Answers and Explanations:

1. In the epidermis:

Correct answer: A. The innermost layer is composed of dividing cells.

• Explanation: The basal layer (stratum basale) of the epidermis contains actively dividing keratinocytes.

• Option analysis:

  • A. The innermost layer is composed of dividing cells: Correct. The basal layer is mitotically active.

  • B. Numerous blood vessels: Incorrect. The epidermis is avascular.

  • C. Stratum corneum is very thick in mucous membranes: Incorrect. It is thinner or absent in mucous membranes.

  • D. Stratum corneum is formed of nucleated cells: Incorrect. The stratum corneum consists of anucleate keratinized cells.

2. The basal cell layer of the epidermis is composed of:

Correct answer: D. Only one single row of cells.

• Explanation: The basal cell layer (stratum basale) consists of a single row of columnar or cuboidal cells.

• Option analysis:

  • A. Cells filled with keratin: Incorrect. Keratinization occurs in upper layers.

  • B. Cells without any organelles: Incorrect. Basal cells contain organelles for division and protein synthesis.

  • C. Three rows of dividing cells: Incorrect. Only one row is present.

  • D. Only one single row of cells: Correct.

3. Cells of the epidermis:

Correct answer: A. Keratinocyte.

• Explanation: Keratinocytes are the primary cell type in the epidermis.

• Option analysis:

  • A. Keratinocyte: Correct. They make up ~90% of epidermal cells.

  • B. Lymphocyte: Incorrect. Found in the dermis, not as a primary epidermal cell.

  • C. Eosinophils: Incorrect. They are white blood cells.

  • D. Fibroblasts: Incorrect. Found in the dermis.

4. The dermis:

Correct answer: B. Divided into papillary layer and reticular layer.

• Explanation: The dermis has two layers: a superficial papillary layer and a deeper reticular layer.

• Option analysis:

  • A. Contains most melanocytes that give the skin its color: Incorrect. Melanocytes are in the basal layer of the epidermis.

  • B. Divided into papillary layer and reticular layer: Correct.

  • C. Blood vessels are rarely found in this layer: Incorrect. The dermis is vascular.

  • D. Is thicker in palms and soles: Correct but secondary; B is more direct.

5. Melanocytes are found in:

Correct answer: C. Stratum basalis.

• Explanation: Melanocytes reside in the basal layer (stratum basale) of the epidermis and produce melanin.

• Option analysis:

  • A. Stratum corneum: Incorrect. No living cells are present.

  • B. Stratum spinosum: Incorrect. Found one layer deeper.

  • C. Stratum basalis: Correct.

  • D. Stratum lucidum: Incorrect. Found only in thick skin.

6. The Keratinization process:

Correct answer: C. Is the travel of cells from the basal layer to the corneal layer with formation of keratin.

• Explanation: Keratinization involves the differentiation of keratinocytes as they migrate upward.

• Option analysis:

  • A. Is the process of cell division in the corneal layer every 28 days: Incorrect. Cell division occurs in the basal layer.

  • B. Is the process of losing keratin and cell organelles: Incorrect. Cells gain keratin and lose organelles.

  • C. Is the travel of cells from basal layer to corneal layer with formation of keratin: Correct.

  • D. While cells travel upward, cell organelles increase in size: Incorrect. Organelles degenerate.

7. Primary skin lesions include:

Correct answer: A. Papules and plaques.

• Explanation: Primary lesions are the initial, unaltered skin manifestations.

• Option analysis:

  • A. Papules and plaques: Correct.

  • B. Erosions and ulcers: Incorrect. These are secondary lesions.

  • C. Hyperkeratosis: Incorrect. Secondary change.

  • D. Atrophic scars: Incorrect. Secondary lesion.

8. Secondary skin lesions include:

Correct answer: C. Lichenification.

• Explanation: Secondary lesions arise from primary lesions or external factors.

• Option analysis:

  • A. Macules and patches: Incorrect. Primary lesions.

  • B. Vesicles and bullae: Incorrect. Primary lesions.

  • C. Lichenification: Correct.

  • D. Keratinocytes: Incorrect. These are cells, not lesions.

9. Crust is a secondary skin lesion defined as:

Correct answer: A. Collection of dried exudates and cellular debris.

• Explanation: Crusts are formed by dried serum, pus, or blood.

• 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.

  • C. Presence of pus regardless of the size: Incorrect. This describes pustules.

  • D. Superficial loss of epidermal continuity: Incorrect. Describes an erosion.

10. Hyperkeratosis is:

Correct answer: A. The thickening of corneal layer.

• Explanation: Hyperkeratosis refers to the thickening of the stratum corneum (the outermost layer of the skin).

• Option analysis:

  • A. The thickening of corneal layer: Correct.

  • B. The thinning of corneal layer: Incorrect. Thinning is called atrophy.

  • C. Absence of corneal layer: Incorrect. Absence would lead to compromised skin barrier.

  • D. The increase in granular layer: Incorrect. Granular layer changes are a separate process.

11. The wheal is the primary lesion of:

Correct answer: C. Urticaria.

• Explanation: Wheals are raised, red, itchy areas commonly seen in urticaria (hives).

• Option analysis:

  • A. Pityriasis rosea: Incorrect. It typically presents as a herald patch and oval lesions.

  • B. Erythema multiformis: Incorrect. Characterized by target lesions, not wheals.

  • C. Urticaria: Correct. Wheals are the hallmark of urticaria.

  • D. Heat rash: Incorrect. Presents with small, red, itchy spots.

12. Tinea Capitis:

Correct answer: D. Diagnosis is confirmed by KOH examination.

• Explanation: KOH (potassium hydroxide) examination is used to detect fungal elements in skin scrapings for diagnosing tinea infections.

• Option analysis:

  • A. Is the dermatophyte infection of glabrous skin: Incorrect. Tinea capitis affects the scalp, not glabrous skin.

  • B. Typical lesion is a plaque covered with crusts: Incorrect. Tinea capitis usually presents as scaly, round patches.

  • C. Topical antifungal (imidazoles or miconazole) is enough to treat the condition: Incorrect. Oral antifungals are required for tinea capitis.

  • D. Diagnosis is confirmed by KOH examination: Correct.

13. Tinea corporis:

Correct answer: C. Appears as scaly patch with elevated margins.

• Explanation: Tinea corporis (ringworm) presents as a ring-shaped lesion with raised, scaly borders.

• Option analysis:

  • A. The superficial fungal infection of the groin: Incorrect. This describes tinea cruris.

  • B. The face is never affected: Incorrect. Tinea corporis can affect the face.

  • C. Appears as scaly patch with elevated margins: Correct.

  • D. Can be treated by Wood's lamp applied in a dark room: Incorrect. Wood's lamp is helpful for diagnosing tinea capitis, not corporis.

14. Tinea cruris:

Correct answer: A. Superficial dermatophyte infection of groin.

• Explanation: Tinea cruris, also known as "jock itch," is a fungal infection of the groin area.

• Option analysis:

  • A. Superficial dermatophyte infection of groin: Correct.

  • B. Patches of localized loss of groin hair covered with fine scales: Incorrect. This more closely describes tinea capitis.

  • C. Typical lesion is a hypopigmented patch with unclear margins: Incorrect. It presents as a well-demarcated, scaly, red patch.

  • D. Systemic antifungal is mandatory for treatment: Incorrect. Topical antifungals are typically sufficient.

13. The following is a viral skin disease:

Correct answer: D. Molluscum contagiosum.

• Explanation: Molluscum contagiosum is a viral skin infection caused by a poxvirus.

• Option analysis:

  • A. Scabies: Incorrect. Scabies is caused by a mite.

  • B. Pediculosis: Incorrect. Pediculosis is a parasitic infestation caused by lice.

  • C. Impetigo contagiosum: Incorrect. Impetigo is bacterial.

  • D. Molluscum contagiosum: Correct.

14. Pityriasis Rosea:

Correct answer: B. Usually starts with the characteristic herald/mother patch.

• Explanation: Pityriasis rosea typically begins with a "herald patch," a large, scaly patch on the body.

• Option analysis:

  • A. If not treated, complications are not preventable: Incorrect. Pityriasis rosea often resolves on its own.

  • B. Usually starts with the characteristic herald/mother patch: Correct.

  • C. Systemic steroids is the available treatment: Incorrect. Steroids are not commonly used; symptomatic treatment is given.

  • D. Topical antibiotics (Fucidic acid) is the treatment of choice: Incorrect. Topical antibiotics are not used for pityriasis rosea.

15. Pityrosporum ovale (Malassezia furfur):

Correct answer: A. Is the causative organism of Tinea versicolor & scalp dandruff.

• Explanation: Malassezia furfur (also called Pityrosporum ovale) is responsible for fungal infections like tinea versicolor and seborrheic dermatitis (scalp dandruff).

• Option analysis:

  • A. Is the causative organism of Tinea versicolor & scalp dandruff: Correct.

  • B. Differentiated from seborrhoeic dermatitis by absence of itching: Incorrect. Seborrheic dermatitis can be itchy, while tinea versicolor is often not.

  • C. Causes hyper-pigmented plaques: Incorrect. Tinea versicolor typically causes hypopigmented or hyperpigmented patches.

  • D. The scalp is commonly affected: Incorrect. The scalp is more affected by seborrheic dermatitis, not tinea versicolor.

16. Which statement is true regarding onchocerciasis:

Correct answer: A. Causative parasite is O. volvulus.

• Explanation: Onchocerciasis, also known as river blindness, is caused by the parasitic worm Onchocerca volvulus.

• Option analysis:

  • A. Causative parasite is O. volvulus: Correct.

  • B. Vector is the river strain of sandfly: Incorrect. The vector is the blackfly, not a sandfly.

  • C. Skin is commonly affected and eyes can never be affected: Incorrect. Onchocerciasis can also affect the eyes.

  • D. Is prevalent only in the Republic of South Sudan: Incorrect. Onchocerciasis is found in many parts of sub-Saharan Africa and parts of Central and South America.

17. Systemic Antifungal is essential in the treatment of:

Correct answer: D. Tinea unghium & Tinea capitis.

• Explanation: Both tinea unghium (onychomycosis) and tinea capitis are difficult to treat with topical antifungals alone, so systemic antifungals like terbinafine or itraconazole are necessary.

• Option analysis:

  • A. Tinea corporis: Incorrect. Usually treated with topical antifungals.

  • B. Tinea cruris: Incorrect. Topical antifungals are sufficient.

  • C. Tinea pedis & Tinea cruris: Incorrect. Most cases can be treated topically.

  • D. Tinea unghium & Tinea capitis: Correct.

18. Acne vulgaris:

Correct answer: B. Apart from the face, it may involve chest and shoulders.

• Explanation: Acne vulgaris primarily affects the face, chest, and shoulders due to the concentration of sebaceous glands.

• Option analysis:

  • A. A disease of sweat glands: Incorrect. Acne involves sebaceous glands.

  • B. Apart from the face, it may involve chest and shoulders: Correct.

  • C. Topical antibiotics can induce scar formation: Incorrect. Scar formation is not a side effect of topical antibiotics.

  • D. Although it appears with puberty, hormonal changes of adolescence has no role: Incorrect. Hormonal changes play a critical role in acne development.

19. Topical treatment of acne vulgaris includes:

Correct answer: C. Topical antibiotics.

• Explanation: Topical antibiotics, such as clindamycin, are commonly used in treating acne vulgaris.

• Option analysis:

  • A. Topical steroids: Incorrect. Steroids can worsen acne.

  • B. Topical antifungal: Incorrect. Antifungals are not used for acne.

  • C. Topical antibiotics: Correct.

  • D. Topical emollient creams: Incorrect. Emollients do not address acne pathogenesis.

20. The pathogenesis of acne vulgaris includes:

Correct answer: A. Follicular hyper-cornification & inflammation.

• Explanation: Acne vulgaris involves follicular hyperkeratinization, sebum overproduction, Propionibacterium acnes infection, and inflammation.

• Option analysis:

  • A. Follicular hyper-cornification & inflammation: Correct.

  • B. Decreased turnover of epidermal cells: Incorrect. There is increased turnover in acne.

  • C. Excess sweating: Incorrect. Sweat glands are not involved in acne.

  • D. Thinning of the sebaceous glands: Incorrect. Sebaceous glands are hyperactive in acne.

21. Impetigo contagiosum:

Correct answer: B. Has two forms: bullous and non-bullous.

• Explanation: Impetigo has two clinical forms: bullous (caused by Staphylococcus aureus) and non-bullous (caused by Staphylococcus aureus or Streptococcus pyogenes).

• Option analysis:

  • A. Covered areas of the body are most affected: Incorrect. Exposed areas are more affected.

  • B. Has two forms: bullous and non-bullous: Correct.

  • C. Lesions are usually in the palms and soles: Incorrect. Lesions occur on the face and extremities.

  • D. Topical treatment is not effective, so systemic treatment must be used in all cases: Incorrect. Topical antibiotics are often sufficient for mild cases.

24. In psoriasis:

Correct answer: C. Presented as plaques covered with silvery scales.

• Explanation: Psoriasis commonly presents as erythematous plaques covered with silvery-white scales, often on extensor surfaces.

• Option analysis:

  • A. Turnover of epidermal cells is very slow: Incorrect. Psoriasis involves rapid turnover of epidermal cells.

  • B. Scalp and nails are never involved: Incorrect. Both are frequently affected.

  • C. Presented as plaques covered with silvery scales: Correct.

  • D. Presented as hyperpigmented macules associated with itching: Incorrect. Psoriasis is not primarily a condition of macules or itching.

25. Treatment of seborrheic dermatitis:

Correct answer: B. Topical steroids or antifungal.

• Explanation: Treatment involves topical antifungal agents (e.g., ketoconazole) or mild topical corticosteroids to reduce inflammation.

• Option analysis:

  • A. Topical anti-acne for seborrheic areas: Incorrect. Acne treatments are not used for seborrheic dermatitis.

  • B. Topical steroids or antifungal: Correct.

  • C. Systemic steroids and antibiotics: Incorrect. These are not typically required.

  • D. Is self-limited and no treatment required: Incorrect. It often requires treatment to control symptoms.

26. Kerion is:

Correct answer: B. Infection of the scalp, being a complication of Tinea capitis.

• Explanation: Kerion is a severe inflammatory response to dermatophyte infection, typically seen in tinea capitis.

• Option analysis:

  • A. Parasitic infection of the scalp associated with pediculosis: Incorrect. It is fungal, not parasitic.

  • B. Infection of the scalp, being a complication of Tinea capitis: Correct.

  • C. A painful ulcer in the scalp: Incorrect. It is not an ulcer but an inflammatory mass.

  • D. Bacterial infection of the hair follicles especially of lower limbs: Incorrect. Kerion is fungal, not bacterial.

27. The cause of Herpes zoster is:

Correct answer: C. Varicella-zoster virus.

• Explanation: Herpes zoster (shingles) is caused by reactivation of the varicella-zoster virus, which also causes chickenpox.

• Option analysis:

  • A. Herpes simplex virus: Incorrect. Causes oral/genital herpes.

  • B. Herpes-zoster virus: Incorrect. No such virus exists.

  • C. Varicella-zoster virus: Correct.

  • D. Corynebacterium: Incorrect. Bacterial, not viral.

28. Folliculitis is the inflammation of:

Correct answer: C. Hair follicles.

• Explanation: Folliculitis is an infection or inflammation of hair follicles, often caused by bacteria like Staphylococcus aureus.

• Option analysis:

  • A. Sebaceous glands: Incorrect. Inflammation of sebaceous glands is seen in acne.

  • B. Sweat glands: Incorrect. Sweat gland inflammation leads to hidradenitis suppurativa.

  • C. Hair follicles: Correct.

  • D. Connective tissue: Incorrect.

29. Comedones:

Correct answer: C. Appear in acne vulgaris as whiteheads or blackheads.

• Explanation: Comedones are characteristic lesions in acne vulgaris. Open comedones (blackheads) result from oxidized keratin, while closed comedones (whiteheads) form due to blocked follicles.

• Option analysis:

  • A. Bacterial infection of the hair follicles especially of lower limbs: Incorrect. Comedones are not infections.

  • B. Parasitic infection of the scalp associated with pediculosis: Incorrect. Comedones are not parasitic.

  • C. Appear in acne vulgaris as whiteheads or blackheads: Correct.

  • D. Is one of the secondary skin lesions: Incorrect. Comedones are primary lesions.

30. Tinea (pityriasis) versicolor is:

Correct answer: B. Characterized by hypo-pigmented or hyper-pigmented patches.

• Explanation: Tinea versicolor is a superficial fungal infection caused by Malassezia species, leading to hypo- or hyper-pigmented scaly patches.

• Option analysis:

  • A. Skin coloured papules and plaques: Incorrect. Lesions are typically scaly patches.

  • B. Characterized by hypo-pigmented or hyper-pigmented patches: Correct.

  • C. Requires no treatment because it is resistant to all methods: Incorrect. Antifungal treatments like topical ketoconazole are effective.

  • D. Dermatophyte infection of the face and neck: Incorrect. It is caused by Malassezia, not dermatophytes.

31. Use of Wood’s light includes examination of:

Correct answer: D. Hair in Tinea capitis.

• Explanation: Wood's light (UV light) is used to detect fungal infections like tinea capitis by fluorescing infected hair.

• Option analysis:

  • A. Burrows in scabies: Incorrect. Wood’s light is not used for scabies.

  • B. Nits (eggs) in pediculosis: Incorrect. Nits are identified visually, not with Wood’s light.

  • C. Nails in Tinea unghium: Incorrect. Wood’s light does not fluoresce on nails.

  • D. Hair in Tinea capitis: Correct.

32. Atopic dermatitis:

Correct answer: A. Has three phases: infantile, childhood, and adult.

• Explanation: Atopic dermatitis progresses through three phases, each with distinct clinical features.

• Option analysis:

  • A. Has three phases: infantile, childhood, and adult: Correct.

  • B. Starts in infants commonly at age of 2 weeks: Incorrect. Typically begins after 2 months of age.

  • C. Usually there is no family history of atopy: Incorrect. Family history is common.

  • D. Can be treated by topical ketoconazole: Incorrect. It is treated with emollients, corticosteroids, and antihistamines, not antifungals.

33. Treatment of viral warts:

Correct answer: A. Cautery and Cryotherapy.

• Explanation: Viral warts are treated by physical methods like cautery, cryotherapy, or chemical agents.

• Option analysis:

  • A. Cautery and Cryotherapy: Correct.

  • B. Highly potent topical steroid: Incorrect. Steroids do not treat warts.

  • C. Topical antiviral: Incorrect. Antivirals are not effective for warts.

  • D. Is a self-limiting and needs no treatment: Incorrect. Many warts require active treatment.

34. Tinea incognito:

Correct answer: B. Obscure lesions of tinea corporis due to use of topical corticosteroids.

• Explanation: Tinea incognito results when corticosteroids mask the typical appearance of dermatophyte infections.

• 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. Lesions are often atypical and altered.

  • D. Super-potent topical steroid will treat the condition: Incorrect. Steroids worsen the condition.

35. Auspitz sign in psoriasis:

Correct answer: C. Mechanical removal of scales results in pin-point bleeding.

• Explanation: Auspitz sign refers to pinpoint bleeding observed when psoriatic scales are removed.

• Option analysis:

  • A. Usually negative in children: Incorrect. It is positive in most cases.

  • B. Appearance of erythema with silvery scales: Incorrect. This describes psoriasis lesions but not the sign.

  • C. Mechanical removal of scales results in pin-point bleeding: Correct.

  • D. Not recommended in plaque type: Incorrect. The sign is often seen in plaque psoriasis.

36. The causative parasite of scabies is:

Correct answer: D. Sarcoptes species.

• Explanation: Scabies is caused by Sarcoptes scabiei var. hominis, a mite that burrows into the skin.

• Option analysis:

  • A. Treponema pallidum: Incorrect. Causes syphilis.

  • B. Pediculus humanus: Incorrect. Causes pediculosis.

  • C. Human Papilloma species: Incorrect. Causes warts.

  • D. Sarcoptes species: Correct.

37. Molluscum contagiosum:

Correct answer: A. Skin-colored papules with a central depression.

• Explanation: Molluscum contagiosum presents as dome-shaped papules with a central dimple.

• Option analysis:

  • A. Skin-colored papules with a central depression: Correct.

  • B. Can never be transmitted sexually: Incorrect. It can be sexually transmitted in adults.

  • C. A disease of unwashed people: Incorrect. Hygiene is not a cause.

  • D. Treated by topical creams or ointments: Incorrect. Requires physical removal or cryotherapy.

38. Chickenpox and herpes zoster:

Correct answer: D. Causative organism is the same for both conditions.

• Explanation: Both conditions are caused by the varicella-zoster virus.

• Option analysis:

  • A. Both start with vesicles containing pus: Incorrect. Vesicles contain clear fluid.

  • B. If chickenpox is not treated, it can proceed to herpes zoster: Incorrect. Herpes zoster occurs from reactivation, not lack of treatment.

  • C. Patients with chickenpox usually have past history of herpes zoster: Incorrect. Herpes zoster occurs after chickenpox, not vice versa.

  • D. Causative organism is the same for both conditions: Correct.

39. Pediculosis corporis:

Correct answer: A. The lice feed on the body, but live in the clothing.

• Explanation: Pediculus humanus corporis lives in clothing seams and feeds on the body.

• Option analysis:

  • A. The lice feed on the body, but live in the clothing: Correct.

  • B. The lice live and feed in the seams of clothing: Incorrect. Feeding occurs on the body.

  • C. They lay eggs in tunnels made in skin: Incorrect. Eggs are laid in clothing seams.

  • D. The parasite uses skin keratin as nutrient: Incorrect. They feed on blood.

40. Scabies:

Correct answer: B. Systemic treatment with ivermectin is the treatment of choice.

• Explanation: Ivermectin is effective for treating scabies, particularly in crusted forms or outbreaks.

• Option analysis:

  • A. There is marked itching during the day: Incorrect. Itching worsens at night.

  • B. Systemic treatment with ivermectin is the treatment of choice: Correct.

  • C. Transmission starts when the parasite takes a blood-meal from a human host: Incorrect. Transmission occurs via direct skin contact.

  • D. Can never be transmitted by sexual contact: Incorrect. It can be sexually transmitted.