Pigmentary Disorders Practice Questions

Q: Which condition is characterized by the presence of hypopigmented macules?

Tuberous sclerosis. ***Tuberous sclerosis*** - **Hypopigmented macules**, often described as **ash-leaf spots**, are a classic cutaneous manifestation of tuberous sclerosis. - These spots are usually present from birth or early infancy and are an important diagnostic criterion for the condition. *Addison's disease* - Characterized by **hyperpigmentation**, particularly in sun-exposed areas, skin folds, and mucous membranes, due to increased ACTH stimulating melanocytes. - It does not typically present with hypopigmented macules. *Porphyria* - Manifests with various skin findings, including **photosensitivity**, blistering, increased fragility, and hair growth, but not primary hypopigmented macules. - The skin changes are often related to the accumulation of porphyrins in the skin. *Cutaneous mastocytosis* - Characterized by accumulations of **mast cells** in the skin, leading to lesions that can include **urticaria pigmentosa** (reddish-brown macules or papules that urticate when rubbed). - It does not typically present with hypopigmented macules as a primary feature.

Q: A melanocytic nevus surrounded by a depigmented halo is called:

Sutton's nevus. ***Sutton's nevus*** - A **Sutton's nevus**, also known as a **halo nevus**, is characterized by a central **melanocytic nevus** encircled by a zone of **depigmentation**. - This depigmented halo is thought to be an immune response targeting the melanocytes within the nevus and sometimes in the surrounding skin. *Meyerson's nevus* - A **Meyerson's nevus** is a melanocytic nevus surrounded by a patch of **eczematous inflammation**. - It presents with redness, scaling, and itching, which are not features of a depigmented halo. *Cockade nevus* - A **cockade nevus** typically appears as a targetoid lesion with distinct concentric rings of varying pigmentation. - It does not feature a completely depigmented halo surrounding the central nevus. *Nevus anemicus* - **Nevus anemicus** is a congenital vascular anomaly where localized vasoconstriction or reduced vascular responsiveness creates a persistent **pale patch** that does not redden with rubbing. - It is not a melanocytic nevus and the paleness is due to vascular changes, not an absence of melanin.

Q: Schamberg's purpura is seen on?

Feet. ***Feet*** - Schamberg's purpura, also known as **progressive pigmented purpuric dermatosis**, most commonly affects the **lower extremities**, particularly the feet and ankles. - The characteristic reddish-brown patches with "cayenne pepper" spots are due to **capillary inflammation** and extravasation of red blood cells. *Face* - While purpura can occur on the face due to other conditions, Schamberg's purpura **rarely presents in this location**. - Facial lesions often suggest different underlying etiologies, such as **vasculitis** or trauma. *Chest* - The chest is an **uncommon site** for Schamberg's purpura. - Involvement of the trunk is less typical compared to the dependent areas of the legs. *Arms* - Although the arms can occasionally be affected, the **feet and lower legs are the predominant sites** for Schamberg's purpura due to factors like **gravity** and hydrostatic pressure. - When present on the arms, it might indicate a more widespread or atypical presentation.

Q: Brown macular pigmentation in malar area in a pregnant female is due to ?

Chloasma. ***Chloasma*** - **Chloasma**, also known as the **mask of pregnancy**, is characterized by **dark, irregular patches** of hyperpigmentation on the face, commonly in the malar areas. - It is caused by an increase in **estrogen and progesterone levels** during pregnancy, which stimulate melanin production. *Acanthosis nigricans* - This condition presents as **dark, velvety patches of skin**, typically in the body folds and creases, such as the neck, armpits, and groin. - It is often associated with **insulin resistance**, obesity, or underlying malignancies, not specifically pregnancy-induced facial pigmentation. *Urticaric pigmentosa* - This is a form of **mastocytosis** characterized by reddish-brown spots or patches that can **urticate (itch and swell)** when rubbed, a sign known as **Darier's sign**. - It results from an accumulation of **mast cells** in the skin and is not related to hormonal changes in pregnancy. *Acne rosacea* - **Acne rosacea** is a chronic inflammatory skin condition primarily affecting the face, causing **redness, flushing, visible blood vessels**, and sometimes bumps or pimples. - It is unrelated to hyperpigmentation and does not typically result in brown macular pigmentation.

Q: Which of the following skin lesions is not classified as a nevus of melanocytes?

Becker nevus. ***Becker nevus*** - A **Becker nevus** is a **hamartoma** of the **epidermis, dermis, and hair follicles**, characterized by increased epidermal basal layer pigmentation and smooth muscle hyperplasia. - While it contains increased **melanin**, it does **not** involve a proliferation of **melanocytes** themselves, differentiating it from true melanocytic nevi. - It is an **organoid hamartoma** with epidermal and dermal components, not a melanocytic lesion. *Mongolian spot* - A **Mongolian spot** is a **dermal melanocytosis** where melanocytes are entrapped in the dermis during their migration from the neural crest to the epidermis. - While technically termed a "melanocytosis" rather than a "nevus," it represents an **ectopic collection of dermal melanocytes** and is classified among melanocytic lesions. - Unlike Becker nevus, it involves an actual abnormal distribution of melanocytes (not just increased melanin). *Congenital melanocytic nevus* - A **congenital melanocytic nevus** is a benign proliferation of **melanocytes** present at birth, involving the dermis and/or epidermis. - These are true **melanocytic nevi**, with a risk of malignant transformation, particularly in larger lesions (>20 cm). *Dysplastic nevus* - A **dysplastic nevus** (atypical nevus) is an atypical melanocytic nevus with architectural and cytological atypia, considered a potential precursor to melanoma. - It is classified as a **melanocytic nevus** due to the proliferation of atypical melanocytes with architectural disorder.

Q: Raindrop pigmentation is caused by?

Arsenic. ***Arsenic*** - Chronic **arsenic** exposure can lead to characteristic skin manifestations, including **raindrop pigmentation**, which appears as small, scattered hypopigmented macules surrounded by hyperpigmented skin, particularly on the trunk and extremities. - This pigmentation is a result of altered **melanin distribution** and **keratinocyte damage** due to arsenic toxicity. *Clofazimine* - **Clofazimine** is an anti-leprosy drug that can cause **reddish-brown to bluish-black skin discoloration**, which is a diffuse pigmentation, not "raindrop" in nature. - The pigmentation associated with clofazimine is due to drug deposition in tissues and is usually reversible. *Dapsone* - **Dapsone** is primarily known for causing **methemoglobinemia** and **hemolytic anemia**, especially in patients with G6PD deficiency. - While it can cause some dermatological side effects, **pigmentation** is not a characteristic feature, and it does not produce a "raindrop" pattern. *Minocycline* - **Minocycline** can cause various types of pigmentation, including **blue-gray discoloration** in scars, shins, and mucous membranes, as well as diffuse brown pigmentation. - However, the pigmentation caused by minocycline is typically diffuse or localized to specific areas, and it does not present as "raindrop pigmentation."

Q: Which of the following conditions is not typically associated with vitiligo?

Crohn's disease. ***Crohn's disease*** - While Crohn's disease is an autoimmune/inflammatory condition, it is **not typically linked** to vitiligo. - Its systemic manifestations primarily involve **gastrointestinal symptoms**, with skin involvement usually being **erythema nodosum** or **pyoderma gangrenosum**, not depigmentation. - The autoimmune mechanisms in Crohn's target the gut, not melanocytes. *Addison's disease* - This condition is an autoimmune disorder that affects the adrenal glands and is **frequently associated with vitiligo**. - Both conditions share common **genetic predispositions** and immune mechanisms. - Part of **autoimmune polyendocrine syndrome** spectrum. *Pernicious anemia* - Pernicious anemia is an autoimmune disorder targeting gastric parietal cells, leading to **vitamin B12 deficiency**, and is **known to be associated with vitiligo**. - This association is due to shared **autoimmune pathways** affecting different tissues. - Commonly seen together in autoimmune clustering. *Hashimoto's thyroiditis* - **Autoimmune thyroid disease** is one of the **most common conditions associated with vitiligo**. - Up to 20-30% of vitiligo patients have **thyroid autoantibodies**. - Both conditions involve **autoimmune destruction** of specific cell types (thyroid follicular cells and melanocytes respectively).

Q: Large unilateral hypopigmented lesions on the right trunk and arm in a female are best explained by which of the following?

Neurogenic theory. ***Neurogenic theory*** - This theory posits that **neural mechanisms** play a role in the development of some hypopigmented disorders. The **unilateral distribution** along a dermatome or nerve pathway strongly supports a neurogenic origin. - The **large, unilateral hypopigmented lesions on the right trunk and arm** are characteristic of conditions like **segmental vitiligo** or **hypopigmentation following nerve injury**, where neural factors are implicated in melanocyte dysfunction. *Autoimmune theory* - The autoimmune theory explains **generalized vitiligo**, where the body's immune system attacks melanocytes, leading to widespread depigmentation. - It does not account for the **segmental, unilateral distribution** observed in this case, which is typically not seen in autoimmune conditions. *Genetic predisposition* - While genetics can increase susceptibility to certain pigmentary disorders, it does not explain the **unilateral, segmental pattern** of hypopigmentation. - Genetic factors usually lead to more generalized or bilateral presentations rather than a localized, nerve-distribution pattern. *Lerner's self-destruct theory* - **Lerner's self-destruct theory** suggests that melanocytes may destroy themselves from within due to metabolic defects or oxidative stress. - This theory also fails to explain the **unilateral, dermatomal distribution** of the lesions, as self-destruction would likely occur more randomly or symmetrically.

Q: What is the minimum number of café au lait macules required as one of the diagnostic criteria for Neurofibromatosis type 1 (NF1)?

6. ***6*** - According to the National Institutes of Health (NIH) diagnostic criteria for **Neurofibromatosis type 1 (NF1)**, individuals must have **six or more café au lait macules** greater than 5 mm in greatest diameter in prepubertal individuals and greater than 15 mm in postpubertal individuals. - The presence of six or more café au lait macules is a key diagnostic feature, especially when combined with other criteria such as **neurofibromas, optic pathway gliomas, or Lisch nodules**. *1* - A single **café au lait macule** is a common finding in the general population and does not meet the diagnostic threshold for **neurofibromatosis**. - While one might be present in an individual with NF1, it is insufficient on its own to fulfill this specific diagnostic criterion. *2* - While a higher number than one, two café au lait macules still falls short of the **established diagnostic criteria** for neurofibromatosis. - The diagnostic criteria are set to increase the specificity of diagnosis for complex genetic disorders like **NF1**. *4* - Four café au lait macules are more than commonly seen in the general population but still do not reach the **minimum threshold of six** required for the diagnostic criterion of neurofibromatosis. - The number six is specifically chosen to differentiate between benign skin findings and characteristic features of **NF1**.

Question 1

Which condition is characterized by the presence of hypopigmented macules?

Accepted Answer

Tuberous sclerosis

Answer

Addison's disease

Answer

Porphyria

Answer

Cutaneous mastocytosis

Question 2

What is a common skin finding in patients with Fanconi's anemia?

Accepted Answer

Hyperpigmentation of the trunk, neck, and intertriginous areas.

Answer

Multiple seborrheic keratoses.

Answer

Telangiectasias on sun-exposed areas.

Answer

Palmar and plantar keratoderma.

Question 3

A melanocytic nevus surrounded by a depigmented halo is called:

Accepted Answer

Sutton's nevus

Answer

Nevus anemicus

Answer

Meyerson's nevus

Answer

Cockade nevus

Question 4

Schamberg's purpura is seen on?

Accepted Answer

Feet

Answer

Face

Answer

Chest

Answer

Arms

Question 5

Brown macular pigmentation in malar area in a pregnant female is due to ?

Accepted Answer

Chloasma

Answer

Urticaric pigmentosa

Answer

Acanthosis nigricans

Answer

Acne rosacea

Question 6

Which of the following skin lesions is not classified as a nevus of melanocytes?

Accepted Answer

Becker nevus

Answer

Dysplastic nevus

Answer

Congenital melanocytic nevus

Answer

Mongolian spot

Question 7

Raindrop pigmentation is caused by?

Accepted Answer

Arsenic

Answer

Dapsone

Answer

Minocycline

Answer

Clofazimine

Question 8

Which of the following conditions is not typically associated with vitiligo?

Accepted Answer

Crohn's disease

Answer

Pernicious anemia

Answer

Addison's disease

Answer

Hashimoto's thyroiditis

Question 9

Large unilateral hypopigmented lesions on the right trunk and arm in a female are best explained by which of the following?

Accepted Answer

Neurogenic theory

Answer

Autoimmune theory

Answer

Genetic predisposition

Answer

Lerner's self-destruct theory

Question 10

What is the minimum number of café au lait macules required as one of the diagnostic criteria for Neurofibromatosis type 1 (NF1)?

Accepted Answer

6

Answer

1

Answer

2

Answer

4

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

On this page

Practice by Chapter

Want unlimited practice?