Pigmentary Disorders Practice Questions

Q: Acanthosis nigricans can occur due to which of the following mechanisms?

Hyperkeratosis of epidermal cells. **Explanation:** **Acanthosis Nigricans (AN)** is a common dermatological condition characterized by hyperpigmented, velvety plaques, typically found in intertriginous areas like the neck and axilla. **Why Option C is correct:** The primary histopathological feature of Acanthosis Nigricans is **hyperkeratosis** (thickening of the stratum corneum) and **papillomatosis** (undulation of the dermal papillae). Despite its name, "acanthosis" (thickening of the stratum spinosum) is actually minimal or absent in this condition. The dark, "pigmented" appearance is not due to increased melanin, but rather a visual effect caused by the thickened, folded epidermis (hyperkeratosis). **Why other options are incorrect:** * **Option A:** While growth factors (like IGF-1) stimulate the epidermis, the hallmark is the accumulation of keratinocytes at the surface (hyperkeratosis) rather than a simple increase in basal cell multiplication. * **Option B:** Cornification is a normal physiological process of keratinocyte maturation. In AN, this process is exaggerated or altered leading to hyperkeratosis, but "cornification of basal cells" is not a recognized pathological mechanism. **High-Yield Clinical Pearls for NEET-PG:** * **Pathogenesis:** Driven by the stimulation of **Insulin-like Growth Factor (IGF-1) receptors** or **Fibroblast Growth Factor Receptors (FGFR)** on keratinocytes and fibroblasts. * **Associations:** * **Type 1 (Hereditary):** Benign. * **Type 2 (Endocrine):** Most common; associated with **Insulin Resistance**, PCOS, and Diabetes. * **Type 3 (Obesity):** Pseudo-acanthosis nigricans. * **Type 4 (Drug-induced):** Nicotinic acid, systemic corticosteroids, OCPs. * **Type 5 (Malignant):** Sudden onset, extensive involvement; most commonly associated with **Gastric Adenocarcinoma**. * **Triad of Malignant AN:** Acanthosis nigricans + Tripe palms + Leser-Trélat sign.

Q: Which of the following is NOT true about acanthosis nigricans?

It is more common in women with PCOD and normal weight.. **Explanation:** Acanthosis Nigricans (AN) is a common dermatosis characterized by hyperpigmented, velvety, verrucous plaques. **Why Option B is the correct answer (False statement):** While AN is a hallmark of Polycystic Ovarian Disease (PCOD), it is strongly associated with **obesity and insulin resistance**, not normal weight. In PCOD, hyperinsulinemia stimulates insulin-like growth factor (IGF-1) receptors on keratinocytes and fibroblasts, leading to epidermal proliferation. While "lean PCOS" exists, AN is significantly more prevalent in those with an elevated BMI. **Analysis of other options:** * **Option A:** AN is the most reliable cutaneous marker for **insulin resistance** and hyperinsulinemia. It is frequently seen in Type 2 Diabetes Mellitus and Metabolic Syndrome. * **Option C:** The classic distribution of AN is **intertriginous/flexural areas**, most commonly the axillae, back of the neck (nape), groin, and waistline. * **Option D:** **Malignant Acanthosis Nigricans** is a paraneoplastic syndrome, most commonly associated with **Gastric Adenocarcinoma**. It usually presents with rapid onset, extensive involvement, and "tripe palms." **High-Yield Clinical Pearls for NEET-PG:** * **Histopathology:** Shows hyperkeratosis and papillomatosis. Interestingly, "acanthosis" (thickening of the stratum spinosum) is actually minimal despite the name. * **Tripe Palms:** Rugose appearance of palms; if seen with AN, it highly suggests internal malignancy (Lung or Gastric). * **Pseudo-acanthosis nigricans:** The term used when AN is specifically caused by obesity. * **Drug-induced AN:** Can be caused by Nicotinic acid, systemic corticosteroids, and OCPs.

Q: Which of the following is not associated with cafe-au-lait spots?

Von Hippel-Lindau Syndrome. **Explanation:** Café-au-lait macules (CALMs) are flat, pigmented skin lesions caused by increased melanin content in the epidermis. While isolated spots are common in the general population, multiple CALMs are hallmark features of several neurocutaneous and genetic syndromes. **Why Von Hippel-Lindau (VHL) Syndrome is the correct answer:** VHL syndrome is a phakomatosis characterized by visceral cysts and benign/malignant tumors, most notably **hemangioblastomas** (cerebellum, retina, spinal cord), pheochromocytomas, and renal cell carcinomas. Unlike other neurocutaneous syndromes, VHL is **not** typically associated with café-au-lait spots. Its primary cutaneous manifestations, if present, are rare and usually involve port-wine stains. **Analysis of Incorrect Options:** * **Neurofibromatosis Type 1 (NF1):** CALMs are the earliest clinical sign. The diagnostic criteria require $\geq$ 6 spots ($>$5mm in prepubertal and $>$15mm in postpubertal individuals). * **Tuberous Sclerosis (TSC):** While the classic skin findings are ash-leaf spots and angiofibromas, CALMs occur in approximately 15-28% of TSC patients, making it a recognized association. * **Russell-Silver Syndrome:** This is a growth retardation syndrome characterized by triangular facies and limb asymmetry; CALMs are a frequently documented cutaneous finding in these patients. **High-Yield Clinical Pearls for NEET-PG:** * **McCune-Albright Syndrome:** Features large, unilateral CALMs with irregular "Coast of Maine" borders, associated with polyostotic fibrous dysplasia and precocious puberty. * **NF1 CALMs:** Typically have smooth "Coast of California" borders. * **Fanconi Anemia:** A high-yield hematological association where CALMs are seen alongside thumb/radius defects and pancytopenia. * **Legius Syndrome:** A "NF1-like" syndrome presenting with multiple CALMs but lacking Lisch nodules or neurofibromas.

Q: Which of the following is false regarding acanthosis nigricans?

It is a confirmatory sign of malignancy.. **Explanation:** Acanthosis Nigricans (AN) is a common dermatological marker characterized by velvety, hyperpigmented, and verrucous plaques, typically involving intertriginous areas like the axilla and neck. **Why Option C is the correct (False) statement:** Acanthosis nigricans is **not** a confirmatory sign of malignancy. While it can be associated with internal cancers (Malignant Acanthosis Nigricans), it is far more commonly associated with benign conditions such as obesity, insulin resistance, and polycystic ovary syndrome (PCOS). Therefore, its presence is a clinical clue that necessitates further investigation, but it is not diagnostic of cancer on its own. **Analysis of other options:** * **Option A:** It can be a **prognostic indicator**. In malignant AN, the severity and extent of the skin lesions often parallel the course of the underlying tumor. Improvement in the skin may indicate successful treatment, while a flare-up may signal recurrence. * **Option B:** This describes the classic **morphology**. The "velvety" texture is due to epidermal papillomatosis and hyperkeratosis. * **Option C:** **Gastric adenocarcinoma** is indeed the most common malignancy associated with the sudden, explosive onset of malignant AN. **High-Yield Clinical Pearls for NEET-PG:** * **Tripe Palms:** Rugose hyperkeratosis of the palms; often associated with malignant AN (usually lung or gastric cancer). * **Sign of Leser-Trélat:** Sudden eruption of multiple seborrheic keratoses; often co-exists with malignant AN. * **Histopathology:** Shows hyperkeratosis and papillomatosis. Interestingly, "acanthosis" (thickening of the stratum spinosum) is actually minimal despite the name. * **Drug-induced AN:** Can be caused by Nicotinic acid, systemic corticosteroids, and OCPs.

Q: All statements regarding Vitiligo are true except:

Leukotrichia indicates a good prognosis.. **Explanation:** Vitiligo is an acquired pigmentary disorder characterized by the destruction of melanocytes. Understanding the prognostic factors and treatment modalities is crucial for NEET-PG. **Why Option D is the Correct Answer (The False Statement):** **Leukotrichia** refers to the whitening of hair within a vitiligo patch. Melanocyte reservoirs are located in the **outer root sheath of hair follicles**. When these reservoirs are destroyed, the hair turns white, and there are no remaining melanocytes to repigment the skin. Therefore, leukotrichia is a **poor prognostic sign** and often indicates that the lesion will be resistant to medical therapy, potentially requiring surgical intervention. **Analysis of Other Options:** * **Option A:** Genetic predisposition is well-established. About 20-30% of patients have a positive family history, and it is associated with specific HLA types (e.g., HLA-DR4, DQB1) and other autoimmune conditions. * **Option B:** **Narrow-band UVB (311 nm)** is currently the gold standard for generalized vitiligo. It is highly effective, has fewer side effects than PUVA, and stimulates the migration of melanocytes from the hair follicle. * **Option C:** Topical corticosteroids (high potency) or Calcineurin inhibitors (Tacrolimus) are the first-line treatments for **localized vitiligo**, especially in new-onset cases. **High-Yield Clinical Pearls for NEET-PG:** * **Koebner Phenomenon:** Development of vitiligo at sites of trauma (Common in Type B/Generalized Vitiligo). * **Segmental Vitiligo:** Usually has an early onset, follows a dermatomal pattern, and does not typically show the Koebner phenomenon. * **Most Common Site:** Periorificial areas (mouth, eyes) and tips of fingers/toes (Acrofacial). * **Sites with Poor Prognosis:** Mucosa, fingertips (glabrous skin lacking hair follicles), and areas with leukotrichia.

Q: A lady develops pigmentation on the bridge of her nose and cheeks upon exposure to sunlight. What is the most likely diagnosis?

Chloasma. ### Explanation **Correct Answer: A. Chloasma (Melasma)** **Concept:** Chloasma, commonly known as melasma, is an acquired hypermelanosis characterized by symmetrical, brownish macules and patches on sun-exposed areas, most typically the **bridge of the nose and cheeks** (malar distribution). It is significantly exacerbated by **UV radiation**, which stimulates melanocytes to produce excess melanin. While it can occur in anyone, it is most frequently seen in women due to hormonal influences (pregnancy, oral contraceptives). **Analysis of Incorrect Options:** * **B. Systemic Lupus Erythematosus (SLE):** While SLE presents with a "butterfly rash" on the nose and cheeks, it is typically an **erythematous (red)**, inflammatory, and often scaly rash, rather than pure pigmentation. It is also associated with systemic features like joint pain or renal involvement. * **C. Photodermatitis:** This is an umbrella term for skin reactions to light. It usually presents as an **acute inflammatory response** (redness, itching, vesicles, or scaling) rather than localized, stable brown pigmentation on the malar area. * **D. Rosacea:** This is a chronic inflammatory condition characterized by **facial flushing, telangiectasia, papules, and pustules**. While triggered by sunlight, it presents with redness and vascular changes rather than hyperpigmentation. **High-Yield Clinical 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** type enhances under Wood's lamp, while **Dermal** type does not. * **Treatment Gold Standard:** **Kligman’s Formula** (Triple Combination Therapy): Hydroquinone + Tretinoin + Topical Steroid (e.g., Fluocinolone). * **Differential Diagnosis:** Always differentiate from **Ochronosis** (side effect of long-term hydroquinone) which shows "sooty" pigmentation.

Q: Which of the following is NOT a feature of cafe-au-lait spots?

Most common pigmented lesion. **Explanation:** The correct answer is **D (Most common pigmented lesion)**. While café-au-lait macules (CALMs) are common, the most common pigmented lesions in humans are **melanocytic nevi (moles)** or **ephelides (freckles)**, depending on the population and sun exposure. **Why Option D is incorrect (and thus the right answer):** CALMs are present in about 10-20% of the normal population. They are significant clinical markers, but they do not hold the title of the "most common" pigmented lesion. **Analysis of other options:** * **A. Larger size:** Unlike freckles (which are 1-3 mm), CALMs are typically larger, ranging from 0.5 cm to over 20 cm. * **B. Arise independent of sun exposure:** This is a key diagnostic feature. Unlike freckles, which darken and increase in number with UV light, CALMs are present at birth or early childhood and do not change with sun exposure. * **C. Contain aggregates of melanosomes:** Histologically, CALMs show increased melanin content in basal keratinocytes and **giant melanosomes (macromelanosomes)**, particularly when associated with Neurofibromatosis Type 1 (NF-1). **High-Yield Clinical Pearls for NEET-PG:** * **NF-1 Criteria:** 6 or more CALMs (>5mm in prepubertal; >15mm in postpubertal individuals) is a major diagnostic criterion. * **Coast of California:** Smooth borders (seen in NF-1). * **Coast of Maine:** Irregular, "jagged" borders (seen in **McCune-Albright Syndrome**). * **Differential Diagnosis:** CALMs are also seen in Legius syndrome, Noonan syndrome, and Fanconi anemia.

Q: Which of the following drugs does NOT cause pigmented lesions of the oral mucosa?

Nifedipine. **Explanation:** The correct answer is **Nifedipine**. **1. Why Nifedipine is correct:** Nifedipine is a Calcium Channel Blocker (CCB) primarily associated with **Gingival Hyperplasia** (overgrowth), not hyperpigmentation. While it affects the oral cavity, it does not stimulate melanocytes or lead to the deposition of pigments in the oral mucosa. **2. Analysis of incorrect options:** * **Zidovudine (AZT):** This antiretroviral drug is a classic cause of hyperpigmentation. It can cause diffuse or longitudinal melanonychia (nails) and bluish-black pigmentation of the oral mucosa and skin. * **Minocycline:** A tetracycline derivative known for causing "slate-gray" pigmentation. It can affect the skin, nails, bones, sclera, and specifically the oral mucosa (often involving the hard palate or gingiva). * **Oral Contraceptives (OCPs):** Estrogen and progesterone can stimulate melanogenesis. While more commonly associated with Melasma (facial pigmentation), OCPs are a documented cause of drug-induced oral mucosal hyperpigmentation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug-induced Gingival Hyperplasia:** Remember the mnemonic **"P-C-P"** (Phenytoin, Cyclosporine, and Panipidine/Nifedipine). * **Other drugs causing Oral Pigmentation:** Antimalarials (Chloroquine/Hydroxychloroquine – often on the hard palate), Cytotoxic drugs (Cyclophosphamide, Doxorubicin), and Heavy metals (Lead/Bismuth – "Lead lines" at the gingival margin). * **Laugier-Hunziker Syndrome:** A key differential for oral pigmentation; it presents with mucosal lentigines and longitudinal melanonychia but is *idiopathic* (not drug-induced).

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

Peutz-Jeghers syndrome. The clinical presentation of **mucocutaneous pigmentation** (pigmented macules on palms, soles, and oral mucosa) combined with **anemia** and **abdominal pain** is classic for **Peutz-Jeghers Syndrome (PJS)**. **Why C is correct:** PJS is an autosomal dominant condition caused by a mutation in the **STK11 (LKB1)** gene. It is characterized by: 1. **Hamartomatous polyps:** Primarily in the small intestine, which can cause intussusception (leading to abdominal pain) and chronic occult bleeding (leading to iron-deficiency anemia). [1] 2. **Melanocytic macules:** Distinctive dark spots on the lips, buccal mucosa, palms, and soles. Unlike freckles, these do not fade with sun exposure. **Why the other options are incorrect:** * **A. Albright’s Syndrome (McCune-Albright):** Presents with "Café-au-lait" spots (large, irregular borders), polyostotic fibrous dysplasia, and precocious puberty. It does not involve oral mucosal pigmentation or intestinal polyps. * **B. Cushing’s Syndrome:** Characterized by weight gain, moon facies, striae, and hypertension. While hyperpigmentation can occur in ACTH-dependent causes, it is generalized and lacks the specific macules and GI symptoms seen here. * **C. Incontinentia Pigmenti:** An X-linked dominant skin disorder that evolves through stages (vesicular, verrucous, hyperpigmented). The pigmentation follows Blaschko’s lines and is associated with dental and CNS anomalies, not GI polyposis. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant (STK11 gene on Chromosome 19p). * **Cancer Risk:** Patients have a significantly increased risk of GI cancers and extra-intestinal malignancies (Breast, Pancreas, Ovary/Sertoli cell tumors). [1] * **Most common site of polyps:** Small intestine (Jejunum). * **Management:** Regular screening with upper/lower GI endoscopy and imaging for extra-intestinal tumors.

Question 1

Acanthosis nigricans can occur due to which of the following mechanisms?

Accepted Answer

Hyperkeratosis of epidermal cells

Answer

Increased multiplication of basal cells

Answer

Cornification of basal cells

Answer

All of the above

Question 2

Which of the following is NOT true about acanthosis nigricans?

Accepted Answer

It is more common in women with PCOD and normal weight.

Answer

It is a cutaneous marker of insulin resistance.

Answer

It affects flexural areas such as axillae, waist, and groin.

Answer

It can be seen in gastrointestinal malignancy.

Question 3

Acanthosis nigricans is a known paraneoplastic sign associated with which of the following conditions?

Accepted Answer

Carcinoma of the breast

Answer

Colonic carcinoma

Answer

Freckle

Answer

Squamous cell carcinoma of the skin

Question 4

Which of the following is not associated with cafe-au-lait spots?

Accepted Answer

Von Hippel-Lindau Syndrome

Answer

Neurofibromatosis

Answer

Tuberous sclerosis

Answer

Russell-Silver syndrome

Question 5

Which of the following is false regarding acanthosis nigricans?

Accepted Answer

It is a confirmatory sign of malignancy.

Answer

It can be a prognostic indicator.

Answer

It presents as velvety plaques with hyperpigmentation.

Answer

Gastric adenocarcinoma is the most common malignant association.

Question 6

All statements regarding Vitiligo are true except:

Accepted Answer

Leukotrichia indicates a good prognosis.

Answer

Genetic predisposition is present.

Answer

Narrow-band UV-B therapy is very effective.

Answer

Topical steroids are used for localized lesions.

Question 7

A lady develops pigmentation on the bridge of her nose and cheeks upon exposure to sunlight. What is the most likely diagnosis?

Accepted Answer

Chloasma

Answer

Systemic lupus erythematosus

Answer

Photodermatitis

Answer

Rosacea

Question 8

Which of the following is NOT a feature of cafe-au-lait spots?

Accepted Answer

Most common pigmented lesion

Answer

Larger size

Answer

Arise independent of sun exposure

Answer

Contain aggregates of melanosomes

Question 9

Which of the following drugs does NOT cause pigmented lesions of the oral mucosa?

Accepted Answer

Nifedipine

Answer

Zidovudine

Answer

Minocycline

Answer

Oral contraceptives

Question 10

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

Accepted Answer

Peutz-Jeghers syndrome

Answer

Albright's syndrome

Answer

Cushing's syndrome

Answer

Incontinentia pigmenti

Pigmentary Disorders — MCQs

Pigmentary Disorders — MCQs

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