Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 351: Phrynoderma is primarily associated with a deficiency of which of the following?

A. Essential fatty acid
B. Vitamin A (Correct Answer)
C. Vitamin D
D. Niacin

Explanation: ***Vitamin A*** - **Phrynoderma** (toad skin) has been **classically attributed to vitamin A deficiency** in traditional medical literature and was the accepted answer in historical examinations. - It presents as **follicular hyperkeratosis** with dry, scaly, rough skin having prominent hair follicles with a sandpaper-like texture. - However, **modern evidence** suggests phrynoderma is a **multifactorial condition** often involving **multiple nutritional deficiencies**, with vitamin A being one important contributor among others. *Essential fatty acid* - Deficiency of **essential fatty acids** (linoleic and alpha-linolenic acid) causes **skin dryness, flakiness, and follicular hyperkeratosis**. - **Recent studies** indicate EFA deficiency may play a **significant role** in phrynoderma, particularly in developing countries where multiple nutritional deficiencies coexist. - The clinical presentation can closely mimic vitamin A deficiency-related skin changes. *Vitamin D* - Deficiency of **vitamin D** primarily causes **rickets** in children and **osteomalacia** in adults with bone pain, muscle weakness, and skeletal deformities. - While vitamin D has roles in skin health, its deficiency does not directly cause the follicular hyperkeratosis characteristic of phrynoderma. *Niacin* - **Niacin (vitamin B3)** deficiency causes **pellagra** with the classic \"3 Ds\": **dermatitis, diarrhea, and dementia**. - Pellagra dermatitis is typically **symmetrical in sun-exposed areas** with redness, scaling, and hyperpigmentation—distinctly different from the follicular pattern of phrynoderma.

Question 352: Itchy purple papule followed by hyperpigmentation on resolution, is seen in?

A. Addison's disease
B. DM
C. Hypothyroidism
D. Lichen planus (Correct Answer)

Explanation: ***Correct: Lichen planus*** - This condition presents with characteristic **pruritic (itchy) violaceous (purple) papules** that often develop **post-inflammatory hyperpigmentation** upon resolution. - The classic presentation follows the **"5 P's": Purple, Pruritic, Polygonal, Planar, Papules**. - Lesions commonly affect the **wrists, ankles, lower back, and genitals**, and may also involve the **oral mucosa** (Wickham's striae). - The hyperpigmentation on resolution is due to **melanin incontinence** and dermal melanophages. *Incorrect: Addison's disease* - Characterized by **hyperpigmentation**, but this is typically diffuse, affecting sun-exposed areas, pressure points, and mucous membranes (e.g., gum line), not discrete papules. - The pigmentation is due to increased **ACTH stimulating melanocytes**, without an initial itchy papular stage. *Incorrect: DM (Diabetes Mellitus)* - Diabetes Mellitus can cause various skin manifestations, including **acanthosis nigricans**, necrobiosis lipoidica diabeticorum, and diabetic dermopathy. - These manifestations do not typically present as itchy purple papules followed by hyperpigmentation, but rather as thickened, velvety skin folds or atrophic, pigmented lesions. *Incorrect: Hypothyroidism* - Can lead to **dry, coarse skin**, and occasionally **non-pitting edema** (myxedema). - It does not present with itchy purple papules or lesions that resolve with hyperpigmentation.

Question 353: Miliaria arises from obstruction of ?

A. Eccrine sweat glands (Correct Answer)
B. Apocrine sweat glands
C. Sebaceous glands
D. Ectopic sebaceous glands

Explanation: ***Eccrine sweat glands*** - Miliaria, commonly known as **prickly heat**, occurs due to the obstruction of the **eccrine sweat ducts**. - This obstruction traps sweat beneath the skin, leading to inflammation and characteristic rash. *Apocrine sweat glands* - **Apocrine glands** are primarily located in the axillae and anogenital region and are associated with body odor, not miliaria. - Obstruction of apocrine glands can lead to conditions like **hidradenitis suppurativa**, which is distinct from miliaria. *Sebaceous glands* - **Sebaceous glands** produce sebum and are responsible for conditions like **acne vulgaris** when their ducts become clogged. - They are not involved in sweat production or the pathology of miliaria. *Ectopic sebaceous glands* - **Ectopic sebaceous glands** are sebaceous glands found in unusual locations, such as Fordyce spots in the mouth or Montgomery glands in the areola. - While they produce sebum, their obstruction is unrelated to the development of miliaria.

Question 354: A child with fever who has multiple erythematous skin lesions and, on microscopic examination, shows neutrophilic and histiocytic infiltration in the dermis is diagnosed with what?

A. Sweet syndrome (Correct Answer)
B. Pyoderma gangrenosum
C. Kawasaki disease
D. Behçet's syndrome

Explanation: ***Sweet syndrome*** - Sweet syndrome (acute febrile neutrophilic dermatosis) is characterized by **fever** and the sudden onset of **erythematous plaques or nodules**. - **Histopathology** reveals diffuse **neutrophilic and histiocytic infiltration** in the dermis without vasculitis, which matches the description. *Behçet's syndrome* - Behçet's syndrome is characterized by recurrent **oral and genital ulcers**, **uveitis**, and skin lesions, but typically does not show widespread erythematous lesions with neutrophilic infiltration as the primary skin manifestation. - The histopathology may show leukocytoclastic vasculitis or neutrophilic infiltration in some cases, but the classic clinical triad distinguishes it from Sweet syndrome. *Pyoderma gangrenosum* - Pyoderma gangrenosum presents as rapidly enlarging, **painful necrotic ulcers** with undermined borders, which differs from the "multiple erythematous skin lesions" described. - While it involves neutrophilic infiltration, the clinical presentation of an ulcer is distinct from the more diffuse erythematous lesions of Sweet syndrome. *Kawasaki disease* - Kawasaki disease is a childhood vasculitis presenting with **fever** and **polymorphous rash**, along with conjunctivitis, oral changes, and extremity changes. - Histopathology shows **vasculitis** with perivascular infiltration, not the diffuse dermal neutrophilic infiltration without vasculitis seen in Sweet syndrome. - The clinical criteria (conjunctivitis, strawberry tongue, cervical lymphadenopathy) help distinguish it.

Question 355: Target or iris lesions are seen in:

A. Erythema multiforme (Correct Answer)
B. Urticaria
C. Scabies
D. Lichen planus

Explanation: ***Erythema multiforme*** - Erythema multiforme is characterized by **target lesions** (also known as iris lesions), which are concentric rings of color resembling a bull's-eye. - These lesions typically have a **dusky center**, a paler edematous ring, and an outer erythematous halo. *Urticaria (hives)* - Urticaria presents with **pruritic, transient wheals** (hives) that are typically erythematous and edematous, but they do not form target or iris patterns. - The lesions in urticaria are often **blanchable** and migrate rapidly. *Scabies (itch mite infestation)* - Scabies manifests as **intensely pruritic papules, vesicles, and burrows**, often found in web spaces of fingers, wrists, and genitalia. - It does not produce target lesions; burrows are a **pathognomonic sign**. *Lichen planus (inflammatory skin condition)* - Lichen planus characteristically presents with **pruritic, polygonal, purple, planar papules and plaques** (the 6 P's). - It may also show **Wickham's striae** (fine white lines on the surface), but it does not form target-like lesions.

Question 356: Which of the following statements about erythema multiforme is false?

A. Lesions are usually asymmetrical. (Correct Answer)
B. Due to sulphonamide
C. Due to Herpes simplex
D. Mucous membrane involvement occurs in EM major

Explanation: ***Lesions are usually asymmetrical.*** - Erythema multiforme characteristically presents with **bilateral and symmetrical lesions**, not asymmetrical ones. - The classic **targetoid lesions** (distinctive bullseye shape) typically appear symmetrically on the extremities and trunk. - This statement is FALSE and is therefore the correct answer to this question. *Due to Herpes simplex* - **Herpes simplex virus (HSV) infection** is the most common infectious cause of erythema multiforme, particularly the recurrent form. - The rash typically appears 1-3 weeks after an HSV outbreak. - This statement is TRUE. *Due to sulphonamide* - **Sulfonamide drugs** are well-known to trigger drug-induced erythema multiforme, as well as more severe forms like Stevens-Johnson syndrome (SJS). - This highlights its association with medications as triggers. - This statement is TRUE. *Mucous membrane involvement occurs in EM major* - **Mucous membrane involvement** is a defining feature of **erythema multiforme major**, affecting the oral cavity, eyes, and genitals. - **EM minor** typically presents with only cutaneous lesions without significant mucosal involvement. - This statement is TRUE.

Question 357: Dyskeratosis refers to which of the following?

A. Abnormal, premature keratinization within cells below the stratum granulosum. (Correct Answer)
B. Discontinuity of the skin showing incomplete loss of epidermis.
C. Keratinization with retained nuclei in the stratum corneum.
D. Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.

Explanation: ***Abnormal, premature keratinization within cells below the stratum granulosum.*** - **Dyskeratosis** is a histological term for **premature keratinization** of individual keratinocytes. - This typically occurs in cells that are *below* the **stratum granulosum**, often in the stratum spinosum, indicating abnormal differentiation. *Discontinuity of the skin showing incomplete loss of epidermis.* - This description refers to an **erosion** or **ulceration**, depending on the depth of the epidermal loss. - It does not specifically describe abnormal cellular keratinization. *Keratinization with retained nuclei in the stratum corneum.* - This is the definition of **parakeratosis**, which is a normal finding in mucous membranes but an abnormal finding in skin, often associated with disorders like **psoriasis**. - It indicates incomplete maturation of keratinocytes as they reach the stratum corneum. *Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.* - This describes **hyperkeratosis**, which is an increase in the thickness of the **stratum corneum**. - While it can involve abnormal keratin, it refers to increased thickness, not premature individual cell keratinization.

Question 358: All of the following regarding lichen planus are true except which of the following?

A. Associated with Hepatitis 'C'
B. Does not involve mucous membrane (Correct Answer)
C. Topical steroids are the mainstay of therapy
D. Spontaneous remission occurs after 6 months to 2 years

Explanation: ***Does not involve mucous membrane*** - **Lichen planus** frequently involves mucous membranes, particularly the **oral mucosa**, where it can present as white reticular striae (Wickham's striae) or erosive lesions. - Mucous membrane involvement is a key diagnostic feature and can be painful, affecting eating and drinking. *Associated with Hepatitis 'C'* - There is a well-established association between **lichen planus** and **Hepatitis C virus** (HCV) infection, particularly in cases of oral lichen planus. - HCV infection can trigger or exacerbate immune-mediated conditions like lichen planus. *Topical steroids are the mainstay of therapy* - **Topical corticosteroids** are indeed the **first-line treatment** for many forms of lichen planus, especially localized cutaneous or oral lesions, to reduce inflammation and symptoms. - For more severe or widespread cases, systemic corticosteroids or other immunomodulators may be used. *Spontaneous remission occurs after 6 months to 2 years* - **Lichen planus** often undergoes **spontaneous remission**, typically within **6 months to 2 years** for cutaneous forms. - However, oral lichen planus tends to be more chronic and persistent.

Question 359: Which "P" describes the characteristic shape of lichen planus lesions?

A. Polyhedral
B. Polygonal (Correct Answer)
C. Plane
D. Pruritus

Explanation: ***Polygonal*** - Lichen planus lesions are classically described as having a **polygonal (angular) shape**, one of the "6 Ps" of lichen planus. - The papules have **distinct, angular borders** that create a geometric, many-sided appearance. - This is a key morphological feature used to identify lichen planus clinically. *Polyhedral* - **Polyhedral** refers to a three-dimensional solid figure with many faces (like a crystal or polyhedron). - This term does not describe the two-dimensional shape of skin lesions. - Not part of the classic "6 Ps" mnemonic. *Plane* - While lichen planus lesions are **planar (flat-topped)**, which IS one of the "6 Ps," this describes the **surface topography**, not the **shape** of the lesions. - "Plane/planar" refers to the flat surface when viewed from the side, whereas "polygonal" describes the angular outline when viewed from above. *Pruritus* - **Pruritic (itchy)** is indeed one of the "6 Ps" of lichen planus and a very common clinical feature. - However, pruritus describes a **symptom**, not the **shape** of the lesions. - The question specifically asks about shape characteristics.

Question 360: Which of the following statements about Pityriasis rosea is true?

A. It is a self-limiting condition. (Correct Answer)
B. It can lead to life-threatening infections.
C. It is caused by dermatophytes.
D. It is a chronic relapsing condition.

Explanation: ***It is a self-limiting condition.*** - **Pityriasis rosea** is characterized by a distinctive rash that typically resolves on its own within **6-8 weeks** without specific treatment. - Most patients experience complete resolution, and **recurrences are uncommon**. - Often preceded by a **herald patch** followed by smaller oval lesions in a **"Christmas tree" distribution** on the trunk. *It can lead to life-threatening infections.* - While the exact etiology is unknown, **Pityriasis rosea** is generally considered **benign** and does not typically lead to systemic complications or life-threatening infections. - The rash itself is a localized skin condition that does not compromise the immune system or predispose to severe secondary infections. *It is caused by dermatophytes.* - **Dermatophytes** are fungi that cause superficial fungal infections such as ringworm (**tinea** infections). - **Pityriasis rosea** is thought to be triggered by certain **viral infections**, particularly **human herpesvirus 6 (HHV-6)** and **HHV-7**, not fungal organisms. - This helps differentiate it from fungal conditions like tinea corporis. *It is a chronic relapsing condition.* - **Pityriasis rosea** is generally an **acute, self-limiting eruption** that resolves spontaneously, making it distinct from chronic, relapsing conditions such as **psoriasis** or **eczema**. - A single episode usually confers long-lasting immunity, and **recurrences are rare** (occurring in <2% of cases).

Practice by Chapter

Structure and Function of Skin

Practice Questions

Cutaneous Histopathology

Practice Questions

Dermatological Examination

Practice Questions

Skin Lesions: Morphology and Description

Practice Questions

Principles of Diagnosis in Dermatology

Practice Questions

Dermatological Procedures

Practice Questions

Wound Healing

Practice Questions

Cutaneous Immunology

Practice Questions

Genetics in Dermatology

Practice Questions

Cutaneous Manifestations of Systemic Diseases

Practice Questions

Geriatric Dermatology

Practice Questions

Pediatric Dermatology Basics

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free