Pigmentary Disorders Practice Questions

Q: Which of the following is the reason for the development of a simple lentigo?

Increased melanocytes. **Explanation:** The core pathological feature of **Simple Lentigo** (Lentigo Simplex) is a **linear hyperplasia of melanocytes** at the dermo-epidermal junction. Unlike a freckle, which is a functional change, a lentigo represents a structural change where there is an actual increase in the number of pigment-producing cells. * **Option B (Correct):** In simple lentigo, there is a proliferation of melanocytes along the basal layer. Histologically, this is accompanied by "dirty" elongated rete ridges (club-shaped) and increased melanin in both the melanocytes and basal keratinocytes. * **Option A & C (Incorrect):** While increased melanin and melanosomes are *present* in a lentigo, they are secondary consequences of the increased number of melanocytes. If only melanin or melanosomes were increased without an increase in cell number, the lesion would be classified as an **Ephelis (Freckle)**. **NEET-PG High-Yield Pearls:** 1. **Lentigo vs. Freckle:** * **Lentigo:** Increased number of melanocytes; does **not** darken with sun exposure. * **Freckle (Ephelis):** Normal number of melanocytes but increased melanin production; **does** darken with sun exposure. 2. **Histology:** Look for "club-shaped" elongation of rete ridges and melanocytic hyperplasia without nesting (nesting would indicate a Nevus). 3. **Clinical Associations:** Multiple lentigines are associated with syndromes like **LEOPARD syndrome** (PTPN11 mutation) and **Peutz-Jeghers syndrome** (perioral lentigines). 4. **Lentigo Senilis:** Also known as "liver spots" or solar lentigo; these occur due to chronic UV damage in the elderly.

Q: Hypopigmented patches can be seen in which of the following conditions?

Nevus anemicus. **Explanation:** **Nevus anemicus** is the correct answer because it presents as a congenital, localized **hypopigmented patch**. Unlike other pigmentary disorders, it is not caused by a loss of melanocytes or melanin. Instead, it is a **pharmacological anomaly** where the blood vessels within the patch are hypersensitive to catecholamines, leading to localized vasoconstriction. This reduced blood flow gives the skin a pale/hypopigmented appearance. A key diagnostic feature is that the patch does not redden (erythema) upon rubbing or heat application. **Analysis of Incorrect Options:** * **Becker Nevus:** This is a **hyperpigmented** (dark), hairy hamartomatous patch, typically found on the shoulder or chest of adolescent males. * **Freckles (Ephelides):** These are small, tan-to-brown **hyperpigmented** macules that darken with sun exposure due to increased melanin production (without an increase in melanocyte number). * **Nevus of Ito:** This is a dermal melanocytosis presenting as a bluish-grey **hyperpigmented** patch, typically involving the distribution of the posterior supraclavicular and lateral cutaneous brachial nerves (shoulder/scapular area). **High-Yield Clinical Pearls for NEET-PG:** * **Diascopy Test:** In Nevus anemicus, pressing a glass slide over the border makes the lesion indistinguishable from the surrounding blanched skin. * **Differential Diagnosis:** Must be distinguished from **Nevus depigmentosus** (where melanin is actually decreased) and **Vitiligo** (where melanocytes are absent). * **Association:** Nevus anemicus is frequently associated with **Neurofibromatosis Type 1 (NF-1)** and Phakomatosis pigmentovascularis. * **Wood’s Lamp:** Unlike Vitiligo, Nevus anemicus does not show enhancement under Wood’s lamp because the pigment levels are technically normal.

Q: A female developed a brown macule on the cheek, forehead, and nose after exposure to light following delivery of a baby. What is the diagnosis?

Chloasma. **Explanation:** The clinical presentation describes **Chloasma** (also known as Melasma), a common acquired hypermelanosis. The diagnosis is based on the classic triad of triggers: **female gender, hormonal changes (post-delivery/pregnancy), and UV light exposure.** **Why Chloasma is correct:** Chloasma typically presents as symmetrical, ill-defined brown macules and patches on sun-exposed areas of the face (malar region, forehead, and bridge of the nose). It is often referred to as the "mask of pregnancy" due to the stimulatory effect of estrogen, progesterone, and melanocyte-stimulating hormone (MSH) on melanocytes. Ultraviolet (UV) radiation further exacerbates the condition by inducing lipid peroxidation and melanogenesis. **Why other options are incorrect:** * **SLE:** While SLE presents with a "malar rash," it is typically an erythematous (red), inflammatory, fixed rash that spares the nasolabial folds. It is not a simple brown pigmentary macule. * **Photodermatitis:** This is an inflammatory skin reaction (eczematous or polymorphic) to sunlight. It usually presents with itching, redness, or vesicles rather than stable brown pigmentation. * **Acne Rosacea:** This presents with flushing, persistent erythema, telangiectasia, and papulopustules. It lacks the primary hyperpigmentation characteristic of Chloasma. **NEET-PG High-Yield Pearls:** * **Patterns:** Malar (most common), Centrofacial, and Mandibular. * **Wood’s Lamp Examination:** Used to determine the depth of pigment. **Epidermal** type enhances under Wood's lamp (better prognosis), while **Dermal** type does not. * **Treatment:** The gold standard is **Kligman’s Formula** (Triple Combination Therapy): Hydroquinone (depigmentation), Tretinoin (exfoliation), and a mild Corticosteroid (anti-inflammatory). * **Prevention:** Strict photoprotection (broad-spectrum sunscreen) is the most critical step in management.

Q: A 20-year-old patient presents with a non-progressive hypopigmented lesion on the trunk. On Wood's lamp examination, there is white accentuation. Diascopy is negative. What is the most likely diagnosis?

Nevus depigmentosus. ***Nevus depigmentosus*** - This disorder is a congenital, non-progressive **hypopigmentation** (reduced melanin), which remains constant in size and shape, fitting the clinical scenario. - The lesion shows accentuation (brighter white) under **Wood's lamp**, confirming reduced melanin, and **diascopy is negative** as it is a pigmentary, not vascular, change. *Vitiligo* - Vitiligo is characterized by complete **depigmentation** (leukoderma) due to melanocyte destruction, leading to a stark, **chalk-white** appearance under Wood's lamp. - It is typically a **progressive** symmetrical condition, unlike the static, non-progressive lesion described. *Nevus anemicus* - This is a vascular lesion caused by local exquisite sensitivity to catecholamines, causing **localized vasoconstriction**; hence it is not a true pigment disorder. - The defining feature is a **positive diascopy** (the patch disappears when blanched), which contradicts the negative diascopy in the patient. *Indeterminate leprosy* - Leprosy lesions are hypopigmented patches, but the essential diagnostic criterion is **impaired sensation** (anesthesia or hypoaesthesia), a feature absent from the description. - These patches usually do not show the distinct **white accentuation** seen under Wood's lamp typical of true pigmentary nevi.

Q: A 13-year-old boy presents with patchy depigmented skin on the right flank and upper thigh in segmental distribution, as shown in the image. The depigmentation started 1 year back but has been static for last 4 months. Mother reports use of topical steroids which was ineffective. Diagnosis is?

Segmental vitiligo. ***Segmental vitiligo*** - The presentation of **depigmented skin** in a **segmental distribution** on one side of the body, starting in childhood at 13 years old, is characteristic of **segmental vitiligo**. - Its **static nature** for four months, unlike progressive widespread vitiligo, and **ineffectiveness of topical steroids** further support this diagnosis. *Piebaldism* - Characterized by a **congenital absence of melanocytes** in affected areas, typically presenting at birth with a **white forelock** and symmetrically distributed patches. - Unlike the described case, piebaldism is **stable throughout life** and does not usually appear at 12 years of age or show a segmental pattern extending along dermatomes. *Hypomelanosis of Ito* - This condition is characterized by **streaky or whorled hypopigmentation** following **Blaschko's lines**, often associated with **neurological, skeletal, or ocular abnormalities**. - While it presents in early childhood in a linear or segmental pattern, the lesions are **hypopigmented (lighter than surrounding skin)**, not completely depigmented like in the clinical image, and its lesions are usually static or mildly progressive which isn't completely consistent *Hypopigmented streaks* - This is a descriptive term rather than a specific diagnosis, and while the lesions might appear streaky, the term doesn't encompass the **complete depigmentation**, **segmental distribution**, and **onset characteristics** detailed in the case. - The term "hypopigmented" refers to *reduced* pigmentation, whereas the image and description suggest *complete absence* of pigment, which is depigmentation.

Q: An 18-year-old female presents with hypo-pigmented patches on the dorsal aspect of the foot. Which of the following drugs should not be used in the treatment of this patient? (AIIMS May 2016)

Isotretinoin. ***Isotretinoin*** - Isotretinoin is a retinoid primarily used for severe **acne vulgaris** and does not have a role in the treatment of post-inflammatory hypopigmentation or vitiligo. - Its mechanism of action involves reducing sebaceous gland size and sebum production, which is unrelated to melanin synthesis or pigment regulation. *Topical tacrolimus* - Topical tacrolimus is a **calcineurin inhibitor** commonly used off-label for **vitiligo**, which can present as hypopigmented patches, especially on sensitive skin areas. - It works by modulating the immune response in the skin, which can help in repigmentation. *Clobetasol* - Clobetasol is a **high-potency topical corticosteroid** often used in regimens for **vitiligo** or other inflammatory dermatoses leading to hypopigmentation. - It helps by suppressing local immune activity that may be contributing to melanocyte destruction or dysfunction. *PUVA* - **Psoralen plus ultraviolet A (PUVA)** is a form of **phototherapy** widely used for generalized vitiligo. - Psoralen sensitizes the skin to UVA light, stimulating melanocytes to produce pigment.

Q: The given image shows:

Xeroderma Pigmentosum. ***Xeroderma Pigmentosum*** - The image exhibits severe **photosensitivity** with extensive **erythema**, **scaling**, and numerous **non-melanoma skin cancers** (e.g., basal cell carcinoma, squamous cell carcinoma) on sun-exposed areas, particularly the face. - This condition is characterized by a defect in **DNA repair mechanisms**, leading to extreme vulnerability to UV radiation and a high risk of skin malignancies. *Piebaldism* - Characterized by localized **congenital absence of melanocytes**, resulting in patches of **white skin** and a **white forelock**. - It does not involve sun sensitivity or the development of multiple skin cancers as seen in the image. *Oculo-cutaneous albinism* - This condition involves a generalized reduction or absence of melanin, leading to **pale skin**, **white hair**, and **light-colored eyes**. - While individuals with albinism are photosensitive and at increased risk of skin cancers, the severe, widespread actinic damage and multiple open lesions on the face are more typical of the extreme UV sensitivity seen in xeroderma pigmentosum. *Waardenburg syndrome* - A genetic disorder characterized by varying degrees of **hearing loss**, unusual **eye color** (often brilliant blue or heterochromia), and often a **white forelock**. - It does not primarily involve severe sun sensitivity, extensive actinic damage, or multiple skin cancers as the prominent features.

Q: The image shows presence of:

Piebaldism. ***Piebaldism*** - The image on the right clearly depicts a man with a **white forelock** (poliosis) and **blue irises**, which are characteristic features of **piebaldism**, a rare autosomal dominant genetic disorder. - Piebaldism is characterized by congenital localized areas of **hypopigmentation** due to the absence of melanocytes, commonly affecting the forehead, trunk, and limbs symmetrically. *Vitiligo* - The image on the left, labeled 'a' as Vitiligo, shows **irregular, acquired depigmented patches** on the trunk, which are typically progressive and can appear anywhere on the body. - Although both conditions involve depigmentation, vitiligo is **acquired** and progressive, and usually lacks the distinct congenital features like a white forelock and specific distribution seen in piebaldism. *Xeroderma pigmentosum* - This is a rare genetic disorder characterized by an extreme sensitivity to **ultraviolet (UV) light** due to defects in DNA repair, leading to severe photosensitivity and a very high risk of skin cancers. - It does not primarily present with localized congenital depigmentation or a white forelock. *Incontinentia pigmenti* - This is an X-linked dominant disorder primarily affecting the skin, presenting with various stages of lesions from vesicular to verrucous and hyperpigmented streaks that typically follow **Blaschko's lines**. - It is not characterized by the congenital patches of depigmentation, white forelock, or ocular abnormalities seen in the presented images; rather, it often involves changes in pigmentation that appear swirled or linear.

Q: The image shows presence of:

Becker's nevus. ***Becker's nevus*** - This image shows a **large, irregular, hyperpigmented patch** on the anterior trunk, which may also be **hypertrichotic** (hairy), a classic presentation of Becker's nevus. - Becker's nevus typically appears in males during **adolescence** and is often found on the **shoulder or upper trunk**. *Nevus of Ota* - **Nevus of Ota** is a **pigmented lesion** characterized by blue-gray patches typically found on the **face**, involving the **ophthalmic and maxillary divisions of the trigeminal nerve**. - It does not present as a large, often hairy, hyperpigmented patch on the trunk. *Nevus spilus* - **Nevus spilus** is a **light brown patch** (macule) with multiple **darker brown or black papules or macules** superimposed within it. - The image does not show superimposed darker lesions within a lighter background. *Giant melanocytic nevus of face* - A **giant melanocytic nevus** is a congenital nevus that is typically **present at birth** and covers a large area, often with varied textures and colors, but the question specifies "**of face**" which is not depicted in the image (the lesion is on the trunk). - The lesion in the image is more consistent with a nevus that *develops* in adolescence, rather than a congenital giant nevus of the face.

Q: The image shows presence of:

Lentiginosis. ***Lentiginosis*** - The image displays numerous **dark brown to black macules and patches** scattered over the trunk and neck, which are characteristic of lentigines. - **Lentiginosis** refers to the presence of multiple lentigines, which are benign pigmented lesions resulting from an increased number of melanocytes at the dermal-epidermal junction. *Freckles* - **Freckles** (ephelides) are typically smaller, lighter brown, and increase in number and darkness with sun exposure, often fading in winter. - They are due to increased melanin production by a normal number of melanocytes, unlike lentigines which involve an increase in melanocyte number. *Shagreen patch* - A **shagreen patch** is an irregular, raised, textured area of skin, often found on the lower back, and is typically associated with tuberous sclerosis. - It is a **flesh-colored or hyperpigmented lesion with a leathery texture**, not diffuse small macules as seen in the image. *Congenital nevus* - A **congenital nevus** (birthmark) is usually present at birth or appears shortly after, and can vary in size and color, but typically presents as one or a few localized lesions. - The image shows **widespread, multiple, discrete pigmented lesions** rather than a single or few larger congenital nevi.

Question 1

Which of the following is the reason for the development of a simple lentigo?

Accepted Answer

Increased melanocytes

Answer

Increased melanin

Answer

Increased melanosomes

Answer

All of the above

Question 2

Hypopigmented patches can be seen in which of the following conditions?

Accepted Answer

Nevus anemicus

Answer

Becker nevus

Answer

Freckles

Answer

Nevus of Ito

Question 3

A female developed a brown macule on the cheek, forehead, and nose after exposure to light following delivery of a baby. What is the diagnosis?

Accepted Answer

Chloasma

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Photodermatitis

Answer

Acne rosacea

Question 4

A 20-year-old patient presents with a non-progressive hypopigmented lesion on the trunk. On Wood's lamp examination, there is white accentuation. Diascopy is negative. What is the most likely diagnosis?

Accepted Answer

Nevus depigmentosus

Answer

Nevus anemicus

Answer

Indeterminate leprosy

Answer

Vitiligo

Question 5

A 13-year-old boy presents with patchy depigmented skin on the right flank and upper thigh in segmental distribution, as shown in the image. The depigmentation started 1 year back but has been static for last 4 months. Mother reports use of topical steroids which was ineffective. Diagnosis is?

Accepted Answer

Segmental vitiligo

Answer

Piebaldism

Answer

Hypomelanosis of Ito

Answer

Hypopigmented streaks

Question 6

An 18-year-old female presents with hypo-pigmented patches on the dorsal aspect of the foot. Which of the following drugs should not be used in the treatment of this patient? (AIIMS May 2016)

Accepted Answer

Isotretinoin

Answer

Topical tacrolimus

Answer

Clobetasol

Answer

PUVA

Question 7

The given image shows:

Accepted Answer

Xeroderma Pigmentosum

Answer

Piebaldism

Answer

Oculo-cutaneous albinism

Answer

Waardenburg syndrome

Question 8

The image shows presence of:

Accepted Answer

Piebaldism

Answer

Vitiligo

Answer

Xeroderma pigmentosum

Answer

Incontinentia pigmenti

Question 9

The image shows presence of:

Accepted Answer

Becker's nevus

Answer

Nevus of Ota

Answer

Nevus spilus

Answer

Giant melanocytic nevus of face

Question 10

The image shows presence of:

Accepted Answer

Lentiginosis

Answer

Freckles

Answer

Shagreen patch

Answer

Congenital nevus

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

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