Pigmentary Disorders Practice Questions

Q: A child presents with a hyperpigmented patch over the back since birth. The level of melanin in this patch on biopsy is likely to be?

Deep dermis. ### Explanation The clinical presentation describes a **Mongolian spot** (Congenital Dermal Melanocytosis), which is the most common hyperpigmented patch present at birth, typically located over the lumbosacral area or back. **1. Why the Correct Answer is Right:** The underlying mechanism is the **arrest of melanocyte migration**. During embryogenesis, melanocytes migrate from the neural crest to the epidermis. In certain conditions, these melanocytes fail to reach the epidermis and remain trapped in the **deep dermis**. Because these melanocytes are located deep within the skin, the light reflecting off them undergoes the **Tyndall effect**, giving the lesion its characteristic slate-gray or blue-black appearance. **2. Why Other Options are Wrong:** * **Epidermal:** Melanin in the epidermis (e.g., freckles, lentigines) appears brown. If the pigment were here, the lesion would not have the characteristic bluish hue of a congenital dermal melanocytosis. * **Dermoepidermal Junction:** This is the site of melanocyte activity in junctional nevi. Pigment here typically appears dark brown to black. * **Superficial Dermis:** While some dermal melanocytoses (like Nevus of Ito or Ota) involve the upper and mid-dermis, the classic "Mongolian spot" and deep blue nevi are characterized by melanocytes residing specifically in the **deep reticular dermis**. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mongolian Spot:** Most common in Asians; usually fades by age 2–5 years; no treatment required. * **Nevus of Ota:** Dermal melanocytosis along the ophthalmic and maxillary branches of the **Trigeminal nerve** (unilateral facial pigmentation). * **Nevus of Ito:** Similar to Ota but involves the **posterior shoulder** (acromioclavicular area). * **Tyndall Effect:** Shorter wavelengths (blue) are scattered more by dermal melanin, while longer wavelengths (red) are absorbed, explaining why deep pigment looks blue.

Q: Psoralen-A is used in the treatment of:

Vitiligo. **Explanation:** **Vitiligo** is the correct answer because Psoralens (such as 8-Methoxypsoralen or Trimethylpsoralen) are the mainstay of **PUVA therapy** (Psoralen + Ultraviolet A). Psoralens are photosensitizing agents that, when activated by UVA light, stimulate melanocyte proliferation and migration from the hair follicle reservoir to the depigmented skin, leading to repigmentation. **Analysis of Options:** * **Pemphigus:** This is an autoimmune blistering disorder treated primarily with systemic corticosteroids and immunosuppressants (e.g., Azathioprine, Rituximab). Phototherapy is generally avoided as it can occasionally trigger flares. * **Pityriasis alba:** This is a mild form of eczematous dermatitis characterized by hypopigmented patches, usually in children. It is self-limiting and treated with emollients or low-potency topical steroids, not systemic phototherapy. * **Ichthyosis:** This refers to a group of genetic keratinization disorders (e.g., Ichthyosis vulgaris). Treatment focuses on keratolytics (salicylic acid), emollients, and oral retinoids (Acitretin), rather than psoralens. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Psoralens intercalate into DNA; upon UVA exposure, they form DNA adducts (monoadducts and cross-links), inhibiting DNA synthesis and modulating the local immune response. * **PUVA vs. NBUVB:** While PUVA was the gold standard, **Narrowband UVB (311 nm)** is now the first-line phototherapy for vitiligo due to its better safety profile and lack of need for systemic psoralens. * **Side Effects:** Acute side effects of PUVA include nausea, erythema (burns), and pruritus. Long-term risks include premature skin aging and an increased risk of Non-Melanoma Skin Cancer (NMSC).

Q: A 39-year-old woman presents with a thickened, hyperpigmented, velvety lesion over the axillae. This condition is associated with which of the following?

Insulin resistance. ### Explanation The clinical presentation of **thickened, hyperpigmented, velvety lesions** in intertriginous areas like the axillae and neck is the hallmark of **Acanthosis Nigricans (AN)**. **Why Insulin Resistance is Correct:** The primary underlying mechanism for benign AN is **hyperinsulinemia** associated with **Insulin Resistance**. High levels of circulating insulin cross-react with **Insulin-like Growth Factor-1 (IGF-1) receptors** on keratinocytes and dermal fibroblasts. This stimulates cellular proliferation, leading to the characteristic epidermal thickening (acanthosis) and velvety texture. It is commonly seen in Type 2 Diabetes Mellitus, PCOS, and obesity. **Why Other Options are Incorrect:** * **A. Frequent wearing of velvet clothes:** This is a distractor. The term "velvety" describes the clinical texture of the skin due to papillomatosis and acanthosis; it is not caused by external fabric contact. * **B. Systemic lupus erythematosus (SLE):** SLE typically presents with photosensitive rashes (malar rash) or discoid plaques, not velvety hyperpigmentation. * **C. Tuberculosis:** While some dermatological conditions like Lupus Vulgaris are associated with TB, Acanthosis Nigricans has no direct etiologic link to mycobacterial infections. **High-Yield Clinical Pearls for NEET-PG:** * **Malignant Acanthosis Nigricans:** If AN appears suddenly, is very extensive, or involves the palms ("Tripe palms") and oral mucosa, it is highly suggestive of an internal malignancy, most commonly **Gastric Adenocarcinoma**. * **Common Sites:** Posterior neck (most common), axillae, groin, and knuckles. * **Histopathology:** Shows hyperkeratosis and papillomatosis. Interestingly, despite the dark appearance, there is minimal increase in melanocytes; the color is due to the thickened epidermis. * **Drug-induced AN:** Can be caused by Nicotinic acid, systemic corticosteroids, and OCPs.

Q: A female presents with hypopigmented lesions on the central forehead. Which drug is responsible?

Para tertiary butyl phenol. **Explanation:** The correct answer is **Para tertiary butyl phenol (PTBP)**. This condition is known as **Chemical Leucoderma** (or Contact Vitiligo). **Why PTBP is correct:** PTBP is a common antioxidant and adhesive used in the manufacturing of **bindis**, rubber, and adhesives. In the Indian context, "Bindi-induced depigmentation" is a classic clinical presentation. PTBP acts as a potent melanocytotoxin; it is structurally similar to tyrosine and competes for the enzyme tyrosinase, leading to the selective destruction of melanocytes and subsequent hypopigmented or depigmented patches at the site of contact (typically the central forehead). **Analysis of Incorrect Options:** * **A. Hydroquinone:** Primarily used as a skin-lightening agent for melasma. While it can cause "confetti-like" depigmentation if used in high concentrations, it is not the primary cause of bindi-induced leucoderma. * **B. Ether metabolite of hydroquinone (Monobenzyl ether of hydroquinone):** This is a potent permanent depigmenting agent used to treat extensive vitiligo (depigmentation therapy). It causes systemic depigmentation, not localized bindi-pattern lesions. * **C. Para tertiary butyl catechol:** Used in the production of resins and plastics. While it can cause chemical leucoderma, it is less commonly associated with bindi adhesives compared to PTBP. **High-Yield Clinical Pearls for NEET-PG:** * **Common Culprits:** PTBP (Bindis), Monobenzyl ether of hydroquinone (Rubber gloves/condoms), and P-phenylenediamine (Hair dyes). * **Clinical Feature:** Unlike Vitiligo, chemical leucoderma often shows "confetti-like" macules at the periphery and lacks the Koebner phenomenon. * **Diagnosis:** Primarily clinical; Patch testing with PTBP (1% in petrolatum) can confirm the sensitivity. * **Treatment:** Immediate cessation of the offending agent; topical steroids or calcineurin inhibitors may help in repigmentation.

Q: A large, dark brown patch is noted on the back. What is the most likely diagnosis?

Becker nevus. ***Becker nevus*** - **Large, dark brown patch** on the back is characteristic of Becker nevus, which typically appears as an **irregular, unilateral pigmented patch** on the **upper trunk** or **shoulder area**. - Often develops during **adolescence** and may be associated with **hypertrichosis** (excessive hair growth) within the lesion, predominantly affecting **males**. *Seborrheic melanosis* - Appears as **multiple, well-demarcated brown patches** with a **"stuck-on" appearance** and **warty surface texture**, unlike the smooth patch described. - More commonly seen in **elderly patients** and typically involves **sun-exposed areas** like the face and chest. *Lichen planus pigmentosus* - Presents as **multiple small, dark brown macules** in a **bilateral symmetric distribution**, not as a single large patch. - Often associated with **mucous membrane involvement** and **nail changes**, which are not mentioned in this case. *Pityriasis versicolor* - Characterized by **multiple small, scaly patches** that are typically **lighter or darker** than surrounding skin with a **fine scale**. - Caused by **Malassezia fungus** and shows **yellow fluorescence** under **Wood's lamp examination**, unlike the single dark patch described.

Q: In an elderly patient, acanthosis nigricans usually indicates what?

Malignancy. **Explanation:** **Acanthosis Nigricans (AN)** is a clinical sign characterized by hyperpigmented, velvety, and verrucous plaques, most commonly involving intertriginous areas like the axilla, neck, and groin. **Why Malignancy is the Correct Answer:** While AN is most commonly associated with insulin resistance and obesity (Pseudo-AN), its sudden onset in an **elderly patient** is a classic "red flag" for **Malignant Acanthosis Nigricans**. This is a paraneoplastic syndrome, most frequently associated with **adenocarcinomas of the gastrointestinal tract** (specifically the stomach in 55-60% of cases). The pathogenesis involves tumor-secreted growth factors, such as Transforming Growth Factor-alpha (TGF-α), which stimulate epidermal keratinocytes and fibroblasts. **Analysis of Incorrect Options:** * **A. A skin disorder:** While AN manifests on the skin, it is primarily a cutaneous marker of an underlying systemic condition (metabolic or neoplastic) rather than a primary skin disease. * **C. Senile brain disease:** There is no established clinical association between AN and neurodegenerative or senile brain diseases. * **D. Individuals of African descent:** While AN is more easily visible or prevalent in darker skin phototypes due to increased melanin, it is not "usually" found exclusively in this group, nor does this explain its clinical significance in an elderly patient. **High-Yield Clinical Pearls for NEET-PG:** * **Tripe Palms:** Rugose, velvety thickening of the palms; often occurs alongside malignant AN. If seen alone, it is highly associated with **lung cancer**; if seen with AN, it points to **gastric cancer**. * **Leser-Trélat Sign:** Sudden eruption of multiple seborrheic keratoses; another paraneoplastic sign often associated with internal malignancy and AN. * **Drug-induced AN:** Can be caused by systemic corticosteroids, nicotinic acid, and oral contraceptives.

Q: A 28-year-old pregnant female presents with complaints of brownish pigmentation on the bridge of her nose and cheeks, noticed after returning from a beach vacation. There is no pain or itching at the affected site. What is your most likely diagnosis?

Chloasma. ### Explanation **Diagnosis: Chloasma (Melasma)** The clinical presentation of symmetric, asymptomatic brownish pigmentation on the bridge of the nose and cheeks (malar distribution) in a pregnant female, exacerbated by sun exposure, is classic for **Chloasma**. 1. **Why Chloasma is correct:** Also known as the "mask of pregnancy," Chloasma is an acquired hypermelanosis. It is driven by hormonal changes (increased estrogen, progesterone, and MSH) and triggered by UV radiation. The absence of itching or pain distinguishes it from inflammatory conditions. 2. **Why other options are incorrect:** * **Photodermatitis:** This typically presents with inflammatory signs like erythema, itching, or scaling following sun exposure, rather than isolated hyperpigmentation. * **Systemic Lupus Erythematosus (SLE):** While SLE features a malar "butterfly" rash, it is typically an erythematous (red), often raised rash that spares the nasolabial folds and is usually accompanied by systemic symptoms (fever, joint pain). * **Acne Rosacea:** This presents with erythema, telangiectasia, papules, and pustules. It is a vascular and inflammatory disorder, not a primary pigmentary one. **High-Yield Clinical Pearls for NEET-PG:** * **Patterns:** Melasma has three clinical patterns: Centrofacial (most common), Malar, and Mandibular. * **Wood’s Lamp Examination:** Used to determine the depth of pigment. **Epidermal** type shows enhancement under Wood's lamp (responds best to treatment), while **Dermal** type does not enhance. * **Treatment:** The gold standard is **Kligman’s Formula** (Triple Combination Therapy): Hydroquinone (lightening agent), Tretinoin (exfoliant), and a Corticosteroid (anti-inflammatory). * **Prevention:** Strict photoprotection (broad-spectrum sunscreens) is the most critical step in management.

Q: LEOPARD syndrome does not include which of the following?

Atrial myxoma. **Explanation:** **LEOPARD syndrome**, also known as **Noonan syndrome with multiple lentigines**, is an autosomal dominant neuro-cardio-facial-cutaneous disorder caused primarily by mutations in the **PTPN11 gene**. The name is a mnemonic representing its characteristic clinical features. **Why Atrial Myxoma is the correct answer:** Atrial myxoma is **not** a component of LEOPARD syndrome. Instead, it is a hallmark of **Carney Complex** (along with spotty skin pigmentation, endocrine overactivity, and schwannomas). In LEOPARD syndrome, the primary cardiac findings are structural and electrical, not neoplastic. **Analysis of incorrect options (Components of LEOPARD):** * **L – Lentigines:** Multiple small, dark brown macules appearing in childhood. * **E – ECG abnormalities:** Most commonly bundle branch blocks or ventricular hypertrophy. * **O – Ocular hypertelorism:** Widely spaced eyes. * **P – Pulmonary stenosis:** A common structural heart defect in these patients (though hypertrophic cardiomyopathy is actually more frequent). * **A – Abnormalities of genitalia:** Such as cryptorchidism or hypospadias. * **R – Retardation of growth:** Patients often exhibit short stature. * **D – Deafness:** Specifically sensorineural hearing loss. **Clinical Pearls for NEET-PG:** * **Mnemonic Check:** If a question asks about "Multiple Lentigines" + "Heart defects," think LEOPARD. * **Genetics:** PTPN11 mutation (seen in ~80% of cases), similar to Noonan syndrome. * **Differential Diagnosis:** Do not confuse with **NAME/LAMB syndrome** (variants of Carney Complex), which specifically feature atrial myxomas. * **Most Common Cardiac Finding:** While 'P' stands for Pulmonary Stenosis, **Hypertrophic Cardiomyopathy** is the most common cardiac abnormality in LEOPARD syndrome.

Q: A 19-year-old girl presents with light brown pigmentation over the malar eminence. What is the likely diagnosis?

Melasma. ### Explanation **Correct Answer: C. Melasma** **Clinical Reasoning:** Melasma is a common acquired hypermelanosis characterized by symmetrical, light-to-dark brown macules and patches with irregular borders. It typically affects sun-exposed areas of the face, most commonly the **malar eminence** (cheeks), forehead, and upper lip. It is significantly more common in females of reproductive age and is exacerbated by UV radiation and hormonal influences (estrogen/progesterone). **Why other options are incorrect:** * **A. Chloasma:** While often used interchangeably with melasma, "chloasma" specifically refers to the "mask of pregnancy." Since the question does not specify pregnancy, **Melasma** is the more accurate, general clinical term. * **B. Systemic Lupus Erythematosus (SLE):** SLE presents with a "malar rash" (butterfly rash), but this is typically **erythematous** (red), inflammatory, and often spares the nasolabial folds. It is not a primary pigmentary disorder. * **D. Melanoma:** This is a malignant neoplasm of melanocytes. It typically presents as an asymmetrical, variegated, enlarging nodule or plaque with irregular borders (ABCDE criteria), rather than diffuse macular pigmentation over the malar area. **High-Yield Pearls for NEET-PG:** * **Patterns of Melasma:** Centrofacial (most common), Malar, and Mandibular. * **Wood’s Lamp Examination:** Used to determine the depth of pigment. * *Epidermal:* Pigment becomes more prominent. * *Dermal:* Pigment becomes less prominent. * **First-line Treatment:** Kligman’s Formula (Triple Combination Therapy): Hydroquinone + Tretinoin + Topical Steroid (e.g., Fluocinolone acetonide). * **Histopathology:** Shows increased melanin in the epidermis/dermis and solar elastosis.

Question 1

A child presents with a hyperpigmented patch over the back since birth. The level of melanin in this patch on biopsy is likely to be?

Accepted Answer

Deep dermis

Answer

Epidermal

Answer

Dermoepidermal junction

Answer

Superficial dermis

Question 2

A newborn child presents with a solitary white well-defined hypopigmented patch on their right thigh. What is the diagnosis?

Accepted Answer

Nevus achromicus

Answer

Piebaldism

Answer

Albinism

Answer

Acral vitiligo

Question 3

Psoralen-A is used in the treatment of:

Accepted Answer

Vitiligo

Answer

Pemphigus

Answer

Pityriasis alba

Answer

Ichthyosis

Question 4

A 39-year-old woman presents with a thickened, hyperpigmented, velvety lesion over the axillae. This condition is associated with which of the following?

Accepted Answer

Insulin resistance

Answer

Frequent wearing of velvet clothes

Answer

Systemic lupus erythematosus (SLE)

Answer

Tuberculosis

Question 5

A female presents with hypopigmented lesions on the central forehead. Which drug is responsible?

Accepted Answer

Para tertiary butyl phenol

Answer

Hydroquinone

Answer

Ether metabolite of hydroquinone

Answer

Para tertiary butyl catechol

Question 6

A large, dark brown patch is noted on the back. What is the most likely diagnosis?

Accepted Answer

Becker nevus

Answer

Seborrheic melanosis

Answer

Lichen planus pigmentosus

Answer

Pityriasis versicolor

Question 7

In an elderly patient, acanthosis nigricans usually indicates what?

Accepted Answer

Malignancy

Answer

A skin disorder

Answer

Senile brain disease

Answer

It is usually found in individuals of African descent

Question 8

A 28-year-old pregnant female presents with complaints of brownish pigmentation on the bridge of her nose and cheeks, noticed after returning from a beach vacation. There is no pain or itching at the affected site. What is your most likely diagnosis?

Accepted Answer

Chloasma

Answer

Photodermatitis

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Acne rosacea

Question 9

LEOPARD syndrome does not include which of the following?

Accepted Answer

Atrial myxoma

Answer

Growth retardation

Answer

ECG abnormalities

Answer

Pulmonary stenosis

Question 10

A 19-year-old girl presents with light brown pigmentation over the malar eminence. What is the likely diagnosis?

Accepted Answer

Melasma

Answer

Chloasma

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Melanoma

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

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