Basic Dermatology Practice Questions

Q: A 40 year old man with a known case of chronic pancreatitis presents to the OPD with complaint of skin pigmentation over the abdomen. The patient gives a history of chronic use of a hot water bottle to relieve the abdominal discomfort. Which one of the following is the most appropriate diagnosis?

Erythema ab igne. ***Erythema ab igne*** - This condition is caused by **chronic exposure to moderate heat**, which aligns with the patient's history of using a hot water bottle for abdominal discomfort. - It presents as **reticulated erythema** and **hyperpigmentation** on the affected skin, precisely matching the description of skin pigmentation over the abdomen. *Erythema infectiosum* - This is also known as **Fifth disease** and is caused by **Parvovirus B19**. - It typically presents with a characteristic **"slapped cheek" rash** on the face and a lacy rash on the trunk and limbs, which is not consistent with the patient's presentation. *Erythema marginatum* - This is a rare, transient rash associated with **acute rheumatic fever**. - It presents as **pink-red macules with clear centers and serpiginous borders** that migrate, which does not fit the described chronic pigmentation. *Erythema nodosum* - This condition is characterized by **tender, red nodules** typically found on the **shins**. - It is a form of **panniculitis** (inflammation of subcutaneous fat) and is not caused by chronic heat exposure, nor does it present as diffuse pigmentation.

Q: A patient presents with orange-hued skin lesions and hyperkeratotic palms and soles. A biopsy shows alternating parakeratosis and orthokeratosis. What is the most likely diagnosis?

Pityriasis rubra pilaris. ***Pityriasis rubra pilaris*** - This condition classically presents with **salmon-colored to orange-hued plaques** and **hyperkeratotic palms and soles**. - Histologically, Pityriasis rubra pilaris is characterized by **alternating parakeratosis and orthokeratosis** in vertical and horizontal directions ("checkerboard" pattern). *Follicular psoriasis* - While psoriasis can present with hyperkeratosis and scales, **follicular psoriasis** specifically involves the hair follicles, seen as follicular papules and pustules. - The classic alternating parakeratosis and orthokeratosis is more indicative of PRP than of follicular psoriasis, which typically shows more uniform parakeratosis. *Keratosis follicularis* - Also known as Darier disease, this condition presents with **greasy, crusted, foul-smelling papules** on seborrheic areas. - Histopathology reveals characteristic **dyskeratosis** with acantholytic cells (corps ronds and grains), which is different from the described alternating parakeratosis and orthokeratosis. *Ichthyosis vulgaris* - This is a genetic disorder characterized by **dry, scaly skin** due to impaired epidermal barrier function, often worse in winter. - Histopathology typically shows a **diminished or absent granular layer** and compact orthokeratosis without parakeratosis, differing from the biopsy findings.

Q: A patient's skin biopsy shows a box-shaped or square-shaped pattern of inflammatory infiltrate, as shown in the image. What is the most likely diagnosis?

Lichen planus. ***Lichen planus*** - The image shows a characteristic **"box-shaped" or "square-shaped" infiltrate** of lymphocytes at the dermal-epidermal junction, obscuring the basal layer. - Other features consistent with lichen planus include **hypergranulosis**, **sawtooth rete ridges**, and **Civatte bodies** (apoptotic keratinocytes) in the basal layer. *Lichen amyloidosis* - This condition is characterized by deposition of **amyloid material** in the papillary dermis, often associated with keratinocyte necrosis. - While it can present with pruritic papules similar to lichen planus, the histology specifically shows **amyloid deposits**, not the typical basal cell damage or band-like infiltrate seen in the image. *Morphea* - Morphea is a form of localized scleroderma, characterized by **thickening of collagen bundles** in the dermis and subcutaneous tissue, leading to hardened skin plaques. - Histologically, it involves **sclerosis** and homogenization of collagen, with a sparse inflammatory infiltrate, which is distinct from the dense band-like infiltrate and epidermal changes shown. *Lichen nitidus* - Lichen nitidus is characterized by **small, discrete granulomas** within the papillary dermis (the "ball-and-claw" appearance), with epithelial extensions embracing the inflammatory infiltrate. - It involves a more **localized inflammatory process** and distinct granulomatous appearance, rather than the broad, band-like infiltrate seen across the dermal-epidermal junction in this image.

Q: A patient who has always neglected his nutrition presented with follicular hyperkeratosis on the extensor aspect of the forearm. What is the diagnosis?

Phrynoderma. ***Phrynoderma*** - **Phrynoderma**, also known as **toad skin**, is characterized by **follicular hyperkeratosis**, particularly on the **extensor surfaces** of limbs like the forearm. - This condition is closely linked to **nutritional deficiencies**, often involving **vitamin A**, **essential fatty acids**, or sometimes **B vitamins**. *Eruptive xanthoma* - **Eruptive xanthomas** are small, yellow-red papules that often appear suddenly, typically on the **buttocks**, **extensor surfaces of the limbs**, and **trunk**. - They are a cutaneous manifestation of **severe hypertriglyceridemia** and not primarily related to general nutritional neglect or follicular hyperkeratosis. *Darier's disease* - **Darier's disease** is a **rare, inherited genetic disorder** characterized by greasy, crusted papules primarily in **seborrheic areas** such as the scalp, forehead, chest, and groin. - It results from a mutation in the **ATP2A2 gene**, affecting calcium signaling in keratinocytes, and is not a nutritional deficiency condition. *Folliculitis* - **Folliculitis** is the inflammation of one or more **hair follicles**, often caused by **bacterial** (e.g., *Staphylococcus aureus*) or **fungal infections**. - It presents as small, red, sometimes pus-filled bumps around hair follicles, distinct from the dry, rough texture of follicular hyperkeratosis seen in phrynoderma.

Q: A young girl presents to the outpatient department with rough-surfaced lesions over her elbows and knees. She also complains of diminished vision at night. What is the most likely diagnosis?

Phrynoderma. ***Phrynoderma*** - Phrynoderma, also known as **follicular hyperkeratosis**, presents with **rough, horny papules** over extensor surfaces like elbows and knees, often described as "toad skin." - It is a skin manifestation of **vitamin A deficiency**, which also causes **night blindness** (nyctalopia) due to impaired production of rhodopsin. *Folliculitis* - This is an **inflammation of hair follicles**, appearing as small, red bumps or pustules centered around hair follicles. - It is typically caused by bacterial or fungal infections and does not cause **night blindness**. *Pyoderma* - **Pyoderma** refers to a **pus-producing skin infection** caused by bacteria, such as impetigo or cellulitis. - These are characterized by crusts, blisters, or inflamed lesions and are not associated with **rough skin** or **night blindness**. *Keratosis pilaris* - This common genetic condition causes small, rough bumps, typically on the upper arms, thighs, and buttocks, due to **keratin plugging hair follicles**. - While it causes rough skin similar to phrynoderma, it is generally **benign** and does not cause systemic symptoms like **night blindness**.

Q: Match the following scale types with their lesions. | Scales | Lesions | | :-- | :-- | | 1. Collarette scales | a. Pityriasis versicolour | | 2. Silvery scales | b. Pityriasis rosea | | 3. Mica-like scales | c. Psoriasis | | 4. Branny scales | d. Pityriasis lichenoides |

1-b, 2-c, 3-d, 4-a. ***1-b, 2-c, 3-d, 4-a*** - **Collarette scales** are pathognomonic of **Pityriasis rosea**, appearing as fine, trailing scales around the periphery of oval lesions in a "Christmas tree" distribution. - **Silvery scales** are the classic hallmark of **Psoriasis**, presenting as thick, adherent, silvery-white scales overlying well-demarcated erythematous plaques. - **Mica-like scales** are characteristic of **Pityriasis lichenoides**, appearing as thick, shiny, adherent scales that can be peeled off like mica sheets. - **Branny scales** are typical of **Pityriasis versicolor**, presenting as fine, powdery scales caused by **Malassezia** yeast overgrowth. *1-d, 2-c, 3-a, 4-b* - Incorrectly matches **collarette scales with Pityriasis lichenoides**, which typically presents with mica-like scales, not collarette scales. - Misassociates **mica-like scales with Pityriasis versicolor**, which characteristically has branny (fine, powdery) scales. *1-c, 2-b, 3-d, 4-a* - Wrongly pairs **collarette scales with Psoriasis**, which is known for thick silvery scales, not peripheral collarette scales. - Incorrectly matches **silvery scales with Pityriasis rosea**, which has collarette scales at lesion periphery, not silvery scales. *1-a, 2-b, 3-d, 4-c* - Falsely associates **collarette scales with Pityriasis versicolor**, which has branny scales from yeast infection, not collarette scales. - Mismatches **branny scales with Psoriasis**, which has characteristic thick silvery scales, not fine powdery scales.

Q: A 24-year-old male presents with asymptomatic scaly lesions over the body as shown in the image below. What is the likely diagnosis?

Pityriasis Rosea. ***Pityriasis Rosea*** - The image shows numerous **scaly, erythematous plaques** distributed over the trunk, with a characteristic "Christmas tree" pattern often observed in Pityriasis Rosea. - The lesions are described as **asymptomatic**, which is consistent with Pityriasis Rosea, although mild pruritus can occur. *Atopic Dermatitis* - Typically presents with **intensely pruritic, erythematous, and eczematous lesions** often found in flexural areas (e.g., antecubital and popliteal fossae). - While it can be widespread, the morphology of the lesions (eczematous vs. scaly plaques) and the absence of pruritus make this less likely. *Lichen planus* - Characterized by **pruritic, violaceous, polygonal papules** and plaques, often appearing on the flexor surfaces of wrists, ankles, and oral mucosa. - The appearance of the lesions in the image does not match the typical morphology of lichen planus. *Seborrheic Dermatitis* - Primarily affects areas with a high density of sebaceous glands, such as the **scalp, face (nasolabial folds, eyebrows), and chest**. - Presents with **greasy, yellowish scales** on an erythematous base, which is distinct from the dry, scaly plaques seen in the image.

Q: Match the following woods lamp findings: 1. Erythrasma, 2. Pityriasis versicolor, 3. Tinea capitis, 4. Vitiligo || a. Yellow b. Coral red fluorescence c. Pink d. Green e. Milky white

1-b, 2-a, 3-d, 4-e. ***1-b, 2-a, 3-d, 4-e*** - **Erythrasma** is caused by *Corynebacterium minutissimum* and produces **porphyrins** that fluoresce **coral red** under a Wood's lamp [1]. - **Pityriasis versicolor** is caused by *Malassezia furfur* and typically fluoresces **yellow to yellowish-green** [2]. - **Tinea capitis** (especially due to *Microsporum* species) shows **green fluorescence** of infected hairs. - **Vitiligo** lesions, due to a complete absence of melanin, appear as **milky white** or bright white areas under a Wood's lamp [3]. *1-d, 2-a, 3-c, 4-e* - This option incorrectly states that Erythrasma fluoresces green. Green fluorescence is characteristic of *Microsporum* species causing **Tinea capitis**. - Additionally, Tinea capitis is incorrectly associated with pink fluorescence, which is not a typical finding. *1-a, 2-c, 3-e, 4-d* - This option incorrectly states that Erythrasma fluoresces yellow. Yellow fluorescence is associated with **Pityriasis versicolor** [2]. - It also incorrectly assigns milky white fluorescence to Tinea capitis and green fluorescence to Vitiligo. *1-b, 2-d, 3-a, 4-c* - This option incorrectly associates Pityriasis versicolor with green fluorescence. While some variations exist, **yellow** is the more characteristic finding [2]. - It also incorrectly links Tinea capitis to yellow fluorescence and Vitiligo to pink, which are not typical Wood's lamp findings for these conditions.

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.

Question 1

A 40 year old man with a known case of chronic pancreatitis presents to the OPD with complaint of skin pigmentation over the abdomen. The patient gives a history of chronic use of a hot water bottle to relieve the abdominal discomfort. Which one of the following is the most appropriate diagnosis?

Accepted Answer

Erythema ab igne

Answer

Erythema infectiosum

Answer

Erythema marginatum

Answer

Erythema nodosum

Question 2

A patient presents with orange-hued skin lesions and hyperkeratotic palms and soles. A biopsy shows alternating parakeratosis and orthokeratosis. What is the most likely diagnosis?

Accepted Answer

Pityriasis rubra pilaris

Answer

Follicular psoriasis

Answer

Keratosis follicularis

Answer

Ichthyosis vulgaris

Question 3

A patient's skin biopsy shows a box-shaped or square-shaped pattern of inflammatory infiltrate, as shown in the image. What is the most likely diagnosis?

Accepted Answer

Lichen planus

Answer

Lichen amyloidosis

Answer

Morphea

Answer

Lichen nitidus

Question 4

A patient who has always neglected his nutrition presented with follicular hyperkeratosis on the extensor aspect of the forearm. What is the diagnosis?

Accepted Answer

Phrynoderma

Answer

Eruptive xanthoma

Answer

Darier's disease

Answer

Folliculitis

Question 5

A young girl presents to the outpatient department with rough-surfaced lesions over her elbows and knees. She also complains of diminished vision at night. What is the most likely diagnosis?

Accepted Answer

Phrynoderma

Answer

Folliculitis

Answer

Pyoderma

Answer

Keratosis pilaris

Question 6

Match the following scale types with their lesions.

Accepted Answer

1-b, 2-c, 3-d, 4-a

Answer

1-d, 2-c, 3-a, 4-b

Answer

1-c, 2-b, 3-d, 4-a

Answer

1-a, 2-b, 3-d, 4-c

Question 7

A 24-year-old male presents with asymptomatic scaly lesions over the body as shown in the image below. What is the likely diagnosis?

Accepted Answer

Pityriasis Rosea

Answer

Atopic Dermatitis

Answer

Lichen planus

Answer

Seborrheic Dermatitis

Question 8

Match the following woods lamp findings: 1. Erythrasma, 2. Pityriasis versicolor, 3. Tinea capitis, 4. Vitiligo || a. Yellow  b. Coral red fluorescence c. Pink  d. Green e. Milky white

Accepted Answer

1-b, 2-a, 3-d, 4-e

Answer

1-d, 2-a, 3-c, 4-e

Answer

1-a, 2-c, 3-e, 4-d

Answer

1-b, 2-d, 3-a, 4-c

Question 9

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 10

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

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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