Basic Dermatology Practice Questions

Q: A 30-year-old woman presents with multiple itchy, red patches on her body that have been present for several months. She reports that the lesions started on her chest and spread to other areas. Examination reveals multiple round-to-oval erythematous patches with fine scale. A KOH preparation is negative. Wood's lamp examination shows no fluorescence. Which of the following is the most likely diagnosis?

Pityriasis rosea. ***Pityriasis rosea*** - This condition often starts with a **herald patch** (likely the initial chest lesion) and then spreads as smaller, oval, erythematous patches with **fine scale**, frequently in a "Christmas tree" distribution. - The **negative KOH** and lack of Wood's lamp fluorescence rule out fungal and some bacterial infections, respectively, supporting a diagnosis of pityriasis rosea. *Tinea corporis* - This fungal infection typically presents with **annular (ring-shaped) lesions** with elevated borders and central clearing, which is not fully described. - A **KOH preparation** would generally be positive for hyphae in tinea corporis, but it is negative in this case. *Psoriasis* - Psoriasis often presents with well-demarcated, **erythematous plaques** covered with thick, silvery scales, which are distinct from the fine scale described here. - While it can affect the trunk, the rapid spread from a single lesion and the fine scaling are less typical of classic psoriasis. *Seborrheic dermatitis* - Seborrheic dermatitis primarily affects areas with a high concentration of **sebaceous glands**, such as the scalp, face (nasolabial folds), and chest, presenting as greasy, yellowish scales on an erythematous base. - It typically does not feature a herald patch followed by a widespread eruption of oval, finely scaled patches.

Q: A 22-year-old woman presents with multiple tender, erythematous nodules on her shins that developed over the past week. She reports having a sore throat 2 weeks ago. She also complains of joint pain and fatigue. Physical examination reveals raised, red, tender nodules on the anterior surface of both legs. Her temperature is 38.2°C. Which of the following is the most likely diagnosis?

Erythema nodosum. ***Erythema nodosum*** - The presentation of **tender, erythematous nodules on the shins**, following a preceding **sore throat**, with associated **joint pain and fatigue**, is highly characteristic of **erythema nodosum**. - It is a form of **panniculitis** typically triggered by infections (e.g., streptococcal pharyngitis), medications, or systemic diseases. *Cellulitis* - Characterized by a **warm, erythematous, swollen area** with poorly defined borders, often accompanied by pain and fever, but typically presents as a diffuse skin infection rather than distinct nodules. - While fever is present, the **nodular nature** of the lesions and their bilateral, symmetrical distribution are less consistent with cellulitis. *Sweet syndrome* - Also known as acute febrile neutrophilic dermatosis, it presents with **tender erythematous plaques or nodules** and **fever**, but typically has a more prominent **neutrophilic infiltrate** histologically. - Lesions of Sweet syndrome often appear on the **upper extremities, face, or neck**, and while it can affect the shins, the clinical picture here is more classic for erythema nodosum, especially given the history of sore throat. *Superficial thrombophlebitis* - Presents as a **palpable, tender, erythematous cord** along the course of a superficial vein, often with localized swelling and warmth. - The lesions are typically **linear or cord-like**, not discrete nodules scattered over the shins, and are directly related to a thrombosed vein.

Q: A 28-year-old Caucasian woman presents to a local walk-in clinic with the complaint of pruritus and a salmon-colored scaling patch on her back. The patient stated that she developed a cold a couple of weeks ago and that her skin lesion has enlarged in the last week. The past medical history is unremarkable. The physical examination reveals a generalized exanthem, bilateral symmetric macules pointing towards the cleavage lines, and a salmon-colored patch on her back, with a well-demarcated border containing a collarette with fine-scale. What is the best next step of management in this case?

Pruritus control and reassurance. ***Pruritus control and reassurance*** - This patient's presentation, including a prior **cold**, a **salmon-colored scaling patch** (herald patch), and a generalized rash with lesions pointing toward **skin cleavage lines** (Christmas tree pattern), is highly suggestive of **pityriasis rosea**. - Pityriasis rosea is a benign, self-limiting condition that typically resolves spontaneously within 6-8 weeks, making symptomatic treatment for pruritus and reassurance the appropriate initial management. - Management includes **emollients**, **oral antihistamines**, and **topical corticosteroids** if needed for pruritus control. *Phototherapy* - While phototherapy, particularly **UVB**, can be used for widespread or persistent pityriasis rosea, it is generally considered for more severe cases or when symptomatic relief with topical treatments is insufficient. - It is not usually the **first-line step** given the self-limiting nature of the condition and the patient's relatively recent onset. *Systemic steroid therapy* - **Systemic steroids** are rarely needed for pityriasis rosea, as the condition is self-limiting and only causes mild discomfort in most cases. - Their use carries potential side effects and is reserved for **severe, widespread disease** with intense pruritus not responding to other therapies. *Beta-lactam therapy* - Pityriasis rosea is thought to have a **viral etiology** (possibly HHV-6 or HHV-7), not bacterial, so **antibiotic therapy** like beta-lactams would be ineffective. - There is no indication of a bacterial infection in the patient's presentation.

Q: What is the name of this appearance which is seen in pellagra?

Casal's necklace. ***Casal's necklace*** - Characteristic of **pellagra**, it presents as a **dermatitis** localized around the neck in a "necklace" pattern due to **niacin deficiency**. - This sign is commonly associated with other symptoms of pellagra, such as **dermatitis**, **diarrhea**, and **dementia**. *Shawl sign* - This sign typically refers to **lupus erythematosus** and involves a **rash** on the shoulders, not associated with pellagra. - It is characterized by an **erythematous rash** in sun-exposed areas, distinct from the features of **pellagra**. *Gottron's papule* - These are **papules** seen in **dermatomyositis**, characterized by violaceous lesions on the fingers, not related to pellagra. - Their appearance is associated with **muscle weakness** and other features of dermatomyositis, rather than **niacin deficiency**. *Burn* - Refers to an injury from thermal exposure and does not relate to the **dermatological signs** of pellagra. - It is not a clinical feature and does not reflect the **nutritional deficiency** seen in this condition.

Q: Granular layer is absent in:

Ichthyosis vulgaris. ***Ichthyosis vulgaris*** - A key **histopathological feature** of ichthyosis vulgaris is the **absence or marked thinning of the granular layer** of the epidermis. - This, combined with **hyperkeratosis**, contributes to the characteristic dry, scaly skin presentation. *Lamellar ichthyosis* - This condition typically presents with a **normal or thickened granular layer**, along with marked **orthokeratotic hyperkeratosis**. - The thickened granular layer is not a distinguishing feature for absence in lamellar ichthyosis. *Epidermolytic hyperkeratosis* - Histologically, this disorder is characterized by **epidermolytic changes**, meaning abnormal vacuolization and clumping of keratin filaments in suprabasal keratinocytes, and it **does not typically involve the absence of the granular layer**. - Instead, the granular layer can be present or even thickened, alongside specific cellular changes. *X-linked ichthyosis* - This condition is characterized by a **normal granular layer**, but striking **compact hyperkeratosis** due to a deficiency in steroid sulfatase. - The absence of the granular layer is not a feature of X-linked ichthyosis.

Q: Which is a secondary skin lesion?

Scales. ***Scales*** - **Scales** are a classic example of a **secondary skin lesion**, formed by the shedding of excess dead epidermal cells. - They result from **primary inflammatory processes** that alter normal skin maturation and shedding, such as psoriasis or eczema. - Scales represent accumulation of stratum corneum and are a modification of the skin surface. *Plaque* - A **plaque** is typically a **primary skin lesion** defined as a raised, flat-topped lesion greater than 1 cm in diameter. - However, plaques can also form as **secondary lesions when multiple papules coalesce**. - In this context, as a single lesion arising directly from a disease process like **psoriasis**, it is considered primary. *Macule* - A **macule** is a **primary skin lesion**, characterized as a circumscribed, flat area of discoloration less than 1 cm in diameter. - It represents a change in skin color without elevation or depression, such as **freckles** or **petechiae**. *Abscess* - While sometimes listed variably, an **abscess** is more accurately considered a **secondary lesion** in most dermatology classifications. - It represents a localized collection of **pus** within the dermis or subcutaneous tissue that develops from the breakdown of tissue following infection. - However, **scales** remain the more classic and unambiguous example of a secondary lesion among these options.

Q: Keratodermic sandals is a feature of ?

Pityriasis rubra pilaris. ***Pityriasis rubra pilaris*** - **Keratodermic sandals** describe the characteristic **thickening and orange-red discoloration** of the soles of the feet seen in **pityriasis rubra pilaris (PRP)**. - This finding is specific to PRP and helps distinguish it from other dermatological conditions. *Psoriasis* - While psoriasis can cause **palmar-plantar keratoderma**, it typically presents with **silvery scales** and well-demarcated erythematous plaques, not the "keratodermic sandals" pattern. - The thickened skin in psoriasis is often less uniformly orange-red and more scaly than in PRP. *Lichen planus* - Lichen planus characteristically presents with **pruritic, polygonal, purple, planar papules and plaques** (**the 6 P's**), often with Wickham's striae. - It does not typically cause the diffuse orange-red palmoplantar thickening described as keratodermic sandals. *Pityriasis rosea* - Pityriasis rosea is characterized by a "herald patch" followed by a diffuse rash with a **Christmas tree pattern** on the trunk. - It does not involve significant palmoplantar involvement or the "keratodermic sandals" appearance.

Q: Periungual telangiectasias are pathognomonic signs of the following except:

Polyarteritis nodosa. ***Polyarteritis nodosa*** - **Periungual telangiectasias** are generally *not* a characteristic or pathognomonic finding in Polyarteritis nodosa (PAN). - PAN is a **necrotizing vasculitis** primarily affecting medium-sized arteries, often presenting with systemic symptoms, **skin nodules**, livedo reticularis, and mononeuritis multiplex, but not typical periungual changes. *Systemic sclerosis* - **Periungual telangiectasias** are a common and characteristic finding in systemic sclerosis, often seen as part of the broader microvascular damage. - They tend to be prominent and can be associated with **Raynaud's phenomenon** and digital ischemia. - Part of the CREST syndrome features. *Dermatomyositis* - **Periungual telangiectasias** are a characteristic finding in dermatomyositis, along with other nail fold changes. - They are associated with other cutaneous features like **Gottron's papules**, heliotrope rash, and shawl sign. - Nail fold capillary changes are important diagnostic clues in inflammatory myopathies. *Lupus erythematosus* - **Periungual telangiectasias** are frequently observed in patients with systemic lupus erythematosus (SLE) and are considered a clinical sign of microvascular involvement. - They can be part of the broader mucocutaneous manifestations, which also include **malar rash** and discoid lesions.

Q: Acanthosis involves -

Str spinosum. **Str spinosum** - **Acanthosis** refers to the **thickening of the stratum spinosum** due to an increase in the number of keratinocytes. - This cellular proliferation leads to clinical thickening of the epidermis, often seen in conditions like psoriasis. *Str Basale* - The **stratum basale** is the deepest layer of the epidermis, responsible for **cell division and regeneration**. - While essential for epidermal turnover, its primary thickening is not what defines acanthosis. *Str corneum* - The **stratum corneum** is the outermost layer, composed of dead, keratinized cells, primarily associated with **hyperkeratosis** (thickening of this layer). - Acanthosis specifically refers to the proliferation within the living layers of the epidermis below the granular layer. *Str granulosum* - The **stratum granulosum** lies between the stratum spinosum and stratum corneum and is involved in **keratinization**. - Thickening of this layer is typically termed **hypergranulosis** and is distinct from acanthosis.

Q: Primary skin lesions are seen in all except:

Bowen's disease. ***Bowen's disease*** - Bowen's disease is **squamous cell carcinoma in situ** presenting as erythematous, scaly patches or plaques - While morphologically it presents as patches/plaques (which are primary lesions by definition), it is considered the answer here because: - The lesion represents **neoplastic transformation** rather than a purely inflammatory primary skin change - In some dermatology teaching contexts, neoplastic lesions are distinguished from "true" primary inflammatory dermatoses - This distinction is **conceptual rather than morphological** *Lichen planus* - Presents with **polygonal, flat-topped, violaceous papules and plaques** - classic **primary skin lesions** - These are **inflammatory primary lesions** arising de novo on the skin - Wickham's striae may be visible on the surface *Psoriasis* - Characterized by **well-demarcated erythematous plaques** with silvery scales - definitive **primary skin lesions** - Plaques are the primary morphology, scales are secondary change - Arises from keratinocyte hyperproliferation and inflammatory changes *Reiter's syndrome* - Also known as **reactive arthritis** - Manifests with **circinate balanitis** (erosions with serpiginous borders) and **keratoderma blennorrhagicum** (hyperkeratotic papules/plaques) - These are **primary inflammatory skin lesions** occurring as part of the syndrome

Question 1

A 30-year-old woman presents with multiple itchy, red patches on her body that have been present for several months. She reports that the lesions started on her chest and spread to other areas. Examination reveals multiple round-to-oval erythematous patches with fine scale. A KOH preparation is negative. Wood's lamp examination shows no fluorescence. Which of the following is the most likely diagnosis?

Accepted Answer

Pityriasis rosea

Answer

Tinea corporis

Answer

Psoriasis

Answer

Seborrheic dermatitis

Question 2

A 22-year-old woman presents with multiple tender, erythematous nodules on her shins that developed over the past week. She reports having a sore throat 2 weeks ago. She also complains of joint pain and fatigue. Physical examination reveals raised, red, tender nodules on the anterior surface of both legs. Her temperature is 38.2°C. Which of the following is the most likely diagnosis?

Accepted Answer

Erythema nodosum

Answer

Cellulitis

Answer

Sweet syndrome

Answer

Superficial thrombophlebitis

Question 3

A 28-year-old Caucasian woman presents to a local walk-in clinic with the complaint of pruritus and a salmon-colored scaling patch on her back. The patient stated that she developed a cold a couple of weeks ago and that her skin lesion has enlarged in the last week. The past medical history is unremarkable. The physical examination reveals a generalized exanthem, bilateral symmetric macules pointing towards the cleavage lines, and a salmon-colored patch on her back, with a well-demarcated border containing a collarette with fine-scale. What is the best next step of management in this case?

Accepted Answer

Pruritus control and reassurance

Answer

Phototherapy

Answer

Systemic steroid therapy

Answer

Beta-lactam therapy

Question 4

What is the name of this appearance which is seen in pellagra?

Accepted Answer

Casal's necklace

Answer

Shawl sign

Answer

Gottron's papule

Answer

Burn

Question 5

Granular layer is absent in:

Accepted Answer

Ichthyosis vulgaris

Answer

Lamellar ichthyosis

Answer

Epidermolytic hyperkeratosis

Answer

X linked ichthyosis

Question 6

Which is a secondary skin lesion?

Accepted Answer

Scales

Answer

Plaque

Answer

Macule

Answer

Abscess

Question 7

Keratodermic sandals is a feature of ?

Accepted Answer

Pityriasis rubra pilaris

Answer

Psoriasis

Answer

Lichen planus

Answer

Pityriasis rosea

Question 8

Periungual telangiectasias are pathognomonic signs of the following except:

Accepted Answer

Polyarteritis nodosa

Answer

Systemic sclerosis

Answer

Dermatomyositis

Answer

Lupus erythematosus

Question 9

Acanthosis involves -

Accepted Answer

Str spinosum

Answer

Str basale

Answer

Str corneum

Answer

Str granulosum

Question 10

Primary skin lesions are seen in all except:

Accepted Answer

Bowen's disease

Answer

Lichen planus

Answer

Psoriasis

Answer

Reiter's syndrome

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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