INI-CET 2021 — Dermatology

Q: A young girl presents with leukotrichia and lesions as shown in the image. What is the most likely diagnosis?

Segmental vitiligo. ***Segmental vitiligo*** - Segmental vitiligo characteristically presents as unilateral, **dermatomal** or **quasi-dermatomal depigmentation** with sharply demarcated borders, often including overlying **leukotrichia** (white hairs) in the affected area, as seen in the image. - This form typically has an early onset, rapid progression followed by stabilization, and can be more resistant to conventional treatments than non-segmental vitiligo. *Piebaldism* - Piebaldism is a **congenital leukoderma** characterized by a **white forelock** and symmetrically distributed depigmented patches, primarily on the trunk and extremities, which are usually stable in size and present from birth. - Unlike the progressive nature and unilateral pattern seen in the image, piebaldism is a genetic condition without new lesion development or the characteristic dermatomal distribution. *Focal vitiligo* - Focal vitiligo refers to one or a few localized depigmented macules that do not have a segmental pattern and are not distributed along a specific dermatome. - While it involves localized depigmentation, the clear **segmental distribution** and presence of **leukotrichia** in the image are more indicative of segmental vitiligo. *Nevus depigmentosus* - Nevus depigmentosus is a congenital, **stable hypopigmented lesion** that typically appears as a solitary patch or macule, without subsequent growth or change in size over time. - The lesions shown in the image appear to be multiple and follow a distinct pattern that is not typical of a stable, solitary nevus. [Practice more Dermatology PYQs on OnCourse]

Q: A child presented with itchy plaques over the neck, the bilateral popliteal and cubital fossa. What could be the diagnosis?

Atopic dermatitis. **Atopic dermatitis** - The presentation of **itchy plaques** in the anatomical locations described (neck, bilateral popliteal fossa, and cubital fossa) is highly characteristic of **atopic dermatitis** in children. - Atopic dermatitis typically involves **flexural surfaces** in older children and adults, and is characterized by **intense pruritus**. *Dermatitis herpetiformis* - This condition presents with **extremely itchy, grouped vesicles and papules**, primarily on extensor surfaces, buttocks, and scalp. - It is strongly associated with **celiac disease** and is unlikely to present as plaques in flexural areas. *Psoriasis* - Psoriasis typically presents with **well-demarcated, erythematous plaques** covered with **silvery scales**, often on extensor surfaces (knees, elbows) and the scalp. - While it can occur in flexural areas (inverse psoriasis), **itching is usually less prominent** than in atopic dermatitis, and the characteristic scaling is usually present. *Pemphigus vegetans* - Pemphigus vegetans is a rare variant of pemphigus, characterized by **verrucous, vegetative lesions** and **bullae**, often in intertriginous areas. - This condition is a chronic autoimmune blistering disease and does not typically present as simple itchy plaques in a child. [Practice more Dermatology PYQs on OnCourse]

Q: A child presented with asymptomatic lesions on the forearm and on the shaft of the penis. The lesions on the forearm are shown below. What is the most likely diagnosis?

Lichen nitidus. ***Lichen nitidus*** - Presents as **multiple, asymptomatic, tiny (1-2 mm), shiny, dome-shaped papules** that are often skin-colored or slightly hypopigmented, as seen in the image and described. - Common sites include the **forearms, penis, abdomen, and flexural areas**, consistent with the case presentation. *Lichen planus* - Characterized by **purplish, polygonal, planar, pruritic papules and plaques**, often with **Wickham's striae**, which are not seen in the image. - While it can affect the penis, its lesions are typically more intensely colored and often symptomatic (**itchy**), unlike the asymptomatic lesions described. *Scabies* - Presents with intensely **pruritic papules, vesicles, and burrows**, especially in the web spaces of fingers, wrists, axillae, and genitalia, which are very symptomatic and not usually described as shiny papules. - The primary symptom is **severe itching**, which is absent in this patient. *Scrofuloderma* - A form of **cutaneous tuberculosis** presenting as cold abscesses that eventually rupture to form ulcers, sinuses, and scars. - The image shows distinct, small papules, not ulcerating or scarring lesions characteristic of scrofuloderma. [Practice more Dermatology PYQs on OnCourse]

Q: A young man presented with painful vesicular lesions distributed along a dermatomal pattern on one side of his body. What is the likely diagnosis?

Herpes Zoster. ***Herpes Zoster*** - This condition is characterized by a **unilateral rash** that respects the **dermatomal distribution**, meaning it follows the path of a single nerve. - The lesions are typically **painful vesicles** and crusts, often associated with a burning sensation due to reactivation of the **varicella-zoster virus** (chickenpox virus). *Lymphangioma circumscriptum* - This is a rare **lymphatic malformation** presenting as clusters of **vesicles** or papules, often described as 'frog spawn' or 'tapioca pudding' in appearance. - While it can be painful, it usually does not follow a dermatomal pattern and is a congenital condition, not an acute viral eruption. *Molluscum contagiosum* - This is a viral skin infection producing small, firm, **umbilicated papules** that are typically flesh-colored or pearly. - While contagious, these lesions are generally **asymptomatic** and do not present with the acute pain, blistering, or dermatomal distribution characteristic of herpes zoster. *Herpes simplex* - This infection causes localized clusters of painful **vesicles** on an erythematous base, most commonly around the mouth (cold sores) or genitals. - Unlike herpes zoster, herpes simplex lesions typically recur in the same small area and do **not follow a dermatomal distribution**. [Practice more Dermatology PYQs on OnCourse]

4 Previous Year Questions with Answers & Explanations

Questions

A young girl presents with leukotrichia and lesions as shown in the image. What is the most likely diagnosis?

A child presented with itchy plaques over the neck, the bilateral popliteal and cubital fossa. What could be the diagnosis?

A child presented with asymptomatic lesions on the forearm and on the shaft of the penis. The lesions on the forearm are shown below. What is the most likely diagnosis?

A young man presented with painful vesicular lesions distributed along a dermatomal pattern on one side of his body. What is the likely diagnosis?

INI-CET 2021 - Dermatology INI-CET Practice Questions and MCQs

Question 1: A young girl presents with leukotrichia and lesions as shown in the image. What is the most likely diagnosis?

A. Segmental vitiligo (Correct Answer)
B. Piebaldism
C. Focal vitiligo
D. Nevus depigmentosus

Explanation: ***Segmental vitiligo*** - Segmental vitiligo characteristically presents as unilateral, **dermatomal** or **quasi-dermatomal depigmentation** with sharply demarcated borders, often including overlying **leukotrichia** (white hairs) in the affected area, as seen in the image. - This form typically has an early onset, rapid progression followed by stabilization, and can be more resistant to conventional treatments than non-segmental vitiligo. *Piebaldism* - Piebaldism is a **congenital leukoderma** characterized by a **white forelock** and symmetrically distributed depigmented patches, primarily on the trunk and extremities, which are usually stable in size and present from birth. - Unlike the progressive nature and unilateral pattern seen in the image, piebaldism is a genetic condition without new lesion development or the characteristic dermatomal distribution. *Focal vitiligo* - Focal vitiligo refers to one or a few localized depigmented macules that do not have a segmental pattern and are not distributed along a specific dermatome. - While it involves localized depigmentation, the clear **segmental distribution** and presence of **leukotrichia** in the image are more indicative of segmental vitiligo. *Nevus depigmentosus* - Nevus depigmentosus is a congenital, **stable hypopigmented lesion** that typically appears as a solitary patch or macule, without subsequent growth or change in size over time. - The lesions shown in the image appear to be multiple and follow a distinct pattern that is not typical of a stable, solitary nevus.

Question 2: A child presented with itchy plaques over the neck, the bilateral popliteal and cubital fossa. What could be the diagnosis?

A. Dermatitis herpetiformis
B. Psoriasis
C. Pemphigus vegetans
D. Atopic dermatitis (Correct Answer)

Explanation: **Atopic dermatitis** - The presentation of **itchy plaques** in the anatomical locations described (neck, bilateral popliteal fossa, and cubital fossa) is highly characteristic of **atopic dermatitis** in children. - Atopic dermatitis typically involves **flexural surfaces** in older children and adults, and is characterized by **intense pruritus**. *Dermatitis herpetiformis* - This condition presents with **extremely itchy, grouped vesicles and papules**, primarily on extensor surfaces, buttocks, and scalp. - It is strongly associated with **celiac disease** and is unlikely to present as plaques in flexural areas. *Psoriasis* - Psoriasis typically presents with **well-demarcated, erythematous plaques** covered with **silvery scales**, often on extensor surfaces (knees, elbows) and the scalp. - While it can occur in flexural areas (inverse psoriasis), **itching is usually less prominent** than in atopic dermatitis, and the characteristic scaling is usually present. *Pemphigus vegetans* - Pemphigus vegetans is a rare variant of pemphigus, characterized by **verrucous, vegetative lesions** and **bullae**, often in intertriginous areas. - This condition is a chronic autoimmune blistering disease and does not typically present as simple itchy plaques in a child.

Question 3: A child presented with asymptomatic lesions on the forearm and on the shaft of the penis. The lesions on the forearm are shown below. What is the most likely diagnosis?

A. Lichen planus
B. Lichen nitidus (Correct Answer)
C. Scabies
D. Scrofuloderma

Explanation: ***Lichen nitidus*** - Presents as **multiple, asymptomatic, tiny (1-2 mm), shiny, dome-shaped papules** that are often skin-colored or slightly hypopigmented, as seen in the image and described. - Common sites include the **forearms, penis, abdomen, and flexural areas**, consistent with the case presentation. *Lichen planus* - Characterized by **purplish, polygonal, planar, pruritic papules and plaques**, often with **Wickham's striae**, which are not seen in the image. - While it can affect the penis, its lesions are typically more intensely colored and often symptomatic (**itchy**), unlike the asymptomatic lesions described. *Scabies* - Presents with intensely **pruritic papules, vesicles, and burrows**, especially in the web spaces of fingers, wrists, axillae, and genitalia, which are very symptomatic and not usually described as shiny papules. - The primary symptom is **severe itching**, which is absent in this patient. *Scrofuloderma* - A form of **cutaneous tuberculosis** presenting as cold abscesses that eventually rupture to form ulcers, sinuses, and scars. - The image shows distinct, small papules, not ulcerating or scarring lesions characteristic of scrofuloderma.

Question 4: A young man presented with painful vesicular lesions distributed along a dermatomal pattern on one side of his body. What is the likely diagnosis?

A. Lymphangioma circumscriptum
B. Molluscum contagiosum
C. Herpes simplex
D. Herpes Zoster (Correct Answer)

Explanation: ***Herpes Zoster*** - This condition is characterized by a **unilateral rash** that respects the **dermatomal distribution**, meaning it follows the path of a single nerve. - The lesions are typically **painful vesicles** and crusts, often associated with a burning sensation due to reactivation of the **varicella-zoster virus** (chickenpox virus). *Lymphangioma circumscriptum* - This is a rare **lymphatic malformation** presenting as clusters of **vesicles** or papules, often described as 'frog spawn' or 'tapioca pudding' in appearance. - While it can be painful, it usually does not follow a dermatomal pattern and is a congenital condition, not an acute viral eruption. *Molluscum contagiosum* - This is a viral skin infection producing small, firm, **umbilicated papules** that are typically flesh-colored or pearly. - While contagious, these lesions are generally **asymptomatic** and do not present with the acute pain, blistering, or dermatomal distribution characteristic of herpes zoster. *Herpes simplex* - This infection causes localized clusters of painful **vesicles** on an erythematous base, most commonly around the mouth (cold sores) or genitals. - Unlike herpes zoster, herpes simplex lesions typically recur in the same small area and do **not follow a dermatomal distribution**.