images of the interior of an object (e.g., guiding catheters or viewing GI motility). * **C. Arthroscopy:** A minimally invasive surgical procedure used to visualize, diagnose, and treat problems inside a joint using an endoscope. * **D. Endoscopy:** A general term for a procedure where an instrument (endoscope) is introduced into the body to view internal organs or cavities (e.g., Gastroscopy). **Clinical Pearls for NEET-PG:** 1. **Apple-Jelly Nodules:** Diascopy is classically used to identify the "apple-jelly" appearance (yellowish-brown color) in **Lupus Vulgaris** (cutaneous tuberculosis) and Sarcoidosis. 2. **Granulomatous diseases:** The pressure of the slide reveals the underlying granulomatous infiltrate once the vascular component is compressed. 3. **Purpura vs. Erythema:** This is the most common clinical application; purpura does **not** blanch under pressure.

Q: Which of the following statements is NOT true about erythema nodosum?

Non-tender nodules. **Erythema Nodosum (EN)** is the most common form of clinico-pathological panniculitis (inflammation of subcutaneous fat). It is considered a delayed-type hypersensitivity reaction to various antigens. ### **Explanation of Options** * **B. Non-tender nodules (Correct Answer):** This statement is **false**. Erythema nodosum is characterized by **exquisitely tender**, erythematous, warm nodules. The pain is often out of proportion to the clinical appearance, making "non-tender" the incorrect descriptor. * **A. Seen over the anterior aspect of the legs:** This is a classic clinical feature. EN typically presents as symmetrical, poorly defined nodules over the **pretibial area** (shins). * **C. More common in females:** EN shows a strong female predilection, with a female-to-male ratio of approximately **3:1 to 6:1**, particularly in the second to fourth decades of life. * **D. Involution occurs in three to six weeks:** EN is usually self-limiting. The nodules undergo a characteristic color change (resembling a bruise, known as *erythema contusiformis*) and typically resolve without scarring or atrophy within **3 to 6 weeks**. ### **NEET-PG High-Yield Pearls** 1. **Histopathology:** The hallmark is **Septal Panniculitis** without vasculitis. Look for **Miescher’s radial granulomas** (small aggregates of spindle-shaped histiocytes around a central cleft). 2. **Etiology:** The most common cause worldwide is **Idiopathic**. However, identifiable triggers include: * **Infections:** Streptococcal pharyngitis (most common in children), Primary TB, Leprosy (Type 2 reaction/ENL), Sarcoidosis (Lofgren’s Syndrome). * **Drugs:** Oral Contraceptive Pills (OCPs), Sulfonamides. * **Others:** Inflammatory Bowel Disease (IBD), Pregnancy. 3. **Lofgren’s Syndrome:** A specific triad of Erythema Nodosum, bilateral hilar adenopathy, and polyarthritis (highly suggestive of Sarcoidosis).

Q: A patient presents with hyperhidrosis and clubbing of the fingers. What is the most likely diagnosis?

Pachydermoperiostosis. **Explanation:** **Pachydermoperiostosis (PDP)**, also known as Primary Hypertrophic Osteoarthropathy, is a rare genetic disorder characterized by a classic clinical triad: **pachydermia** (thickening of the skin), **periostitis** (new bone formation), and **finger clubbing**. The presence of **hyperhidrosis** (excessive sweating) is a highly characteristic feature of this condition, often occurring due to hypertrophy of the sweat glands and autonomic dysfunction. **Analysis of Options:** * **Pachydermoperiostosis (Correct):** It fits the clinical picture perfectly. Patients often present with "cutis verticis gyrata" (furrowing of the scalp), seborrhea, and significant enlargement of the hands and feet due to digital clubbing and periosteal proliferation. * **Acromegaly:** While it presents with skin thickening and enlarged extremities, it is caused by excess Growth Hormone. It typically lacks the specific periostitis and the classic triad seen in PDP. * **Rheumatoid Arthritis:** This is an inflammatory joint disease characterized by symmetrical small joint involvement and morning stiffness. It does not typically present with clubbing or generalized hyperhidrosis. * **Periostitis:** This is a clinical sign (inflammation of the periosteum) rather than a diagnosis. While it is a *component* of PDP, it does not explain the systemic finding of hyperhidrosis. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Usually Autosomal Dominant (SLCO1B1 gene mutation). * **Radiology:** Look for symmetrical, shaggy subperiosteal new bone formation, especially in distal long bones. * **Differential:** Secondary Hypertrophic Osteoarthropathy is usually associated with underlying lung malignancy or cyanotic heart disease; PDP is the primary/idiopathic form. * **Key Triad:** Pachydermia + Periostitis + Finger Clubbing.

Q: Phrynoderma is due to deficiency of which nutrient?

Essential fatty acids. **Explanation:** **Phrynoderma** (also known as "toad skin") is a form of follicular hyperkeratosis. While historically attributed primarily to Vitamin A deficiency, modern nutritional science and recent clinical studies have established that **Essential Fatty Acid (EFA) deficiency** (specifically linoleic and alpha-linolenic acid) is the primary etiological factor. EFAs are crucial for maintaining the epidermal water barrier and normal keratinization; their absence leads to the characteristic "nutmeg grater" appearance of the skin. **Analysis of Options:** * **Essential Fatty Acids (Correct):** Deficiency leads to follicular papules with central keratotic plugs, typically seen on the extensors of extremities, shoulders, and buttocks. It often responds better to EFA supplementation than to Vitamin A alone. * **Vitamin A:** While Vitamin A deficiency can cause similar skin changes, it is more classically associated with ocular signs (Bitot’s spots, Xerophthalmia). Phrynoderma in Vitamin A deficiency is often a secondary manifestation of generalized malnutrition. * **Niacin (Vitamin B3):** Deficiency causes **Pellagra**, characterized by the "3 Ds": Dermatitis (photosensitive Casal’s necklace), Diarrhea, and Dementia. * **Vitamin D:** Deficiency primarily affects bone mineralization (Rickets in children, Osteomalacia in adults) and does not typically present with follicular hyperkeratosis. **Clinical Pearls for NEET-PG:** 1. **Morphology:** Discrete, pinhead-sized follicular papules with **intrafollicular keratotic plugs**. 2. **Distribution:** Most common on the **elbows, knees, and extensor surfaces** of the extremities. 3. **Key Differential:** Keratosis Pilaris (genetic, usually starts in childhood, involves cheeks and upper arms). 4. **Treatment:** Supplementation with Safflower oil, Sunflower oil, or fish oils rich in EFAs.

Q: Erythema nodosum is not seen in which of the following conditions?

Giant cell arteritis. **Explanation:** **Erythema Nodosum (EN)** is the most common form of **septal panniculitis** (inflammation of the subcutaneous fat). It is a delayed-type hypersensitivity reaction to various systemic stimuli. **Why Giant Cell Arteritis (GCA) is the correct answer:** Giant cell arteritis is a large-vessel vasculitis. While it involves granulomatous inflammation of arteries, it is **not** typically associated with Erythema Nodosum. EN is associated with certain autoimmune conditions like Sarcoidosis and Inflammatory Bowel Disease (IBD), but not usually with primary systemic vasculitides like GCA. **Analysis of Incorrect Options:** * **Primary Tuberculosis:** Infections are the most common triggers for EN. In India, TB is a very high-yield cause. EN often appears during the primary stage of infection as an immunological response. * **Sulfonamides:** Drugs are the second most common cause of EN. Sulfonamides, oral contraceptives, and bromides are classic pharmacological triggers. * **Streptococcal Infection:** Globally, post-streptococcal pharyngitis is the most common infectious cause of EN, especially in children and young adults. **NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Painful, erythematous, non-ulcerating nodules, typically on the pretibial area (shins). * **Histopathology:** The hallmark is **septal panniculitis** without vasculitis. Look for **Miescher’s radial granulomas** (small nodules of spindle-shaped cells around a central cleft). * **Mnemonic for Causes (SHIPS):** **S**treptococcus, **H**istoplasmosis (and other fungi), **I**BD/Idiopathic, **P**regnancy/Pharmacology (Sulfonamides/OCPs), **S**arcoidosis/Sulfonamides. * **Lofgren’s Syndrome:** A specific triad of Erythema Nodosum, bilateral hilar lymphadenopathy, and polyarthritis (highly suggestive of Sarcoidosis).

Q: Which of the following conditions does NOT exhibit Koebner phenomenon?

Vitiligo. The **Koebner phenomenon** (also known as the isomorphic response) refers to the development of new skin lesions of a pre-existing dermatosis at the site of local trauma or injury to previously healthy skin. **Explanation of the Correct Answer:** While **Vitiligo** is traditionally listed in many textbooks as showing the Koebner phenomenon, it is technically considered a **"Pseudo-Koebner"** or "Questionable Koebner" phenomenon in advanced dermatology literature. However, in the context of this specific question and standard NEET-PG patterns, the focus is on identifying the most classic examples. *Correction/Clarification:* In standard clinical practice, Psoriasis, Lichen Planus, and Vitiligo **all** exhibit Koebnerization. If this question is presented with these options, it is often considered a "controversial" or "faulty" question because all four options (A, B, C, and D) are classic examples of the phenomenon. However, if forced to choose the "least likely" or if the question intended to test **Reverse Koebner** (where trauma causes a lesion to disappear), Vitiligo is sometimes the distractor. **Analysis of Incorrect Options:** * **Psoriasis (C):** The most classic example. Trauma (scratching) leads to new psoriatic plaques. * **Lichen Planus (A):** Frequently exhibits linear lesions due to scratching (Wickham striae may be visible). * **Warts (B):** Exhibits **Pseudo-Koebnerization**, where the virus is mechanically inoculated into the trauma site (e.g., linear warts from scratching). **High-Yield Clinical Pearls for NEET-PG:** * **True Koebner:** Psoriasis, Lichen Planus, Vitiligo, Pityriasis Rubra Pilaris (PRP). * **Pseudo-Koebner (Infectious):** Warts (HPV), Molluscum Contagiosum. * **Reverse Koebner:** Psoriasis, Vitiligo (lesion clears after trauma). * **Wolf’s Isotopic Response:** New disease appearing at the site of a healed unrelated disease (e.g., Granuloma annulare at the site of healed Herpes Zoster).

Q: A 20-year-old female presents with itchy, violaceous, shiny, flat-topped, polygonal papules on the flexor surface of the wrist. Examination under a magnifying lens reveals fine streaks on the lesion surface, enhanced by mineral oil. Koebner's phenomenon is present. Oral mucosa shows some lesions, including erosive lesions on the tongue. Nails exhibit thinning, distal splitting, longitudinal ridging, and pterygium. What is the most likely diagnosis?

Lichen planus. **Explanation:** The clinical presentation is a classic description of **Lichen Planus (LP)**, a chronic inflammatory condition of the skin and mucous membranes. **Why Option A is correct:** The diagnosis is confirmed by the presence of the **"6 Ps"**: Planar (flat-topped), Purple (violaceous), Polygonal, Pruritic, Papules, and Plaques. * **Wickham Striae:** The "fine streaks" on the surface enhanced by mineral oil are pathognomonic for LP, representing focal thickening of the granular layer. * **Distribution:** Predilection for **flexor surfaces** (wrists) and oral involvement (erosive tongue lesions) is typical. * **Nail Changes:** Longitudinal ridging, thinning, and especially **dorsal pterygium** (fusion of the proximal nail fold to the nail bed) are high-yield diagnostic markers for nail LP. * **Koebner’s Phenomenon:** Development of lesions at sites of trauma is common in LP. **Why other options are incorrect:** * **Lichenoid Eruption:** Usually drug-induced; lesions are typically more generalized, symmetric, and lack Wickham striae. * **Lichen Nitidus:** Characterized by tiny, skin-colored, "pinhead-sized" shiny papules. It does not typically involve the oral mucosa or cause pterygium. * **Discoid Lupus Erythematosus (DLE):** Presents with well-defined erythematous plaques with adherent scales and follicular plugging. It leads to scarring alopecia and atrophy, not the 6 Ps of LP. **NEET-PG High-Yield Pearls:** * **Histopathology:** Characterized by "saw-tooth" rete ridges, Civatte bodies (apoptotic keratinocytes), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Max-Joseph Clefts:** Small spaces between the epidermis and dermis due to basal cell degeneration. * **Associations:** Often associated with **Hepatitis C infection**. * **Treatment:** Topical steroids are first-line; systemic steroids or phototherapy for extensive disease.

Q: Migratory necrolytic erythema is seen in all conditions, except:

Hepatitis C. **Explanation:** **Migratory Necrolytic Erythema (MNE)** is a classic paraneoplastic cutaneous marker most commonly associated with a **Glucagonoma** (alpha-cell tumor of the pancreas). However, when MNE occurs in the absence of a pancreatic tumor, it is termed **"Pseudoglucagonoma Syndrome."** 1. **Why Hepatitis C is the correct answer:** While MNE is associated with various systemic conditions, **Hepatitis C** is specifically associated with **Necrolytic Acral Erythema (NAE)**, not Migratory Necrolytic Erythema. NAE is considered a pathognomonic cutaneous marker for Hepatitis C infection and presents with pruritic, lichenified plaques primarily on the dorsal aspects of the feet. 2. **Analysis of other options (Causes of Pseudoglucagonoma Syndrome):** * **Hepatitis B:** Chronic liver diseases, including Hepatitis B and cirrhosis, can lead to MNE due to hypoalbuminemia and altered metabolism of amino acids and zinc. * **Short Bowel Syndrome:** Malabsorption syndromes (like short bowel or Celiac disease) lead to severe deficiencies in zinc, essential fatty acids, and amino acids, which are implicated in the pathogenesis of MNE. * **Myeloproliferative Disorders:** Rare cases of MNE have been reported in association with internal malignancies and hematological disorders like myelodysplastic syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Glucagonoma Syndrome Triad:** MNE, Diabetes Mellitus (glucose intolerance), and Weight loss. * **Histopathology of MNE:** Characterized by **necrosis of the upper epidermis** (sudden lysis of keratinocytes in the granular layer). * **Key Lab Finding:** Profound **hypoaminoacidemia** is a hallmark of the condition. * **NAE vs. MNE:** Always associate **Necrolytic Acral Erythema** with **Hepatitis C** and **Migratory Necrolytic Erythema** with **Glucagonoma**.

Question 1

The herald patch is typically associated with which dermatological condition?

Accepted Answer

Pityriasis rosea

Answer

Psoriasis

Answer

Lichen planus

Answer

Tinea versicolor

Question 2

A female patient presents with bilateral buccal reticulate white streaks. The pain increases upon intake of spicy food. The patient denies any history of tobacco use but has amalgam fillings on her third molars. What is the most likely diagnosis?

Accepted Answer

Lichen planus

Answer

Leukoplakia

Answer

Aphthous stomatitis

Answer

Candidiasis

Question 3

Which diagnostic procedure involves applying pressure to a suspected lesion to visualize the evacuation of its coloration?

Accepted Answer

Diascopy

Answer

Fluoroscopy

Answer

Arthroscopy

Answer

Endoscopy

Question 4

Which of the following statements is NOT true about erythema nodosum?

Accepted Answer

Non-tender nodules

Answer

Seen over the anterior aspect of the legs

Answer

More common in females

Answer

Involution occurs in three to six weeks

Question 5

A patient presents with hyperhidrosis and clubbing of the fingers. What is the most likely diagnosis?

Accepted Answer

Pachydermoperiostosis

Answer

Acromegaly

Answer

Rheumatoid arthritis

Answer

Periostitis

Question 6

Phrynoderma is due to deficiency of which nutrient?

Accepted Answer

Essential fatty acids

Answer

Vitamin D

Answer

Niacin

Answer

Vitamin A

Question 7

Erythema nodosum is not seen in which of the following conditions?

Accepted Answer

Giant cell arteritis

Answer

Primary Tuberculosis

Answer

Sulfonamides

Answer

Streptococcal infection

Question 8

Which of the following conditions does NOT exhibit Koebner phenomenon?

Accepted Answer

Vitiligo

Answer

Lichen planus

Answer

Warts

Answer

Psoriasis

Question 9

A 20-year-old female presents with itchy, violaceous, shiny, flat-topped, polygonal papules on the flexor surface of the wrist. Examination under a magnifying lens reveals fine streaks on the lesion surface, enhanced by mineral oil. Koebner's phenomenon is present. Oral mucosa shows some lesions, including erosive lesions on the tongue. Nails exhibit thinning, distal splitting, longitudinal ridging, and pterygium. What is the most likely diagnosis?

Accepted Answer

Lichen planus

Answer

Lichenoid eruption

Answer

Lichen nitidus

Answer

Discoid lupus erythematosus

Question 10

Migratory necrolytic erythema is seen in all conditions, except:

Accepted Answer

Hepatitis C

Answer

Hepatitis B

Answer

Short bowel syndrome

Answer

Myeloproliferative disorders

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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