Basic Dermatology Practice Questions

Q: Most efficient antigen-presenting cell in the skin is?

Langerhans cell. ***Langerhans cell*** - **Langerhans cells** are specialized dendritic cells found in the **epidermis** and are the primary professional antigen-presenting cells (APCs) of the skin. - They are highly efficient at capturing and processing antigens, then migrating to regional **lymph nodes** to activate T lymphocytes. *Dendritic cell* - While Langerhans cells are a type of **dendritic cell**, the term "dendritic cell" is broader and includes various populations found in different tissues. - In the context of the skin, the specific and most efficient type of dendritic cell is the Langerhans cell. *Macrophages* - **Macrophages** are phagocytic cells that can present antigens, but they are generally less efficient at initiating primary T-cell responses compared to professional APCs like Langerhans cells. - They are found in the dermis but play a secondary role in initiating skin-specific immune responses compared to Langerhans cells. *Kupffer cells* - **Kupffer cells** are specialized macrophages found in the **liver sinusoids**. - They are primarily involved in filtering blood and presenting antigens within the liver, not in the skin.

Q: The Tzanck test is positive in the following conditions, except:

EBV. ***EBV*** - The **Tzanck test** is used to detect **multinucleated giant cells** and **acantholytic cells**, which are characteristic cytopathic effects of **herpes group viruses** on epithelial cells. - **Epstein-Barr Virus (EBV)** is a herpesvirus that causes infectious mononucleosis and is associated with various cancers, but it does not typically cause mucocutaneous lesions with the classic cytopathic changes detectable by a Tzanck test. *Herpes Zoster* - **Herpes Zoster**, caused by the **varicella-zoster virus (VZV)**, is a herpesvirus that causes **shingles** and produces characteristic **vesicular lesions** in a dermatomal distribution. - The **Tzanck test** will be positive in herpes zoster due to the presence of **multinucleated giant cells** and **acantholytic cells** in the vesicular fluid or scrapings. *Herpes Simplex* - **Herpes Simplex Virus (HSV)** causes **cold sores**, **genital herpes**, and other mucocutaneous lesions characterized by **vesicles** and **ulcers**. - A positive **Tzanck test** in HSV infections reveals **multinucleated giant cells** and **intranuclear inclusions**, confirming viral cytopathic effects. *Varicella* - **Varicella**, also known as **chickenpox**, is caused by the **varicella-zoster virus (VZV)** and manifests as widespread **vesicular rash**. - The **Tzanck test** is positive in varicella infections, showing the presence of **multinucleated giant cells** and **acantholysis** within the vesicular lesions.

Q: Which of the following is not classified as a primary cutaneous disorder?

Reiter's disease. ***Reiter's disease*** - **Reiter's disease**, now known as **Reactive Arthritis**, is characterized by a triad of arthritis, urethritis, and conjunctivitis, often triggered by a preceding infection. - While it can involve mucocutaneous lesions (e.g., **circinate balanitis**, **keratoderma blennorrhagicum**), these are secondary manifestations of a systemic inflammatory process rather than a primary disorder originating in the skin itself. *Lichen planus* - **Lichen planus** is a chronic inflammatory disorder that primarily affects the skin, hair, nails, and mucous membranes. - It presents with characteristic **"6 P's"** (pruritic, purple, polygonal, planar papules and plaques), making it a primary cutaneous condition. *Ichthyosis* - **Ichthyosis** refers to a group of genetic skin disorders characterized by abnormally dry, thickened, and scaly skin due to defects in skin barrier function and keratinization. - These are directly classified as primary disorders of the skin's structure and function. *Psoriasis* - **Psoriasis** is a chronic autoimmune disease that primarily affects the skin, leading to rapid skin cell turnover. - It manifests as well-demarcated, erythematous plaques with silvery scales, making it a classic example of a primary cutaneous disorder.

Q: Eosinophilic pustular folliculitis is a rare form of folliculitis that is seen with increased frequency in patients with what?

HIV infection. ***HIV infection*** - Eosinophilic pustular folliculitis, also known as **Ofuji's disease**, is a pruritic skin condition commonly seen in patients with **advanced HIV disease**. - Its exact pathogenesis is unknown, but it is thought to be an immune dysregulation phenomenon related to the **CD4 count decline** seen in HIV. - The condition presents as recurrent crops of sterile, pruritic follicular papules and pustules, particularly on the face, trunk, and extremities. *ABPA* - **Allergic bronchopulmonary aspergillosis (ABPA)** is a hypersensitivity reaction to *Aspergillus* species, primarily affecting the lungs. - It is characterized by **eosinophilia**, but it does not cause eosinophilic pustular folliculitis. - ABPA is associated with asthma and cystic fibrosis. *Asthma* - **Asthma** is a chronic inflammatory disease of the airways, characterized by **bronchial hyperresponsiveness** and reversible airflow obstruction. - While asthma can involve eosinophilic inflammation of the airways, it is not directly associated with eosinophilic pustular folliculitis. *Leukemia cutis* - **Leukemia cutis** refers to the infiltration of the skin by leukemic cells, often presenting as nodules, plaques, or papules. - This condition is a direct manifestation of leukemia and is biologically distinct from eosinophilic pustular folliculitis.

Q: Which of the following conditions does not demonstrate the Koebner phenomenon?

Lichen sclerosus. ***Lichen sclerosus*** - This condition is characterized by **white, atrophic plaques**, primarily affecting the anogenital region, and **typically does not exhibit the Koebner phenomenon** or does so only rarely. - While isolated case reports exist, lichen sclerosus is **not classically considered a Koebnerizing disorder** in standard medical teaching. - The pathogenesis involves **autoimmune processes, genetic factors, and local tissue changes**, rather than a consistent direct response to trauma like the classic Koebnerizing disorders. *Lichen planus* - **Lichen planus** is a **classic example** of the **Koebner phenomenon**, where new violaceous papules develop along lines of trauma or scratching. - This isomorphic response to trauma is a **characteristic diagnostic feature**. - Linear arrangement of lesions following trauma is commonly observed. *Vitiligo* - **Vitiligo** is a **well-recognized Koebnerizing disorder**, with new **depigmented patches** appearing at sites of skin injury, friction, or trauma. - The Koebner phenomenon is reported in **20-60% of vitiligo patients** and is an important mechanism for disease spread. - Common sites include areas of belt pressure, watchbands, and surgical scars. *Psoriasis* - **Psoriasis** is the **most classic example** of the Koebner phenomenon, with new **psoriatic plaques** emerging at sites of trauma, surgery, or even sunburn. - First described by Heinrich Koebner in 1876 in a psoriasis patient. - Occurs in approximately **25-50% of psoriasis patients** and is a key diagnostic clue.

Q: Itchy, polygonal, violaceous papules are seen in

Lichen planus. ***Lichen planus*** - This condition is clinically characterized by the "6 P's": **pruritic**, **polygonal**, **planar**, **purple**, **papules**, and **plaques**. The description fits perfectly. - Microscopic findings often include a **saw-tooth rete ridge pattern** and a dense lymphocytic infiltrate at the dermoepidermal junction. *Psoriasis* - Characterized by **well-demarcated erythematous plaques** with **silvery scales**, often found on extensor surfaces. - Histologically, it shows **acanthosis** with elongated rete ridges, parakeratosis, and neutrophilic infiltrates (Munro microabscesses). *Pemphigus* - An autoimmune blistering disease characterized by **flaccid bullae** and erosions, often affecting the skin and mucous membranes. - Caused by autoantibodies against **desmogleins**, leading to intraepidermal blistering (acantholysis). *Pityriasis rosea* - Presents with a **herald patch** followed by smaller, oval-shaped, pinkish-red lesions with fine scales, typically in a "Christmas tree" pattern on the trunk. - It is often associated with a preceding viral infection and is generally **self-resolving**.

Q: In which of the following conditions is Koebner phenomenon NOT seen?

Lichen simplex chronicus. ***Lichen simplex chronicus*** - The **Koebner phenomenon**, or isomorphic response, is the appearance of new skin lesions at sites of trauma; it is **not seen** in lichen simplex chronicus. - Lichen simplex chronicus is characterized by thickened, leathery skin resulting from **chronic scratching or rubbing**, representing a reactive change rather than an isomorphic response to injury. - This is purely a **reactive hyperplasia** due to chronic trauma, not an inflammatory dermatosis with isomorphic response. *Lichen planus* - **Koebner phenomenon is classically positive** in lichen planus, where new papules can erupt along lines of trauma or scratching. - This is one of the **well-established conditions** showing true isomorphic response, highlighting the underlying **inflammatory nature** of the disease. *Lichen sclerosus* - The Koebner phenomenon can be observed in lichen sclerosus, where new lesions may appear in areas subjected to **friction or minor trauma**. - While debated, this contributes to the spread and persistence of the disease, particularly in affected mucocutaneous areas. *Erythema multiforme* - Koebner phenomenon is **not classically seen** in erythema multiforme, as it is an **acute hypersensitivity reaction** rather than a chronic inflammatory dermatosis. - The target lesions develop due to the underlying **immune reaction** (often triggered by HSV or drugs), not from trauma-induced isomorphic response. - However, among the options, **lichen simplex chronicus** is the most definitive answer as a condition resulting purely from chronic mechanical trauma without isomorphic response.

Q: Atrophic cigarette paper scars in the skin are classically seen in which condition?

Ehlers-Danlos syndrome. ***Ehlers-Danlos syndrome*** - **Atrophic cigarette paper scars** are a classic dermatological feature due to abnormal collagen synthesis, leading to fragile skin that heals poorly. - The skin in Ehlers-Danlos syndrome is often **hyperextensible** and velvety, contributing to the characteristic scarring after even minor trauma. *Osteogenesis imperfecta* - This condition primarily affects **bone formation**, leading to recurrent fractures and **blue sclera**. - While it involves collagen defects (Type I), it does not classically present with atrophic cigarette paper scars. *Chondrodysplasia* - This is a group of genetic disorders that specifically impact **cartilage and bone development**, leading to skeletal deformities. - It does not present with characteristic skin findings like atrophic scarring. *Marfan syndrome* - This genetic disorder primarily affects **connective tissue**, leading to issues in the cardiovascular system (e.g., **aortic dissection**), eyes (e.g., **lens dislocation**), and skeletal system (e.g., **arachnodactyly**). - While it affects connective tissue, **atrophic cigarette paper scars** are not a typical skin manifestation of Marfan syndrome.

Question 1

Most efficient antigen-presenting cell in the skin is?

Accepted Answer

Langerhans cell

Answer

Dendritic cell

Answer

Macrophages

Answer

Kupffer cells

Question 2

The Tzanck test is positive in the following conditions, except:

Accepted Answer

EBV

Answer

Herpes Simplex

Answer

Varicella

Answer

Herpes Zoster

Question 3

Which of the following is not classified as a primary cutaneous disorder?

Accepted Answer

Reiter's disease

Answer

Lichen planus

Answer

Ichthyosis

Answer

Psoriasis

Question 4

Eosinophilic pustular folliculitis is a rare form of folliculitis that is seen with increased frequency in patients with what?

Accepted Answer

HIV infection

Answer

ABPA

Answer

Asthma

Answer

Leukemia cutis

Question 5

Which of the following conditions does not demonstrate the Koebner phenomenon?

Accepted Answer

Lichen sclerosus

Answer

Lichen planus

Answer

Vitiligo

Answer

Psoriasis

Question 6

Itchy, polygonal, violaceous papules are seen in

Accepted Answer

Lichen planus

Answer

Psoriasis

Answer

Pemphigus

Answer

Pityriasis rosea

Question 7

In which of the following conditions is Koebner phenomenon NOT seen?

Accepted Answer

Lichen simplex chronicus

Answer

Lichen planus

Answer

Erythema multiforme

Answer

Lichen sclerosus

Question 8

Atrophic cigarette paper scars in the skin are classically seen in which condition?

Accepted Answer

Ehlers-Danlos syndrome

Answer

Osteogenesis imperfecta

Answer

Chondrodysplasia

Answer

Marfan syndrome

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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