Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 281: A skin condition unique to Chronic Kidney Disease patients:

A. Scleromyxedema
B. Calcinosis cutis
C. Nephrogenic fibrosing dermopathy (Correct Answer)
D. Norwegian scabies

Explanation: ***Nephrogenic fibrosing dermopathy*** - Also known as **Nephrogenic Systemic Fibrosis (NSF)**, this condition is **exclusively seen in patients with renal insufficiency**, particularly those exposed to gadolinium-based contrast agents - Presents with **painful, woody induration and thickening of the skin**, often accompanied by joint contractures - This is the **only skin condition uniquely associated with chronic kidney disease** *Scleromyxedema* - A rare chronic skin disease characterized by **generalized papular and sclerodermoid skin lesions**, often associated with **monoclonal gammopathy** - **Not uniquely associated with renal disease**, although it may rarely occur in patients with kidney dysfunction *Calcinosis cutis* - Involves **deposition of calcium salts in the skin and subcutaneous tissues** - Can occur in various conditions causing hypercalcemia or tissue damage - While seen in patients with **end-stage renal disease** due to mineral and bone disorders, it is **not exclusive** to CKD (also occurs in CREST syndrome, dermatomyositis, hyperparathyroidism) *Norwegian scabies* - Also known as **crusted scabies**, a severe form characterized by widespread **hyperkeratotic crusts** and massive mite infestation - Primarily affects **immunocompromised individuals**, elderly, or those with neurological impairments - **Not specific to chronic kidney disease**

Question 282: Which of the following is true about keratinocytes?

A. Differentiate in basal layer
B. Ectoderm derived cell (Correct Answer)
C. Mature in basal layer
D. Present only in basal layer

Explanation: ***Ectoderm derived cell*** - Keratinocytes originate from the **ectoderm**, one of the three primary germ layers in embryonic development, which gives rise to the epidermis. - This ectodermal origin is fundamental to their role in forming the protective outer layer of the skin. *Differentiate in basal layer* - Keratinocytes in the **basal layer (stratum basale)** are primarily responsible for **proliferation** (cell division) rather than differentiation. - **Differentiation** into flattened, keratin-filled cells occurs as they migrate upwards through the epidermal layers. *Mature in basal layer* - Maturation, which involves the accumulation of **keratin** and the loss of organelles, primarily occurs in the **upper layers** of the epidermis (stratum spinosum, granulosum, corneum). - The basal layer is where new cells are generated, not where they reach their mature, fully keratinized state. *Present only in basal layer* - While keratinocytes originate in the basal layer, they are the **predominant cell type throughout all layers of the epidermis**. - They represent approximately 90% of epidermal cells and are found from the stratum basale to the stratum corneum.

Question 283: An 85-year-old male cigar smoker with no notable medical history presented with black discoloration and hairy appearance of the tongue, which had lasted several years. He said he did not use bismuth-containing compounds. This condition could be treated with all of the following except:

A. Discontinuing smoking
B. Applying topical retinoids
C. Topical antibiotics (Correct Answer)
D. Application of 40 percent urea

Explanation: ***Topical antibiotics*** - The presented condition, **hairy black tongue (lingua villosa nigra)**, is often a benign condition caused by **hypertrophy of the filiform papillae** and is generally not related to bacterial infection. - While bacteria and fungi can contribute to the discoloration, **topical antibiotics** are not a primary treatment and would be ineffective against the underlying papillary hypertrophy. *Discontinuing smoking* - **Smoking** is a well-known risk factor for **hairy black tongue** as it can promote the accumulation of keratin on the filiform papillae. - Quitting smoking can help resolve the condition by reducing the irritants that contribute to its development. *Applying topical retinoids* - **Topical retinoids** can aid in the **exfoliation of keratinized cells** and promote normal epithelial differentiation. - This can help reduce the hyperkeratosis of the filiform papillae associated with **hairy black tongue**. *Application of 40 percent urea* - **Urea** is a **keratolytic agent** that can help soften and loosen the thickened keratinized layer on the tongue. - Application of **40% urea** can facilitate the removal of the elongated filiform papillae and the trapped debris, improving the appearance of hairy black tongue.

Question 284: Which of the following is true about Dyskeratosis congenita?

A. Nail dystrophy (Correct Answer)
B. Hyperkeratosis
C. Leukoplakia
D. Pancytopenia

Explanation: ***Nail dystrophy*** - **Nail dystrophy** (thin, brittle, ridged, or absent nails) is one of the **classic mucocutaneous triad** of Dyskeratosis congenita. - It is a **key diagnostic feature**, often presenting early in childhood and seen in nearly all patients. - This is the **MOST characteristic** clinical feature among the options listed. *Hyperkeratosis* - Generalized **hyperkeratosis is NOT a characteristic feature** of Dyskeratosis congenita. - The typical skin changes are **reticulated hyperpigmentation** (lacy pigmentation on neck and chest), not hyperkeratosis. - This is the clearly **incorrect option**. *Leukoplakia* - **Oral leukoplakia** is indeed a true feature and part of the classic mucocutaneous triad. - However, it may appear later than nail changes and is not always present in early disease. - While true, **nail dystrophy is more consistently present** and remains the best single answer. *Pancytopenia* - **Bone marrow failure with pancytopenia** is a major complication occurring in 80-90% of patients. - However, it typically develops **later in life** (teens to early adulthood), whereas nail dystrophy presents earlier. - As a systemic complication rather than a direct mucocutaneous manifestation, nail dystrophy remains the more characteristic diagnostic feature for clinical identification.

Question 285: Wood's lamp is used in the diagnosis of:

A. P. versicolor
B. Vitiligo
C. Porphyria
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - Wood's lamp is a diagnostic tool that uses **ultraviolet light (UV-A at 365 nm)** to detect certain skin conditions by observing characteristic fluorescence patterns. - All three conditions listed show distinctive features under Wood's lamp examination, making this an important diagnostic tool in dermatology. **P. versicolor (Pityriasis versicolor)** - Shows characteristic **yellow-green to golden-orange fluorescence** under Wood's lamp - This fluorescence is due to metabolites produced by *Malassezia* yeast species - Helps confirm diagnosis and delineate the extent of lesions, especially on darker skin **Vitiligo** - Depigmented areas appear as **bright, stark white patches** with sharp borders under UV light - Wood's lamp accentuates areas of **complete melanin loss**, making subtle lesions more visible - Particularly useful for detecting vitiligo on fair skin where lesions may not be clinically apparent - Helps differentiate vitiligo from other hypopigmented conditions **Porphyria** - In **porphyria cutanea tarda (PCT)** and **congenital erythropoietic porphyria (CEP)**, Wood's lamp detects **coral-red to pink-orange fluorescence** - Fluorescence is seen in urine (containing porphyrins), teeth, and sometimes skin lesions - This occurs due to accumulation of **porphyrins**, which are photosensitive compounds that fluoresce under UV light - Useful screening tool for suspected porphyria cases

Question 286: Miliaria is a disorder of-

A. Holocrine glands
B. Sebaceous glands
C. Eccrine glands (Correct Answer)
D. Apocrine glands

Explanation: ***Eccrine glands*** - **Miliaria**, commonly known as prickly heat or heat rash, is a skin condition that results from the obstruction of the **eccrine sweat ducts**. - This obstruction leads to the leakage of sweat into the epidermis or dermis, causing inflammatory reactions and characteristic lesions. *Holocrine glands* - **Holocrine glands** secrete their entire cell contents, including disintegrated cells, as part of their secretory product. - The **sebaceous glands** are an example of holocrine glands, and their dysfunction is not the primary cause of miliaria. *Sebaceous glands* - **Sebaceous glands** produce **sebum**, an oily substance that lubricates the skin and hair. - Disorders of sebaceous glands include **acne**, not miliaria, which is related to sweat production. *Apocrine glands* - **Apocrine glands** are a type of sweat gland found in specific areas like the axilla and anogenital region, and their secretions are typically odorless until broken down by bacteria. - **Miliaria** is not associated with the dysfunction or obstruction of apocrine glands.

Question 287: Mouth lesions are seen in:

A. Ichthyosis Vulgaris
B. Psoriasis
C. Lichen Planus (Correct Answer)
D. Basal Cell CA

Explanation: ***Lichen Planus*** - **Oral lichen planus** often presents with characteristic **white, lacy patterns (Wickham's striae)** on the buccal mucosa, tongue, or gingiva. - These lesions can be painful, erosive, or reticular, and are considered a **classic and common manifestation** of the disease. - Oral involvement occurs in **50-70% of lichen planus cases**, making it the most characteristic answer. *Ichthyosis Vulgaris* - This condition is primarily characterized by **dry, scaly skin**, especially on the extremities, due to a problem with keratinization. - **Mouth lesions are not a feature** of ichthyosis vulgaris as it does not affect mucous membranes. *Psoriasis* - While psoriasis primarily affects the skin with **erythematous plaques and silvery scales**, oral manifestations can occur but are **less specific and less common** than in lichen planus. - Associated oral findings include **geographic tongue (benign migratory glossitis)** and fissured tongue, but these are not pathognomonic. - True **oral psoriatic plaques** are rare and non-specific compared to the characteristic Wickham's striae of lichen planus. *Basal Cell CA* - **Basal cell carcinoma (BCC)** is a common skin cancer that rarely appears in the oral cavity. - When it does, it usually presents as a lesion on the **lips** (especially the lower lip at the vermillion border) but is primarily a cutaneous malignancy. - **Not associated with widespread oral mucosal lesions**.

Question 288: Koebner's phenomenon is seen in all of the following except:

A. Darier's disease
B. Molluscum contagiosum
C. Scleromyxedema
D. Erythema multiforme (Correct Answer)

Explanation: ***Erythema multiforme*** - **Erythema multiforme** is an acute hypersensitivity reaction that does **NOT** typically demonstrate the Koebner phenomenon. - Unlike chronic papulosquamous disorders, EM lesions arise from immunologic triggers (infections, drugs) rather than trauma-induced spread. - The characteristic **target lesions** develop in response to antigenic stimuli, not mechanical trauma. *Darier's disease* - **Darier's disease** (keratosis follicularis) is an autosomal dominant disorder that exhibits the Koebner phenomenon. - New keratotic papules develop at sites of trauma, scratching, or friction. - This trauma-induced lesion development is a **key clinical feature** of the disease. *Molluscum contagiosum* - **Molluscum contagiosum** demonstrates the Koebner phenomenon through **autoinoculation**. - Scratching can cause viral spread, resulting in **linear arrangements of lesions** along scratch marks. - This is a classic example of trauma-induced spread in viral skin infections. *Scleromyxedema* - **Scleromyxedema** (generalized lichen myxedematosus) can exhibit the Koebner phenomenon. - New papules may develop at sites of trauma in some cases. - While less commonly emphasized than in psoriasis or lichen planus, Koebnerization has been reported in this condition.

Question 289: Earliest feature of Tuberous sclerosis is:

A. Neurofibroma
B. Ash leaf spot (Correct Answer)
C. Angiofibroma
D. Shagreen patch

Explanation: ***Ash leaf spot*** - **Ash leaf spots**, also known as hypomelanotic macules, are typically the **earliest visible sign** of Tuberous Sclerosis Complex (TSC) and are often present at birth or manifest in early infancy. - These are **lightly pigmented macules** that can be observed using a Wood's lamp, which makes them more apparent. *Neurofibroma* - **Neurofibromas** are characteristic lesions of **Neurofibromatosis Type 1 (NF1)**, not Tuberous Sclerosis Complex. - While they can appear early in life, they are not associated with TSC. *Angiofibroma* - **Facial angiofibromas** (also known as adenoma sebaceum) are common findings in TSC but usually develop later, often appearing in **childhood or adolescence**. - They are typically small, red-to-flesh-colored papules found on the nose and cheeks. *Shagreen patch* - A **shagreen patch** is a connective tissue nevus that appears as a textured, leathery plaque, typically on the lower back or flank. - While characteristic of TSC, it usually becomes noticeable later in childhood and is **not considered the earliest feature**.

Question 290: "Isomorphic response" can be a feature of the following except

A. Tinea (Correct Answer)
B. Warts
C. Molluscum contagiosum
D. Psoriasis

Explanation: ***Tinea*** - The **isomorphic response (Koebner phenomenon)** refers to the development of new skin lesions in areas of trauma due to an immunological process. - This phenomenon is **not typically seen in tinea** (fungal infections). - While tinea can spread to new areas, this occurs through **direct fungal inoculation and contact spread**, not through the true Koebner mechanism. *Warts* - **Warts** caused by human papillomavirus (HPV) can exhibit the **isomorphic response**. - Trauma to the skin can lead to **viral inoculation** in that area, resulting in new wart formation along lines of trauma. - This is a well-recognized example of Koebner phenomenon in viral infections. *Molluscum contagiosum* - **Molluscum contagiosum** (poxvirus infection) can demonstrate the **isomorphic response**. - **Scratching or rubbing** can spread the virus to new areas through autoinoculation. - New lesions develop along the lines of trauma, consistent with Koebner phenomenon. *Psoriasis* - **Psoriasis** is the **classic and most well-known** condition exhibiting the isomorphic response or Koebner phenomenon. - New psoriatic plaques appear in areas of **skin injury** (scratches, cuts, burns, surgical incisions, friction). - Seen in approximately **25-50%** of psoriasis patients.

Practice by Chapter

Structure and Function of Skin

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Cutaneous Histopathology

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Dermatological Examination

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Skin Lesions: Morphology and Description

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Principles of Diagnosis in Dermatology

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Dermatological Procedures

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Wound Healing

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Cutaneous Immunology

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Genetics in Dermatology

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Cutaneous Manifestations of Systemic Diseases

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Geriatric Dermatology

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Pediatric Dermatology Basics

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