Pigmentary Disorders Practice Questions

Q: Cafe-au-lait spots on the skin are characteristic of which of the following conditions?

Von Recklinghausen disease. **Explanation:** **1. Why Von Recklinghausen Disease is Correct:** Von Recklinghausen disease, also known as **Neurofibromatosis Type 1 (NF1)**, is an autosomal dominant neurocutaneous syndrome. **Café-au-lait macules (CALMs)** are the earliest clinical sign of NF1, appearing in infancy. These are well-circumscribed, "coffee-with-milk" colored pigmentary patches caused by increased melanin content within melanocytes and keratinocytes. For a diagnosis of NF1, at least **6 or more CALMs** (measuring >5 mm in prepubertal and >15 mm in postpubertal individuals) are required. **2. Why the Other Options are Incorrect:** * **Addison’s Disease:** Characterized by **diffuse hyperpigmentation** (bronzing) of the skin and mucous membranes due to increased ACTH levels, which stimulate melanocytes. It does not present with discrete CALMs. * **Peutz-Jeghers Syndrome:** Presents with **mucocutaneous lentigines** (small, dark brown-to-black macules), typically located on the lips, buccal mucosa, and digits, associated with gastrointestinal hamartomatous polyposis. * **Hyperpituitarism:** Excessive growth hormone (Acromegaly) or ACTH (Cushing’s disease) can cause skin thickening or generalized hyperpigmentation, but not localized CALMs. **3. NEET-PG High-Yield Pearls:** * **Crowe’s Sign:** Axillary or inguinal freckling; a pathognomonic sign for NF1. * **Lisch Nodules:** Iris hamartomas seen on slit-lamp exam in NF1. * **Coast of California vs. Maine:** NF1 spots have smooth borders (California), whereas **McCune-Albright Syndrome** features CALMs with irregular, "jagged" borders (Coast of Maine). * **Other CALM associations:** Tuberous Sclerosis, Fanconi Anemia, and Ataxia-telangiectasia.

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: 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.

Q: Which of the following conditions does NOT cause diffuse hyperpigmentation?

Hermansky-Pudlak Syndrome. **Explanation:** The correct answer is **Hermansky-Pudlak Syndrome (D)** because it is a form of **oculocutaneous albinism**, which results in **hypopigmentation** (diffuse lightness of skin, hair, and eyes), not hyperpigmentation. It is an autosomal recessive disorder characterized by a triad of tyrosinase-positive albinism, platelet storage pool deficiency (leading to bleeding diathesis), and lysosomal accumulation of ceroid lipofuscin (leading to pulmonary fibrosis and granulomatous colitis). **Why the other options are incorrect:** * **Addison Disease (C):** This is a classic cause of diffuse hyperpigmentation. Low cortisol levels lead to a compensatory increase in ACTH. Since ACTH and Melanocyte-Stimulating Hormone (MSH) share a common precursor (POMC), the excess ACTH stimulates melanocytes, causing generalized bronzing of the skin and mucous membranes. * **Nelson’s Syndrome (B):** This occurs after bilateral adrenalectomy for Cushing's disease. The loss of negative feedback leads to an ACTH-secreting pituitary adenoma, resulting in extremely high ACTH levels and profound diffuse hyperpigmentation. * **Busulfan Administration (A):** Busulfan is a cytotoxic alkylating agent known to cause "busulfan tan," a side effect characterized by diffuse, slate-gray hyperpigmentation in approximately 5-10% of patients. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-induced hyperpigmentation:** Common culprits include Antimalarials (blue-gray), Clofazimine (reddish-brown), Amiodarone (slate-gray), and Minocycline. * **Endocrine causes:** Aside from Addison’s, hyperthyroidism and acromegaly can also cause diffuse hyperpigmentation. * **Hermansky-Pudlak vs. Chédiak-Higashi:** Both involve albinism and bleeding; however, Chédiak-Higashi is distinguished by **giant lysosomal granules** in neutrophils and recurrent infections.

Question 1

Cafe-au-lait spots on the skin are characteristic of which of the following conditions?

Accepted Answer

Von Recklinghausen disease

Answer

Addison's disease

Answer

Peutz-Jeghers syndrome

Answer

Hyperpituitarism

Question 2

A 36-year-old female patient presents with complaints of dark spots on her face over the past few years. She first noticed these lesions after her first childbirth five years ago, and they worsened during her second pregnancy two years ago. She has no other medical problems and is only taking oral contraceptive pills. Her vital signs are within normal limits. Examination reveals multiple, discrete, confluent, well-demarcated patches of brown hyperpigmentation on her forehead, cheeks, and chin. Complete blood count and thyroid profile tests are normal. What is the most appropriate advice regarding her condition?

Accepted Answer

Melasma may or may not return with each subsequent pregnancy.

Answer

Oral contraceptive pills are not likely to influence this condition.

Answer

This condition is a sign of an underlying endocrine disease.

Answer

This condition persists for a lifetime.

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

Which of the following is not a ceruloderma?

Accepted Answer

Cockade nevus

Answer

Nevus of Ota

Answer

Nevus of Ito

Answer

Mongolian spot

Question 5

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 6

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 7

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 8

Characteristic skin lesion in Peutz-Jeghers syndrome is?

Accepted Answer

Lentigines

Answer

Freckles

Answer

Cafe au lait spots

Answer

Adenoma sebaceum

Question 9

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

Question 10

Which of the following conditions does NOT cause diffuse hyperpigmentation?

Accepted Answer

Hermansky-Pudlak Syndrome

Answer

Busulfan administration

Answer

Nelson's syndrome

Answer

Addison disease

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

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