Pigmentary Disorders Practice Questions

Q: A 23-year-old college student has asymptomatic and hyperpigmented macules on both palms for three weeks. What is the most appropriate diagnostic test?

Veneral Diseases Research Laboratory (VDRL) test. ### Explanation The clinical presentation of asymptomatic, hyperpigmented macules on the palms (and often soles) in a young adult is a classic hallmark of **Secondary Syphilis**. **1. Why VDRL is the correct answer:** Secondary syphilis is known as the "Great Imitator," but its predilection for the palms and soles is a highly specific diagnostic clue. The lesions typically appear as copper-colored, non-pruritic maculopapular eruptions. Since syphilis is a systemic infection caused by *Treponema pallidum*, the initial screening test of choice is a non-treponemal test like the **VDRL** or **RPR (Rapid Plasma Reagin)**. A positive result would then be confirmed with treponemal-specific tests (e.g., TPHA or FTA-ABS). **2. Why other options are incorrect:** * **Skin Biopsy:** While it might show plasma cell infiltration, it is not the first-line diagnostic test for suspected syphilis when serology is readily available and non-invasive. * **Serum Cortisol:** Low cortisol (Addison’s disease) causes generalized hyperpigmentation, particularly in creases and pressure points, but does not typically present as isolated macules on the palms. * **Arsenic Assay:** Chronic arsenic poisoning causes "raindrop" pigmentation on the trunk and "punctate keratosis" (hard thickening) on the palms/soles, rather than simple asymptomatic macules. **3. Clinical Pearls for NEET-PG:** * **The "Money" Sign:** Palmar and plantar lesions in a young, sexually active patient should always trigger a suspicion of Secondary Syphilis. * **Other features of Secondary Syphilis:** Generalized lymphadenopathy (epitrochlear nodes), Condyloma lata (moist perineal warts), and "moth-eaten" alopecia. * **Differential Diagnosis:** For palmar macules, consider Erythema Multiforme (target lesions) and Hand-Foot-Mouth Disease (vesicles). * **Treatment:** The gold standard remains **Benzathine Penicillin G** (2.4 million units IM, single dose).

Q: Diffuse hyperpigmentation is seen in all except?

Phenylketonuria. **Explanation:** The correct answer is **Phenylketonuria (PKU)** because it is characterized by **hypopigmentation**, not hyperpigmentation. **1. Why Phenylketonuria (PKU) is the correct answer:** PKU is an autosomal recessive disorder caused by a deficiency of the enzyme **phenylalanine hydroxylase**. This leads to an accumulation of phenylalanine and a deficiency of **tyrosine**. Since tyrosine is the essential precursor for melanin synthesis (via the enzyme tyrosinase), patients with PKU exhibit generalized hypopigmentation of the skin, blonde hair, and blue eyes. **2. Analysis of Incorrect Options (Causes of Diffuse Hyperpigmentation):** * **Addison’s Disease:** Low cortisol leads to a compensatory increase in **ACTH** (Adrenocorticotropic hormone). ACTH shares a common precursor with **MSH** (Melanocyte-stimulating hormone); hence, high levels stimulate melanocytes, causing diffuse hyperpigmentation, especially in palmar creases and buccal mucosa. * **Cushing’s Syndrome:** Specifically in **ACTH-dependent** Cushing’s (like Cushing’s disease or ectopic ACTH secretion), the excess ACTH leads to hyperpigmentation via the same mechanism as Addison’s. * **Porphyria Cutanea Tarda (PCT):** This condition causes skin fragility and blistering in sun-exposed areas. Chronic sun exposure in PCT patients, combined with iron overload, often results in diffuse hyperpigmentation and hypertrichosis (excess hair growth). **Clinical Pearls for NEET-PG:** * **Mnemonic for PKU:** **P**ale skin, **P**henylalanine hydroxylase deficiency, **P**sychotic/Intellectual disability, **P**eculiar "mousy" odor. * **Other causes of diffuse hyperpigmentation:** Vitamin B12 deficiency, Hemochromatosis ("Bronze diabetes"), and drugs like Busulfan or Clofazimine. * **Key distinction:** In Addison’s, hyperpigmentation is a hallmark; in Cushing’s, it only occurs if ACTH is elevated (not in adrenal tumors).

Q: A 30-year-old female presents with light brown lesions involving both her cheeks. The lesions have never been erythematous. Which of the following is the most probable diagnosis?

Chloasma. ### Explanation **Correct Option: B. Chloasma (Melasma)** Chloasma, commonly known as melasma, is an acquired hypermelanosis characterized by symmetric, light-to-dark brown macules and patches on sun-exposed areas, most frequently the cheeks, forehead, and upper lip. * **Key Clinical Feature:** The hallmark of chloasma is that it is a **non-inflammatory** pigmentary disorder. The question specifies that the lesions have "never been erythematous," which points directly toward a primary pigmentary process rather than a post-inflammatory one. It is most common in women of reproductive age and is often associated with hormonal changes (pregnancy, OCPs) and UV exposure. **Why other options are incorrect:** * **A. Systemic Lupus Erythematosus (SLE):** The classic malar rash of SLE is typically **erythematous** (red), edematous, and may be painful or pruritic. It often spares the nasolabial folds, unlike the diffuse pigmentation of chloasma. * **C. Airborne Contact Dermatitis:** This is an inflammatory condition. It presents with **erythema**, scaling, and itching in the initial stages. Chronic cases may show lichenification, but the absence of a preceding red/itchy phase rules it out. * **D. Photosensitive Reaction:** These reactions (like phototoxic or photoallergic dermatitis) typically present with **erythema**, burning, or vesiculation immediately following sun exposure. **NEET-PG High-Yield Pearls:** * **Wood’s Lamp Examination:** Used to determine the depth of melanin. **Epidermal** type shows enhancement under Wood’s lamp, while **Dermal** type does not. * **Treatment Gold Standard:** Kligman’s Formula (Triple Combination Therapy): Hydroquinone + Tretinoin + Topical Steroid. * **Differential:** Unlike SLE, Chloasma often involves the nasolabial folds and lacks systemic symptoms (fever, joint pain).

Q: Acanthosis nigricans is commonly associated with which of the following conditions?

All of the above. **Explanation:** Acanthosis Nigricans (AN) is a clinical marker characterized by hyperpigmented, velvety plaques typically found in intertriginous areas like the neck and axilla. The underlying pathophysiology involves the stimulation of **Insulin-like Growth Factor (IGF) receptors** on keratinocytes and fibroblasts, leading to epidermal proliferation. * **Diabetes Mellitus (Option A):** This is the most common association. Hyperinsulinemia (seen in Type 2 DM and Obesity) causes excess insulin to bind to IGF-1 receptors, triggering the characteristic skin changes. * **Gastrointestinal Cancers (Option B):** This represents **Malignant Acanthosis Nigricans**. It is a paraneoplastic syndrome most commonly associated with **Gastric Adenocarcinoma**. It is usually sudden in onset, extensive, and involves the palms (tripe palms) or mucous membranes. * **Hypothyroidism (Option C):** AN is frequently associated with various endocrinopathies, including hypothyroidism, PCOS, and Cushing’s syndrome, due to metabolic disturbances and insulin resistance. Since AN can be a manifestation of metabolic, endocrine, or malignant processes, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **Tripe Palms:** Rugose thickening of the palms; highly suggestive of internal malignancy (usually lung or gastric). 2. **Sign of Leser-Trélat:** Sudden eruption of multiple seborrheic keratoses; often co-exists with malignant AN. 3. **Drug-induced AN:** Can be caused by systemic corticosteroids, nicotinic acid, and oral contraceptives. 4. **Histopathology:** Shows hyperkeratosis and papillomatosis; surprisingly, "acanthosis" (thickening of the stratum spinosum) is often minimal despite the name.

Q: Which of the following is not a ceruloderma?

Cockade nevus. **Explanation:** The term **Ceruloderma** (from the Greek *kyaneos* meaning blue) refers to conditions characterized by a **blue-gray skin discoloration**. This occurs due to the **Tyndall effect**, where shorter wavelengths of light (blue) are scattered by melanin pigment located deep within the dermis, while longer wavelengths (red) are absorbed. **Why Cockade Nevus is the correct answer:** A **Cockade nevus** (also known as Nevus en cocarde) is a rare variant of a melanocytic nevus that resembles a target or rosette. It consists of a central pigmented nevus surrounded by a depigmented halo, which is then encircled by a peripheral ring of hyperpigmentation. Unlike cerulodermas, the pigment in a Cockade nevus is located in the **epidermis or dermo-epidermal junction**, resulting in a **brown** appearance rather than blue. **Analysis of incorrect options (Dermal Melanocytoses):** * **Nevus of Ota:** A dermal melanocytosis involving the distribution of the first and second divisions of the **trigeminal nerve**. It typically presents as a blue-gray patch on the face and often involves the sclera. * **Nevus of Ito:** Similar to Nevus of Ota but involves the distribution of the **posterior supraclavicular and lateral cutaneous brachial nerves** (shoulder, side of neck, and scapular area). * **Mongolian spot:** A congenital blue-gray patch usually found in the **lumbosacral region**. It is caused by the failure of melanocytes to migrate from the neural crest to the epidermis, leaving them trapped in the dermis. **High-Yield Pearls for NEET-PG:** * **Tyndall Effect:** Deep melanin = Blue; Superficial melanin = Brown. * **Nevus of Ota:** Most common in Asians; 10% risk of glaucoma; requires periodic intraocular pressure monitoring. * **Blue Nevus:** Another classic example of ceruloderma (dermal melanocytes). * **Mongolian Spots:** Most commonly resolve spontaneously by age 3–5 years.

Q: Decrease in the number of melanocytes is seen in which of the following conditions?

Piebaldism. **Explanation:** The core concept in pigmentary disorders is distinguishing between a **functional defect** (normal melanocyte count, abnormal melanin production) and a **structural defect** (absence or decrease in the number of melanocytes). **Why Piebaldism is correct:** Piebaldism is an autosomal dominant condition caused by a mutation in the **c-kit proto-oncogene**, which is essential for the migration and survival of melanoblasts. Due to defective migration from the neural crest to the skin during embryogenesis, there is a localized **absence or decrease in the number of melanocytes** in the affected patches. Clinically, it presents as a stable, congenital white forelock and symmetrical depigmented patches on the forehead, trunk, and extremities. **Analysis of Incorrect Options:** * **Albinism:** This is a disorder of melanin synthesis (usually due to a **tyrosinase enzyme deficiency**). The number of melanocytes is **normal**, but they cannot produce melanin. * **Ichthyosis:** This is a disorder of keratinization characterized by dry, scaly skin. It does not primarily involve a change in melanocyte count. * **Chemical Leucoderma:** This occurs due to exposure to phenolic compounds (like adhesives or rubber). While it can lead to melanocyte destruction, it is an acquired condition. In the context of "decrease in number" as a primary pathological hallmark in exams, Piebaldism (congenital absence) is the more classic example. **High-Yield Clinical Pearls for NEET-PG:** * **Vitiligo vs. Piebaldism:** Both show an absence of melanocytes, but Vitiligo is *acquired and progressive*, whereas Piebaldism is *congenital and static*. * **Waardenburg Syndrome:** If Piebaldism is associated with sensorineural deafness and dystopia canthorum, suspect this syndrome. * **Histopathology:** In Albinism, DOPA reaction is negative, but melanocytes are present on silver stains. In Piebaldism/Vitiligo, both are absent.

Q: Café–au–lait spots are not seen in which of the following conditions?

Hyperparathyroidism. **Explanation:** Café–au–lait macules (CALMs) are flat, hyperpigmented birthmarks caused by an increased concentration of melanin and melanocytes in the epidermis. While they can occur sporadically in healthy individuals, multiple CALMs are hallmark features of several neurocutaneous and genetic syndromes. **Why Hyperparathyroidism is the Correct Answer:** Hyperparathyroidism is an endocrine disorder characterized by excess parathyroid hormone, leading to hypercalcemia and bone resorption. It does **not** have a primary cutaneous manifestation involving pigmentary macules like CALMs. It is often confused with **McCune-Albright Syndrome**, which features polyostotic fibrous dysplasia (mimicking bone lesions) and endocrine abnormalities, but the two are distinct entities. **Analysis of Incorrect Options:** * **Neurofibromatosis Type 1 (NF1):** The most common association. Diagnostic criteria require $\geq 6$ CALMs ( $>5$ mm in prepubertal and $>15$ mm in postpubertal individuals). * **McCune-Albright Syndrome:** Characterized by the triad of polyostotic fibrous dysplasia, precocious puberty, and large, unilateral CALMs with irregular "Coast of Maine" borders. * **Bloom Syndrome:** An autosomal recessive chromosomal instability disorder. Along with growth retardation and telangiectatic erythema, CALMs are a recognized clinical feature. **High-Yield Clinical Pearls for NEET-PG:** * **Coast of California:** Smooth borders of CALMs seen in **Neurofibromatosis**. * **Coast of Maine:** Jagged, irregular borders of CALMs seen in **McCune-Albright Syndrome**. * **Crowe Sign:** Axillary or inguinal freckling, a pathognomonic sign for NF1. * **Other Associations:** CALMs are also seen in Fanconi Anemia, Tuberous Sclerosis (rarely), Noonan Syndrome, and Ataxia-Telangiectasia.

Q: Characteristic skin lesion in Peutz-Jeghers syndrome is?

Lentigines. **Explanation:** **Peutz-Jeghers Syndrome (PJS)** is an autosomal dominant disorder characterized by the mutation of the **STK11 (LKB1)** gene. The hallmark clinical features are gastrointestinal hamartomatous polyposis and mucocutaneous pigmentation. **Why Lentigines is the correct answer:** The characteristic lesions in PJS are **melanocytic lentigines**. Unlike common freckles, these are small (1–5 mm), dark brown to blue-black macules that typically appear in early childhood. They are most characteristically found on the **lips (especially the lower lip)**, buccal mucosa, perioral area, and digits. Crucially, mucosal lentigines in PJS do not fade with sun exposure, which distinguishes them from freckles. **Analysis of Incorrect Options:** * **A. Freckles (Ephelides):** These darken with sun exposure and fade in winter. They rarely involve the mucosa, whereas PJS lesions characteristically involve the buccal mucosa. * **C. Cafe au lait spots:** These are larger, "coffee-with-milk" colored macules associated primarily with **Neurofibromatosis Type 1 (NF-1)** and McCune-Albright syndrome. * **D. Adenoma sebaceum:** This is a misnomer for **angiofibromas**, which are firm, skin-colored or reddish papules found in a malar distribution in **Tuberous Sclerosis**. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant; Gene: **STK11** on Chromosome 19p. * **Polyps:** Hamartomatous, most common in the **small intestine** (jejunum). * **Complications:** Intussusception (most common surgical complication) and a significantly increased risk of GI and extra-GI malignancies (e.g., breast, pancreas, ovary). * **Dermatology Tip:** While skin lentigines may fade after puberty, **buccal mucosal pigmentation** usually persists into adulthood, serving as a permanent clinical marker.

Question 1

A 23-year-old college student has asymptomatic and hyperpigmented macules on both palms for three weeks. What is the most appropriate diagnostic test?

Accepted Answer

Veneral Diseases Research Laboratory (VDRL) test

Answer

Skin biopsy

Answer

Serum cortisol levels

Answer

Assay for arsenic in skin, hair & nails

Question 2

Diffuse hyperpigmentation is seen in all except?

Accepted Answer

Phenylketonuria

Answer

Addison's disease

Answer

Cushing's syndrome

Answer

Porphyria cutanea tarda

Question 3

A 30-year-old female presents with light brown lesions involving both her cheeks. The lesions have never been erythematous. Which of the following is the most probable diagnosis?

Accepted Answer

Chloasma

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Airborne contact dermatitis

Answer

Photosensitive reaction

Question 4

Acanthosis nigricans is commonly associated with which of the following conditions?

Accepted Answer

All of the above

Answer

Diabetes mellitus

Answer

Gastrointestinal cancers

Answer

Hypothyroidism

Question 5

Which of the following is not a ceruloderma?

Accepted Answer

Cockade nevus

Answer

Nevus of Ota

Answer

Nevus of Ito

Answer

Mongolian spot

Question 6

Decrease in the number of melanocytes is seen in which of the following conditions?

Accepted Answer

Piebaldism

Answer

Albinism

Answer

Ichthyosis

Answer

Chemical leucoderma

Question 7

Albinism is associated with which of the following?

Accepted Answer

It is associated with platelet abnormalities, especially with aspirin.

Answer

Hair bulb for tyrosine positivity test is useful only when the child is 5 years old.

Answer

Complete decussation is invariable in all albinism.

Answer

It is associated with thrombosis under general anaesthesia.

Question 8

Café–au–lait spots are not seen in which of the following conditions?

Accepted Answer

Hyperparathyroidism

Answer

Neurofibromatosis

Answer

McCune Albright syndrome

Answer

Bloom syndrome

Question 9

Characteristic skin lesion in Peutz-Jeghers syndrome is?

Accepted Answer

Lentigines

Answer

Freckles

Answer

Cafe au lait spots

Answer

Adenoma sebaceum

Question 10

A 25-year-old man presents with pigmented macules on his palms, soles, and oral mucosa. He also has anemia and abdominal pain. What is the most likely diagnosis?

Accepted Answer

Peutz-Jeghers Syndrome

Answer

Cushing's syndrome

Answer

Albright's syndrome

Answer

Incontinentia pigmenti

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

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