Basic Dermatology Practice Questions

Q: A 26-year-old recently married woman presents with tender nodules on her shin. What is the most important initial history to obtain?

Any new medications she may have started. ### Explanation **Concept:** The clinical presentation of "tender nodules on the shin" is the classic description of **Erythema Nodosum (EN)**. EN is a type IV hypersensitivity reaction (septal panniculitis) occurring in the subcutaneous fat. It is a reactive process triggered by various systemic factors, including infections, drugs, and inflammatory diseases. **Why Option B is Correct:** In a "recently married woman," the most high-yield association to consider is the initiation of **Oral Contraceptive Pills (OCPs)**. OCPs are a leading pharmacological cause of Erythema Nodosum. Before embarking on extensive diagnostic workups for systemic diseases (like Sarcoidosis or TB), a clinician must rule out common triggers like new medications (OCPs, Sulfonamides, Penicillins) or recent infections (Streptococcal pharyngitis). **Why Other Options are Incorrect:** * **A. Stress level:** While stress can exacerbate certain dermatological conditions (like psoriasis or eczema), it is not a recognized trigger for Erythema Nodosum. * **C. History of foreign travel:** While travel might suggest exotic fungal infections (e.g., Coccidioidomycosis) which can cause EN, it is statistically less common than medication-induced EN in a stable, young patient. * **D. Insect bites:** These typically present as papular urticaria or localized cellulitis, not as deep-seated, poorly defined inflammatory nodules on the shins. **NEET-PG High-Yield Pearls:** * **Most common cause overall:** Idiopathic (~50%). * **Most common infectious cause:** Streptococcal pharyngitis (especially in children). * **Classic triad in Sarcoidosis:** Erythema Nodosum + Bilateral Hilar Lymphadenopathy + Arthralgia (**Lofgren’s Syndrome**). * **Key drugs:** OCPs, Sulfonamides, Bromides, and Iodides. * **Clinical feature:** These nodules do **not** ulcerate and heal without scarring, often appearing like a bruise (contusiform).

Q: A 45-year-old patient with a history of elevated cholesterol levels presents with nodular swellings over the tendons. The lesion shown in the image is most likely:

Tendon xanthoma. ***Tendon xanthoma*** - The image displays a **firm, subcutaneous nodule** occurring over a tendon, specifically the Achilles tendon or extensor tendons, which is characteristic of tendon xanthomas. - These are typically associated with **hypercholesterolemia**, particularly familial hypercholesterolemia, and are composed of lipid-laden macrophages (foam cells). *Xanthelasma* - Xanthelasma are **yellowish plaques** that typically appear on or around the eyelids, not on tendons. - While also composed of lipid deposits, their location and flatter morphology differentiate them from the lesion shown. *Tuberous xanthoma* - Tuberous xanthomas are **firm, painless nodules** that often occur over pressure points such as knees, elbows, and buttocks, but they are typically located in the dermis or subcutaneous tissue, not specifically within tendons. - They are often larger and more diverse in shape than the well-defined, tendon-associated lesion seen in the image. *Eruptive xanthoma* - Eruptive xanthomas are **small, yellowish-orange papules** with an erythematous base that appear suddenly in crops, primarily on the extensor surfaces of limbs and buttocks. - They are typically associated with very high triglyceride levels and have a distinct, more widespread, and smaller appearance compared to the single, large tendon-associated nodule.

Q: The following findings on Tzanck smear can be seen in:

All of the above. ***All of the above*** - The image displays multiple **acantholytic cells** (keratinocytes that have lost intercellular connections) with prominent nuclei, which are characteristic findings in several dermatological conditions. - A **Tzanck smear** is a rapid cytological test performed by scraping the base of a fresh blister, staining with Giemsa or Wright stain, and examining under microscopy. **Why all three conditions show similar findings:** *Herpes simplex* - Tzanck smear shows **multinucleated giant cells** with molding of nuclei and **balloon degeneration** of keratinocytes - Acantholytic cells are present due to viral cytopathic effect causing cell separation - These findings are **identical** to those seen in Herpes zoster *Herpes zoster* - Cannot be distinguished from Herpes simplex on Tzanck smear morphology alone - Shows the same **multinucleated giant cells** and **acantholytic keratinocytes** - Viral culture, PCR, or direct fluorescent antibody (DFA) testing needed for definitive differentiation *Paraneoplastic pemphigus* - Shows **acantholytic cells** (rounded keratinocytes with hyperchromatic nuclei) due to autoantibody-mediated destruction of intercellular adhesion - Unlike herpes infections, typically shows acantholytic cells **without** multinucleated giant cells - Definitive diagnosis requires direct immunofluorescence (DIF) on skin biopsy showing intercellular and basement membrane zone IgG/C3 deposition **Note**: While Tzanck smear can show acantholytic cells in all three conditions, the **pattern differs** - herpes shows multinucleated giant cells prominently, while pemphigus shows isolated acantholytic cells. Clinical correlation and confirmatory tests are essential for accurate diagnosis.

Q: The first line treatment for this condition is:

Injection of triamcinolone. ***Injection of triamcinolone*** - The image shows a **keloid**, which is an elevated scar that extends beyond the original wound boundaries. Intralesional injections of **corticosteroids** like triamcinolone are considered a first-line treatment for keloids, reducing inflammation and fibroblast proliferation. - This treatment aims to flatten the keloid, relieve symptoms like itching and pain, and prevent recurrence. *Wide excision and grafting* - **Wide excision** of keloids often leads to **recurrence** that is usually larger than the original keloid, making it an unsuitable primary treatment unless combined with other therapies like radiation or intralesional injections. - **Skin grafting** is generally reserved for very large defects after excision and doesn't prevent recurrence of the keloid itself. *Silicon gel sheeting* - **Silicone gel sheeting** or topical silicone is a commonly used non-invasive treatment for scars, particularly **hypertrophic scars** and smaller keloids. - While effective in some cases for preventing and managing scars, it is generally considered a second-line or adjunctive therapy for established keloids, less effective than intralesional corticosteroids for reducing their size. *No intervention* - **Keloids** are **dermatological conditions** that can cause cosmetic disfigurement, itching, pain, and discomfort. - **No intervention** would mean that the keloid would likely persist or even continue to grow, leading to ongoing symptoms and aesthetic concerns.

Q: A 20-year-old male with no history of any sexual contact presents with following lesions on his penis. What is the diagnosis?

Lichen nitidus. ***Lichen nitidus*** - The image shows numerous small, shiny, **pin-head sized papules** on the penis, which are characteristic of lichen nitidus. - This condition is often **asymptomatic** and benign, and it can occur on the penis without any sexual contact history. *Lichenoides keratosis* - This term is broad and often refers to a benign **inflammatory process** with lichenoid features affecting keratinocytes, usually solitary and often in older adults; it does not typically present as widespread, uniform papules on the penis. - Lichenoides keratosis is often a more **solitary lesion** or a reaction pattern, not a diffuse eruption of small papules like those pictured. *Epstein pearls* - **Epstein pearls** are small, white or yellow cysts found in the mouths of newborns, specifically on the gums or palate, and are remnants of epithelial tissue. - They are a normal finding in neonates and are **not found on the penis** or in a 20-year-old male. *Molluscum contagiosum* - Molluscum contagiosum lesions typically present as **dome-shaped, flesh-colored papules with central umbilication**. - While they can appear on the penis and are sexually transmitted, the lesions in the image lack the characteristic **umbilication** of molluscum contagiosum.

Q: A 41-year-old male complains of itching on the upper chest for one month. What is the most likely diagnosis?

Pityriasis rosea. ***Pityriasis rosea*** - This condition often starts with a **herald patch**, followed by a widespread rash of smaller, oval, pinkish-brown patches, often on the trunk, back, and upper extremities. - The lesions classically align along skin cleavage lines forming a **Christmas tree pattern**, and are frequently associated with pruritus (itching). *Dermatitis herpetiformis* - Characterized by intensely pruritic, **grouped vesicles and papules**, most commonly symmetrical on extensor surfaces like elbows, knees, and buttocks. This presentation is not typical of the provided image. - It is strongly associated with **celiac disease** and is usually seen in younger individuals. *Erythema marginatum* - This is a rare, transient, and **non-pruritic rash** characterized by rapidly enlarging, ring-shaped lesions with a raised, red border and clear center. - It's a key diagnostic criterion for **acute rheumatic fever** and does not typically present with the widespread itchy lesions seen in the image. *Dermatomyositis* - This is an inflammatory myopathy presenting with characteristic skin rashes such as **Gottron's papules** (over knuckles), a heliotrope rash (periorbital edema with a violaceous discoloration), and photosensitivity. - While it can cause itching, the primary skin lesions are distinct from those seen in the image and it is usually accompanied by **muscle weakness**.

Q: Identify the lesion:

Erythema multiforme. ***Erythema multiforme*** - The image displays characteristic **“target lesions”** with concentric rings of redness and sometimes a central blister, which are hallmarks of erythema multiforme. - This condition is an acute, self-limiting inflammatory skin reaction, often triggered by infections (especially **HSV**) or medications. *Psoriasis* - Psoriasis typically presents as well-demarcated, **erythematous plaques** covered with **silvery scales**, which are not seen here. - Lesions frequently occur on extensor surfaces (elbows, knees) and the scalp. *Dermatitis herpetiformis* - Characterized by intensely **pruritic (itchy) vesicles and bullae** (blisters) that often appear in a symmetrical distribution. - It is strongly associated with **celiac disease** and typically affects the extensor surfaces and buttocks. *Erythema marginatum* - Consists of **migratory, macular, non-pruritic, erythematous lesions with central clearing** and serpiginous (wavy) borders. - It is a rare manifestation of **acute rheumatic fever** and does not typically show the concentric rings or blister formation seen in the image.

Q: A 16-year-old boy with cryptorchidism presents with dry skin. Identify the lesion:

X-linked ichthyosis. ***X-linked ichthyosis*** - This condition is characterized by **dry, scaly skin**, particularly prominent on the trunk and extremities, often appearing in male infants and worsening with age. - The association with **cryptorchidism** (undescended testes) is a key diagnostic clue for X-linked ichthyosis, as both conditions are linked to deficiencies in the **steroid sulfatase gene**. *Ichthyosis vulgaris* - This is the most common form of ichthyosis, presenting with **fine, powdery scales**, typically sparing the flexural folds. - It does **not typically present with cryptorchidism** and scales are usually less severe than seen in the image. *Lamellar ichthyosis* - Characterized by **large, dark, plate-like scales** covering the entire body, often accompanied by ectropion (eversion of the eyelids) and palmoplantar hyperkeratosis. - This more severe form is usually evident at birth (collodion baby) and is not generally associated with cryptorchidism. *Kindler syndrome* - A rare genodermatosis characterized by **blistering, photosensitivity, poikiloderma**, and progressive skin fragility. - While it involves skin abnormalities, its clinical presentation with **bullae** and **skin atrophy** is distinct from the dry, scaly skin and cryptorchidism seen in the patient.

Q: Identify the lesion: (Recent NEET Pattern 2016-17)

Erythema multiforme. ***Erythema multiforme*** - The image displays characteristic **targetoid lesions** with multiple concentric rings of color (erythema, edema, pallor), typical of **erythema multiforme**. - These lesions often appear suddenly, symmetrically, and commonly on the extremities, often triggered by infections (e.g., **herpes simplex virus**) or medications. *Gianotti-Crosti syndrome* - Characterized by **monomorphic, flesh-colored to erythematous papules** and papulovesicles, often on the cheeks, buttocks, and extensor surfaces of the limbs. - This condition is typically observed in **children** after viral infections and does not usually present with target lesions. *Pityriasis rosea* - Starts with a single **"herald patch,"** followed by smaller, oval, pinkish-red patches with fine scales, often arranged in a **"Christmas tree pattern"** on the trunk. - The morphology of the lesions in the image, specifically the targetoid appearance, is not consistent with pityriasis rosea. *Acne rosacea* - Marked by **facial erythema**, papules, pustules, and telangiectasias, primarily affecting the central face. - It does not present with the widespread, distinct target lesions seen in the image.

Q: Identify the lesion: (Recent NEET Pattern 2016-17)

Lichen nitidus. ***Lichen nitidus*** - The image displays multiple **tiny, flesh-colored, shiny papules**, which are characteristic of lichen nitidus, often appearing in clusters. - These lesions are typically asymptomatic or mildly pruritic, and commonly found on the trunk, upper extremities, and genitalia. *Lichen planus* - Characterized by **purplish, polygonal, planar, pruritic papules and plaques** (the "6 P's"), often with fine white lines (Wickham's striae). - The lesions in the image do not exhibit the typical purplish hue, distinct polygonal shape, or surface striae of lichen planus. *Atopic dermatitis* - Presents with **erythematous, intensely itchy plaques** that are often excoriated, lichenified, or crusted. - While it can involve various body sites, the discrete, shiny, flesh-colored papules seen here are not typical for atopic dermatitis. *Pompholyx* - Also known as dyshidrotic eczema, this condition is characterized by **small, deep-seated, clear vesicles and bullae** on the palms, soles, and sides of the fingers and toes. - The image does not show vesicular or bullous lesions, nor are the papules consistent with the presentation of pompholyx.

Question 1

A 26-year-old recently married woman presents with tender nodules on her shin. What is the most important initial history to obtain?

Accepted Answer

Any new medications she may have started

Answer

Her stress level

Answer

History of foreign travel

Answer

Insect bites to the legs

Question 2

A 45-year-old patient with a history of elevated cholesterol levels presents with nodular swellings over the tendons. The lesion shown in the image is most likely:

Accepted Answer

Tendon xanthoma

Answer

Xanthelasma

Answer

Tuberous xanthoma

Answer

Eruptive xanthoma

Question 3

The following findings on Tzanck smear can be seen in:

Accepted Answer

All of the above

Answer

Herpes simplex

Answer

Herpes zoster

Answer

Paraneoplastic pemphigus

Question 4

The first line treatment for this condition is:

Accepted Answer

Injection of triamcinolone

Answer

Wide excision and grafting

Answer

Silicone gel sheeting

Answer

No intervention

Question 5

A 20-year-old male with no history of any sexual contact presents with following lesions on his penis. What is the diagnosis?

Accepted Answer

Lichen nitidus

Answer

Lichenoides keratosis

Answer

Epstein pearls

Answer

Molluscum contagiosum

Question 6

A 41-year-old male complains of itching on the upper chest for one month. What is the most likely diagnosis?

Accepted Answer

Pityriasis rosea

Answer

Dermatitis herpetiformis

Answer

Erythema marginatum

Answer

Dermatomyositis

Question 7

Identify the lesion:

Accepted Answer

Erythema multiforme

Answer

Psoriasis

Answer

Dermatitis herpetiformis

Answer

Erythema marginatum

Question 8

A 16-year-old boy with cryptorchidism presents with dry skin. Identify the lesion:

Accepted Answer

X-linked ichthyosis

Answer

Ichthyosis vulgaris

Answer

Lamellar ichthyosis

Answer

Kindler syndrome

Question 9

Identify the lesion: (Recent NEET Pattern 2016-17)

Accepted Answer

Erythema multiforme

Answer

Gianotti-Crosti syndrome

Answer

Pityriasis rosea

Answer

Acne rosacea

Question 10

Identify the lesion: (Recent NEET Pattern 2016-17)

Accepted Answer

Lichen nitidus

Answer

Lichen planus

Answer

Atopic dermatitis

Answer

Pompholyx

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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