Note
Studied by 7 people
Test 3
Here is the complete solution to all the questions, with each option explained to clarify the reasoning for selecting the correct answer.
1. In the epidermis:
Correct answer: C. All layers are derived from the basal cell layer.
Explanation: The epidermis originates from the basal cell layer, which contains mitotically active cells that give rise to all other layers.
Option analysis:
A. In normal skin, stratum corneum is formed of nucleated cells: Incorrect. The stratum corneum consists of anucleate keratinized cells.
B. In mucous membranes, stratum corneum is very thick: Incorrect. Mucous membranes generally have a thinner or absent stratum corneum.
C. All layers are derived from the basal cell layer: Correct.
D. Blood vessels are numerous: Incorrect. The epidermis is avascular; blood vessels are found in the dermis.
E. There are no other cells than keratinocytes: Incorrect. Other cells like melanocytes, Langerhans cells, and Merkel cells are also present.
2. In the epidermis, all these cells are normally present EXCEPT:
Correct answer: C. Lymphocyte.
Explanation: Lymphocytes are not normal resident cells of the epidermis; they are seen in inflammatory or immune responses.
Option analysis:
A. Keratinocyte: Correct. Main structural cell of the epidermis.
B. Melanocyte: Correct. Found in the basal layer, responsible for pigment production.
C. Lymphocyte: Incorrect. Not normally present in the epidermis.
D. Langerhans' cell: Correct. Antigen-presenting cells in the epidermis.
E. Corneocyte (corneal layer cell): Correct. Keratinized cells of the stratum corneum.
3. The basal cell layer of the epidermis is composed of:
Correct answer: A. A single row of cells.
Explanation: The basal cell layer consists of a single layer of columnar or cuboidal cells attached to the basement membrane.
Option analysis:
A. A single row of cells: Correct.
B. Three rows of dividing cells: Incorrect. Only a single layer is actively mitotic.
C. Cells filled with keratin: Incorrect. Basal cells are not keratinized.
D. Papillary cells: Incorrect. Papillary refers to a layer in the dermis.
E. Hair follicles: Incorrect. Hair follicles are not part of the basal layer.
4. The dermis:
Correct answer: C. Divided into papillary layer and reticular layer.
Explanation: The dermis is structurally divided into two layers: the papillary layer (superficial) and the reticular layer (deep).
Option analysis:
A. Composed of non-nucleated cells: Incorrect. Dermis contains fibroblasts, which are nucleated.
B. Melanocytes which give the skin its color, are found in the dermis: Incorrect. Melanocytes are located in the basal layer of the epidermis.
C. Divided into papillary layer and reticular layer: Correct.
D. Blood vessels are rarely found here, they are numerous in the epidermis: Incorrect. Blood vessels are abundant in the dermis but absent in the epidermis.
E. Is thicker in palms and soles: Incorrect. Thickness varies due to stratum corneum rather than dermis.
5. The keratinization process:
Correct answer: D. Is the travel of cells from basal layer to corneal layer with formation of keratin.
Explanation: Keratinization refers to the migration and differentiation of keratinocytes as they move upwards from the basal layer to the stratum corneum, acquiring keratin.
Option analysis:
A. Is the process of cell division that occurs in the corneal layer: Incorrect. Cell division occurs in the basal layer.
B. Is the process of losing of keratin that takes 28 days: Incorrect. Keratin is formed, not lost.
C. Normally takes hours rather than days: Incorrect. It takes approximately 28 days.
D. Is the travel of cells from basal layer to corneal layer with formation of keratin: Correct.
E. While cells travel upward, cell organelles increase in size: Incorrect. Organelles degrade as cells keratinize.
6. Primary skin lesions include:
Correct answer: C. Macule.
Explanation: A macule is a primary skin lesion characterized by a flat, circumscribed discoloration.
Option analysis:
A. Hyperkeratosis: Incorrect. A secondary lesion involving thickened stratum corneum.
B. Erosion: Incorrect. A secondary lesion due to loss of epidermis.
C. Macule: Correct. A primary lesion.
D. Ulcers: Incorrect. A secondary lesion involving full-thickness skin loss.
E. Lichenification: Incorrect. A secondary lesion due to chronic rubbing or scratching.
7. Secondary skin lesions include:
Correct answer: D. Excoriations.
Explanation: Excoriations are classified as secondary lesions resulting from trauma to the skin, often due to scratching.
Option analysis:
A. Papule: Incorrect. Papules are primary lesions, small raised areas of the skin.
B. Vesicle: Incorrect. Vesicles are primary lesions filled with clear fluid.
C. Pustule: Incorrect. Pustules are primary lesions filled with pus.
D. Excoriations: Correct. Secondary lesion caused by loss of epidermis due to trauma.
E. Plaque: Incorrect. Plaques are primary lesions, elevated and larger than papules.
8. Hyperkeratosis
Correct answer: E. Increase in the thickness of the stratum corneum.
Explanation: Hyperkeratosis refers to the excessive production of keratin, resulting in thickening of the stratum corneum, the outermost layer of the epidermis.
Option analysis:
A. Decrease in the thickness of the epidermis: Incorrect. Hyperkeratosis increases thickness.
B. Increase in the thickness of the dermis: Incorrect. It involves the epidermis, not the dermis.
C. Increase in the thickness of the whole epidermis: Incorrect. Hyperkeratosis specifically affects the stratum corneum, not the entire epidermis.
D. Increase in the thickness of basal cell layer: Incorrect. The basal layer is not affected.
E. Increase in the thickness of stratum corneum: Correct.
9. Lichenification means:
Correct answer: C. Increase in the thickness of the whole epidermis.
Explanation: Lichenification is characterized by thickening of the skin with accentuated skin lines due to chronic scratching or rubbing, which increases the overall thickness of the epidermis.
Option analysis:
A. Decrease in the thickness of the epidermis: Incorrect. Lichenification leads to an increase, not a decrease.
B. Increase in the thickness of the dermis: Incorrect. It involves the epidermis, not the dermis.
C. Increase in the thickness of the whole epidermis: Correct.
D. Increase in the thickness of basal cell layer: Incorrect. It affects all layers of the epidermis, not just the basal layer.
E. Increase in the thickness of stratum corneum: Incorrect. While the stratum corneum may be affected, the thickening involves the entire epidermis.
10. Crust is defined as:
Correct answer: A. Collection of dried exudates and cellular debris.
Explanation: Crusts form when serum, blood, or pus dries on the skin surface after an exudative process or injury.
Option analysis:
A. Collection of dried exudates and cellular debris: Correct.
B. Collection of clear fluid of more than 5 mm: Incorrect. This describes a bulla, a primary lesion.
C. Presence of pus regardless of the size: Incorrect. This describes a pustule.
D. Depressed lesion of the skin: Incorrect. Depressed lesions may describe ulcers or erosions.
E. Superficial loss of epidermal continuity: Incorrect. This describes erosion, not crust.
11. Erosion is:
Correct answer: D. Loss of continuity of the surface layers of the skin.
Explanation: Erosion is a secondary lesion involving superficial loss of the epidermis without penetrating the dermis.
Option analysis:
A. Thinning of the skin: Incorrect. Thinning describes atrophy, not erosion.
B. Thickening of the stratum corneum: Incorrect. This describes hyperkeratosis.
C. Post-inflammatory hypopigmentation: Incorrect. This is not related to erosion.
D. Loss of continuity of the surface layers of the skin: Correct.
E. Vertical loss of continuity of layers of the skin: Incorrect. This describes an ulcer, which extends deeper into the dermis.
12. Tinea corporis:
Correct answer: C. Dermatophyte infection of all glabrous skin excluding palms, soles, and groin.
Explanation: Tinea corporis is a fungal infection that affects the skin of the body, sparing hair-covered areas, palms, soles, and groin.
Option analysis:
A. Is a self-limiting disease: Incorrect. It requires antifungal treatment.
B. Patch of localized loss of hair covered with fine scales: Incorrect. This describes tinea capitis.
C. Dermatophyte infection of all glabrous skin excluding palms, soles, and groin: Correct.
D. Typical lesion is a hypopigmented patch with unclear margins: Incorrect. Tinea corporis usually presents with annular lesions with active edges.
E. Typical lesion is a plaque covered with silvery scales: Incorrect. This describes psoriasis.
13. Tinea capitis:
Correct answer: E. Diagnosis is confirmed by KOH examination.
Explanation: Tinea capitis, a fungal scalp infection, is diagnosed using microscopic examination with potassium hydroxide (KOH) to identify fungal hyphae.
Option analysis:
A. Is the dermatophyte infection of beard and moustache: Incorrect. This describes tinea barbae.
B. Typical lesion is a plaque covered with crusted hair: Incorrect. Tinea capitis involves hair loss with scaling.
C. Topical antifungal (imidazoles or miconazole) is enough to treat the condition: Incorrect. Systemic antifungal therapy is required.
D. Treatment is by topical and systemic antibiotics: Incorrect. Antifungals, not antibiotics, are needed.
E. Diagnosis is confirmed by KOH examination: Correct.
14. Systemic antifungal is essential in the treatment of:
Correct answer: E. Tinea unghium & Tinea capitis.
Explanation: Tinea unguium (onychomycosis) and tinea capitis require systemic antifungals because topical treatments are ineffective for deep infections.
Option analysis:
A. Tinea unghium: Partially correct. Requires systemic antifungals.
B. Tinea cruris: Incorrect. Typically treated with topical antifungals.
C. Tinea capitis: Partially correct. Requires systemic antifungals.
D. Tinea unghium & Tinea cruris: Incorrect. Tinea cruris does not usually require systemic treatment.
E. Tinea unghium & Tinea capitis: Correct.
15. The causative organism of Herpes zoster is:
Correct answer: C. Varicella-zoster virus.
Explanation: Herpes zoster, also known as shingles, is caused by the reactivation of the varicella-zoster virus (VZV), the same virus that causes chickenpox.
Option analysis:
A. Herpes simplex virus: Incorrect. This causes oral and genital herpes, not herpes zoster.
B. Herpes-zoster virus: Incorrect. There is no separate herpes-zoster virus; it’s caused by varicella-zoster virus.
C. Varicella-zoster virus: Correct.
D. Corynebacterium: Incorrect. This is a bacterial genus unrelated to herpes zoster.
E. Unknown: Incorrect. The causative virus is well-known.
16. Herpes zoster:
Correct answer: E. The causative virus is dormant in the posterior root ganglia after a chickenpox infection.
Explanation: After chickenpox resolves, the varicella-zoster virus remains dormant in the dorsal root ganglia. Reactivation can occur later in life, especially during periods of immunosuppression.
Option analysis:
A. Appears as generalized vesicle: Incorrect. Herpes zoster appears as a unilateral, dermatomal rash.
B. Affects individuals in middle age with good immunity: Incorrect. It often affects older adults or immunocompromised individuals.
C. Herpetic neuralgia may precede vesicle appearance: Incorrect. Postherpetic neuralgia occurs after the rash, not before.
D. Affected individuals have past history of Herpes simplex infection: Incorrect. It is related to chickenpox, not herpes simplex.
E. The causative virus is dormant in the posterior root ganglia after a chickenpox infection: Correct.
17. Viral warts can be treated with all of these methods EXCEPT:
Correct answer: D. Highly potent topical steroids.
Explanation: Topical steroids have no role in treating viral warts. Effective methods include physical removal (e.g., cautery, cryotherapy) and chemical destruction.
Option analysis:
A. Cautery and electrical burn: Correct. An effective treatment method.
B. Chemical destruction: Correct. Includes salicylic acid or similar agents.
C. Cryotherapy by liquid nitrogen: Correct. A widely used and effective treatment.
D. Highly potent topical steroids: Incorrect. Steroids do not address viral infections.
E. Removal by curette: Correct. Physical removal is an option.
18. Kerion is:
Correct answer: C. Fungal infection of the scalp, being a complication of Tinea capitis.
Explanation: Kerion is an inflammatory response to a severe fungal scalp infection, often associated with tinea capitis. It is characterized by swollen, tender, boggy plaques with hair loss.
Option analysis:
A. Bacterial infection of the hair follicles especially of lower limbs: Incorrect. Describes folliculitis, not kerion.
B. Parasitic infection of the scalp associated with pediculosis: Incorrect. Pediculosis refers to lice infestation, not kerion.
C. Fungal infection of the scalp, being complication of Tinea capitis: Correct.
D. A painful genital ulcer: Incorrect. Describes chancroid or herpes, not kerion.
E. A viral infection of the skin: Incorrect. Kerion is caused by dermatophytes, not viruses.
19. Pityriasis Rosea:
Correct answer: C. Usually starts with the characteristic herald (mother) patch.
Explanation: Pityriasis rosea typically begins with a herald patch, a single, large, scaly lesion, followed by a widespread rash.
Option analysis:
A. Appears as painful plaque in the trunk: Incorrect. Pityriasis rosea is usually asymptomatic or mildly pruritic.
B. If not treated, complications are not preventable: Incorrect. It is a self-limiting condition with minimal complications.
C. Usually starts with the characteristic herald (mother) patch: Correct.
D. Systemic steroids is the available treatment: Incorrect. Steroids are not typically used; symptomatic relief may involve antihistamines or topical emollients.
E. Topical antifungal is the best treatment: Incorrect. Antifungals are not indicated.
20. The causative parasite of scabies is:
Correct answer: E. Sarcoptes species.
Explanation: Scabies is caused by Sarcoptes scabiei, a microscopic mite that burrows into the skin, causing intense pruritus.
Option analysis:
A. Treponema pallidum: Incorrect. This causes syphilis.
B. Pediculus humanus: Incorrect. This causes lice infestation.
C. Haemophilus ducreyi: Incorrect. This bacterium causes chancroid.
D. Leishmania donovani: Incorrect. This parasite causes visceral leishmaniasis, not scabies.
E. Sarcoptes species: Correct.
21. The following skin diseases are caused by viruses EXCEPT:
Correct answer: B. Impetigo contagiosum.
Explanation: Impetigo is caused by bacteria, typically Staphylococcus aureus or Streptococcus pyogenes.
Option analysis:
A. Molluscum contagiosum: Incorrect. Caused by a poxvirus.
B. Impetigo contagiosum: Correct. Caused by bacteria, not a virus.
C. Warts: Incorrect. Caused by human papillomavirus (HPV).
D. Herpes zoster: Incorrect. Caused by varicella-zoster virus.
E. Chickenpox: Incorrect. Caused by varicella-zoster virus.
22. Acne vulgaris:
Correct answer: C. Apart from the face it may involve chest and shoulders.
Explanation: Acne vulgaris primarily affects sebaceous gland-rich areas like the face, chest, and shoulders.
Option analysis:
A. A disease of sweat glands: Incorrect. It is a disease of sebaceous glands.
B. Although it appears with puberty, hormonal changes of adolescence has no role: Incorrect. Hormonal changes play a significant role in its development.
C. Apart from the face it may involve chest and shoulders: Correct.
D. Topical or systemic antibiotics has no role in treatment: Incorrect. Antibiotics are a mainstay of treatment.
E. Required no treatment: Incorrect. Acne often requires treatment to prevent scarring.
23. The pathogenesis of Acne vulgaris:
Correct answer: A. Increase in sebum production.
Explanation: Acne vulgaris is caused by increased sebum production, keratinization of the follicular epithelium leading to blockage, bacterial colonization (Cutibacterium acnes), and inflammation.
Option analysis:
A. Increase in sebum production: Correct. Hormonal changes during puberty stimulate sebaceous glands, leading to excessive sebum production.
B. Increase in sweating mainly in hot seasons: Incorrect. Acne is not caused by sweating.
C. Increase in the turn-over of basal cells: Incorrect. While keratinocyte turnover contributes, it is not the primary factor.
D. Blockage of sebaceous glands by keratin: Incorrect. This is a contributing factor but not the sole cause.
E. Inflammation of subcutaneous tissues: Incorrect. Inflammation occurs, but it is secondary to other processes like sebum production.
24. Pityrosporum ovale (Malassezia furfur):
Correct answer: E. All of the above.
Explanation: Malassezia furfur causes a variety of skin conditions, including pityriasis versicolor, dandruff, and seborrheic dermatitis. It also leads to hypo- or hyperpigmented patches due to its effect on melanin production.
Option analysis:
A. Is the causative organism of Pityriasis versicolour: Correct.
B. Is the causative organism for scalp dandruff: Correct.
C. Triggers seborrheic dermatitis: Correct.
D. Causes hypo- or hyper-pigmented patches: Correct.
E. All of the above: Correct.
25. Molluscum Contagiosum:
Correct answer: C. In adults, is commonly transmitted by sexual contact.
Explanation: Molluscum contagiosum is a viral skin infection caused by a poxvirus. In adults, lesions are often transmitted sexually, and they appear on the genital or lower abdominal area.
Option analysis:
A. Despite the name, it is not contagious: Incorrect. It is highly contagious.
B. A disease of children, and never occurs in adults: Incorrect. While common in children, it also affects adults.
C. In adults, is commonly transmitted by sexual contact: Correct.
D. Lesions are usually in covered, sun-protected parts: Incorrect. Lesions can appear anywhere, often on exposed areas in children and genital areas in adults.
E. Treatment by topical antiviral: Incorrect. Treatment usually involves physical removal (e.g., curettage or cryotherapy).
26. Tinea incognito:
Correct answer: B. Obscure lesions of tinea corporis due to use of topical corticosteroids.
Explanation: Tinea incognito is a fungal infection altered by inappropriate use of topical corticosteroids, which suppress inflammation but allow fungal proliferation.
Option analysis:
A. Is the superficial dermatophyte infection of the groin: Incorrect. This describes tinea cruris.
B. Obscure lesions of tinea corporis due to use of topical corticosteroids: Correct.
C. Typical lesions are tiny pustules in the affected area: Incorrect. Tinea incognito often presents atypically.
D. Super-potent topical steroid will treat the condition: Incorrect. Steroids worsen the condition.
E. Is a yeast infection commonly affects children: Incorrect. Dermatophytes, not yeasts, are the causative organisms.
27. Impetigo contagiosum:
Correct answer: B. Caused by Staphylococcus or Streptococcus.
Explanation: Impetigo is a highly contagious bacterial skin infection caused by Staphylococcus aureus or Streptococcus pyogenes.
Option analysis:
A. Covered areas of the body are most affected: Incorrect. Exposed areas, like the face, are commonly involved.
B. Caused by Staphylococcus or Streptococcus: Correct.
C. Lesions are usually in the palms and soles: Incorrect. Lesions are typically around the face or extremities.
D. Systemic treatment must be used in all cases: Incorrect. Localized cases can often be treated with topical antibiotics.
E. Adults are affected more than children: Incorrect. It primarily affects children.
28. Auspitz sign in psoriasis:
Correct answer: D. Mechanical removal of scales results in pin-point bleeding.
Explanation: The Auspitz sign is a hallmark of psoriasis, where removal of scales reveals tiny bleeding points due to capillary exposure.
Option analysis:
A. Its degree will help selection of the best treatment: Incorrect. The sign does not guide treatment choice.
B. Usually negative in children: Incorrect. The sign is present regardless of age.
C. Appearance of erythema with silvery scales: Incorrect. This describes the general appearance of psoriasis, not the Auspitz sign.
D. Mechanical removal of scales results in pin-point bleeding: Correct.
E. Not recommended in plaque type: Incorrect. The sign is a diagnostic clue, not a treatment method.
29. Eleven-year-old female with localized loss of scalp hair and dome-shaped lesion with yellow crusts in her brother:
Correct answer: C. Tinea capitis must be excluded by KOH examination in both conditions.
Explanation: Tinea capitis is a fungal scalp infection. KOH examination confirms the diagnosis. The dome-shaped lesion with yellow crusts in the brother indicates a kerion, a complication of untreated tinea capitis.
Option analysis:
A. The first differential diagnosis is Alopecia areata: Incorrect. Alopecia areata does not present with scales or crusts.
B. These are two different conditions that are not related: Incorrect. Both conditions suggest fungal infection.
C. Tinea capitis must be excluded by KOH examination in both conditions: Correct.
D. Topical treatment is required in both conditions: Incorrect. Systemic treatment is often required for kerion and severe tinea capitis.
E. Tinea capitis is excluded because it never occurs in females: Incorrect. Tinea capitis can occur in both genders.
30. Chickenpox:
Correct answer: D. Appear as vesicles preceded by fever.
Explanation: Chickenpox is caused by varicella-zoster virus. It typically starts with fever and malaise, followed by a vesicular rash.
Option analysis:
A. Caused by pox virus: Incorrect. It is caused by varicella-zoster virus, not a poxvirus.
B. The treatment of choice is low potency topical steroids: Incorrect. Antiviral therapy or symptomatic treatment is used; steroids are not indicated.
C. Is not infectious: Incorrect. Chickenpox is highly contagious.
D. Appear as vesicles preceded by fever: Correct.
E. Appears as generalized patches: Incorrect. The lesions are vesicular.