Melasma — MCQs
Elderly man with a long-standing mole on his face that is increasing in size and showing an irregular border. Diagnosis:
All are predisposing factors of Deep Vein thrombosis, EXCEPT :
PUVA therapy is used in all except:
Which of the following is not true about hydroquinone?
Which of the following is an example of a barrier method of contraception?
A 15cm hyperpigmented macule on an adolescent male undergoes changes such as coarseness, growth of hair & acne. Diagnosis is?
A 35-year-old obese woman presents with recurrent lesions in both axilla in summer season. Wood lamp examination is shown. The diagnosis is:
What is the most common association with Acanthosis nigricans?
An increased incidence of vitiligo is found in association with which of the following conditions?
A 'silver tattoo' is due to deposition of which substance in the oral mucosa?
Melasma Indian Medical PG Practice Questions and MCQs
Question 1: Elderly man with a long-standing mole on his face that is increasing in size and showing an irregular border. Diagnosis:
- A. Superficial spreading melanoma
- B. Nodular melanoma
- C. Acral melanoma
- D. Lentigo maligna (Correct Answer)
Explanation: ***Lentigo maligna*** - This type of melanoma commonly affects **elderly individuals** and presents as a **slowly enlarging, irregularly bordered, flat or slightly raised pigmented lesion** on sun-exposed areas like the face. - It often has a **long radial growth phase** before progressing to invasive lentigo maligna melanoma. *Superficial spreading melanoma* - While common, it typically presents on the **trunk or extremities** and has a faster growth rate compared to lentigo maligna. - It often appears as a **flat, asymmetrical lesion with varied colors and irregular borders**, but the age and location details point away from this. *Nodular melanoma* - This is an **aggressive form** that grows vertically from the start, presenting as a **dark, raised, often ulcerated nodule** and typically has a shorter history of rapid growth. - It lacks the characteristic long-standing, flat growth pattern described in the elderly patient's face. *Acral melanoma* - This rare type occurs on the **palms, soles, or under the nails (subungual)**, not typically on the face. - It often appears as a **pigmented streak or patch** in these acral locations.
Question 2: All are predisposing factors of Deep Vein thrombosis, EXCEPT :
- A. Lower limb trauma
- B. Cushing's syndrome
- C. Hip surgery
- D. Subungual melanoma (Correct Answer)
Explanation: ***Subungual melanoma*** - This is a rare form of melanoma that develops under the nail, and while serious, it is **not a recognized predisposing factor for deep vein thrombosis (DVT)**. Its primary concerns are local invasion and metastasis. - Unlike conditions affecting blood clotting or endothelium, **subungual melanoma does not directly promote hypercoagulability, venous stasis, or endothelial damage** that contribute to DVT. *Lower limb trauma* - **Trauma to the lower limb** can cause **endothelial damage** to blood vessels and **venous stasis** due to immobility or swelling, both key components of **Virchow's triad** for DVT [1]. - **Fractures or severe soft tissue injuries** often necessitate immobilization and can lead to inflammation, further increasing the risk of clot formation [1]. *Cushing's syndrome* - **Cushing's syndrome** is associated with **hypercoagulability** due to increased levels of clotting factors, such as **factor VIII** and **fibrinogen**, and decreased fibrinolytic activity. - The **elevated cortisol levels** seen in Cushing's syndrome [2] can directly contribute to a prothrombotic state, significantly increasing DVT risk. *Hip surgery* - **Major orthopedic surgeries**, especially hip surgery [1], are well-known to cause significant **venous stasis** and **endothelial damage**. - **Post-operative immobility** and a generalized **inflammatory response** following surgery contribute to a high risk of DVT formation [1].
Question 3: PUVA therapy is used in all except:
- A. Psoriasis
- B. Vitiligo
- C. Mycosis fungoides
- D. Melasma (Correct Answer)
Explanation: ***Melasma*** - **PUVA (Psoralen plus UVA) therapy** is contraindicated in melasma due to its potential to worsen hyperpigmentation and cause paradoxical darkening. - Melasma is best managed with topical agents like **hydroquinone**, **tretinoin**, and chemical peels, along with strict **sun protection**. *Psoriasis* - **PUVA therapy** is a well-established and effective treatment for moderate to severe psoriasis, especially for patients with widespread plaques. - It works by inhibiting DNA synthesis and cell proliferation in rapidly dividing keratinocytes, leading to a reduction in psoriatic lesions. *Vitiligo* - **PUVA therapy** is a common treatment for vitiligo, stimulating melanocyte activity and promoting repigmentation in affected areas. - Psoralen sensitizes melanocytes to UVA light, which then encourages melanin production. *Mycosis fungoides* - In its early stages, **mycosis fungoides**, a cutaneous T-cell lymphoma, can be effectively treated with **PUVA therapy**. - PUVA induces apoptosis of malignant T-cells in the skin, leading to remission of skin lesions.
Question 4: Which of the following is not true about hydroquinone?
- A. Response is incomplete and pigmentation may recur
- B. It inhibits tyrosinase
- C. It requires prescription strength concentrations above 2%
- D. It should not be used for melasma or chloasma of pregnancy (Correct Answer)
Explanation: ***It should not be used for melasma or chloasma of pregnancy*** - This statement is **NOT TRUE** - hydroquinone is actually a **first-line treatment for melasma** including chloasma (melasma of pregnancy) - Hydroquinone 2-4% is one of the **most effective topical agents** for treating melasma and is widely recommended in dermatological guidelines - While hydroquinone use during **active pregnancy** is approached with caution (FDA Category C), it is definitely indicated for treating melasma/chloasma **after pregnancy** and for general melasma in non-pregnant patients - The condition (melasma/chloasma) is appropriately treated with hydroquinone; only the **timing during pregnancy** requires consideration *Response is incomplete and pigmentation may recur* - This is a **TRUE statement** about hydroquinone therapy - Treatment response is often **incomplete** with partial lightening of hyperpigmentation - **Recurrence is common** after discontinuation, especially with continued sun exposure or hormonal triggers - Maintenance therapy is often needed to sustain results *It inhibits tyrosinase* - This is a **TRUE statement** - hydroquinone's primary mechanism of action - Acts as a **competitive inhibitor of tyrosinase**, the rate-limiting enzyme in melanin synthesis - This inhibition reduces melanin production in melanocytes, leading to depigmentation *It requires prescription strength concentrations above 2%* - This is a **TRUE statement** in most countries including India and the USA - Hydroquinone concentrations **≤2%** are available over-the-counter (OTC) - Concentrations **>2% (typically 3-4%)** require a prescription - Higher concentrations provide greater efficacy but also increased risk of side effects like ochronosis
Question 5: Which of the following is an example of a barrier method of contraception?
- A. Hormonal contraceptive
- B. IUD
- C. Condom (Correct Answer)
- D. Sterilization
Explanation: ***Condom*** - A **condom** acts as a physical barrier, preventing sperm from reaching the egg. - Both male and female condoms are examples of **barrier contraception**. *Hormonal contraceptive* - **Hormonal contraceptives** work by preventing ovulation, thickening cervical mucus, or altering the uterine lining, not by physically blocking sperm. - Examples include oral contraceptive pills, patches, and vaginal rings. *IUD* - An **intrauterine device (IUD)**, whether hormonal or copper, primarily prevents conception by creating an inhospitable environment for sperm or by preventing implantation. - It is a long-acting reversible contraceptive, not a barrier method. *Sterilization* - **Sterilization** (e.g., tubal ligation or vasectomy) is a permanent method of contraception that prevents the transport of eggs or sperm, respectively. - It does not involve a physical barrier to block sperm during intercourse.
Question 6: A 15cm hyperpigmented macule on an adolescent male undergoes changes such as coarseness, growth of hair & acne. Diagnosis is?
- A. Melanocytic nevus
- B. Becker nevus (Correct Answer)
- C. Sebaceous nevus
- D. Sebaceous adenoma
Explanation: ***Becker nevus*** - A Becker nevus is a **hyperpigmented patch** that typically appears during adolescence in males, often on the shoulder or upper trunk. - It characteristically becomes **hairy (hypertrichosis)**, more coarse, and can develop acne within the lesion, particularly during puberty due to androgen sensitivity. *Melanocytic nevus* - While melanocytic nevi are hyperpigmented, they generally do not show the characteristic changes of **coarseness, significant hair growth, or acne** within the lesion during adolescence. - They are typically stable in size and texture after initial development, with changes raising concern for **melanoma**. *Sebaceous nevus* - A sebaceous nevus is a **congenital lesion** often appearing as a yellowish-orange, waxy, or bumpy patch, usually on the scalp or face. - It does not typically present as a large, flat hyperpigmented macule that develops hair and acne in adolescence; instead, it may become verrucous or develop tumors in adulthood. *Sebaceous adenoma* - A sebaceous adenoma is a **benign tumor** of the sebaceous glands, usually appearing as a small, solitary, flesh-colored to yellowish papule or nodule, especially on the face. - It is not typically seen as a large, hyperpigmented macule that grows hair and acne over a broad area, as described in the question.
Question 7: A 35-year-old obese woman presents with recurrent lesions in both axilla in summer season. Wood lamp examination is shown. The diagnosis is:
- A. Ecthyma
- B. Erythrasma (Correct Answer)
- C. Impetigo contagiosa
- D. Bullous impetigo
Explanation: ***Erythrasma*** - Erythrasma is a superficial bacterial infection caused by **Corynebacterium minutissimum**, which commonly presents as red-brown patches in intertriginous areas like the axilla, especially in obese individuals and warm, humid conditions (summer season). - The distinctive **coral-red fluorescence under Wood's lamp** is due to porphyrin production by the bacteria, which is a classic diagnostic feature of erythrasma, as shown in the image. *Ecthyma* - Ecthyma is a deeper form of impetigo characterized by **ulcerative lesions with a thick, adherent crust** that extend into the dermis. - It is typically caused by *Streptococcus pyogenes* and sometimes *Staphylococcus aureus*, and would not exhibit coral-red fluorescence under Wood's lamp. *Impetigo contagiosa* - Impetigo contagiosa (non-bullous impetigo) presents with **honey-colored crusted lesions**, usually on the face and extremities. - While also a bacterial skin infection, it is typically caused by *Staphylococcus aureus* or *Streptococcus pyogenes* and does not show coral-red fluorescence under Wood's lamp. *Bullous impetigo* - Bullous impetigo is characterized by **flaccid bullae** (blisters) that rupture to form thin, varnish-like crusts, primarily caused by *Staphylococcus aureus* producing exfoliative toxins. - Similar to other forms of impetigo, it does not produce the coral-red fluorescence under Wood's lamp.
Question 8: What is the most common association with Acanthosis nigricans?
- A. Hypertension
- B. Diabetes Mellitus
- C. Obesity (Correct Answer)
- D. Hypothyroidism
Explanation: **Explanation:** **Acanthosis Nigricans (AN)** is a common dermatological condition characterized by hyperpigmented, velvety plaques, typically found in intertriginous areas like the axilla and neck. **Why Obesity is the Correct Answer:** Obesity is the **most common** association and cause of Acanthosis Nigricans (Pseudo-acanthosis nigricans). The underlying mechanism is **Insulin Resistance**. In obese individuals, high levels of circulating insulin bind to **Insulin-like Growth Factor-1 (IGF-1) receptors** on keratinocytes and fibroblasts. This stimulates excessive proliferation of these cells, leading to the characteristic epidermal thickening and hyperpigmentation. **Analysis of Incorrect Options:** * **Diabetes Mellitus (B):** While AN is a strong cutaneous marker for Type 2 Diabetes, it usually precedes the clinical onset of diabetes. Obesity remains the primary driver and more frequent association. * **Hypertension (A) & Hypothyroidism (D):** These are often part of the "Metabolic Syndrome" or associated endocrinopathies (like PCOS), but they are not the primary or most common cause of the skin changes seen in AN. **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 internal malignancy, most commonly **Gastric Adenocarcinoma**. * **Histopathology:** Shows hyperkeratosis and papillomatosis. Note that "acanthosis" (thickening of the stratum spinosum) is actually minimal despite the name. * **Common Sites:** Neck (most common), axilla, groins, and knuckles. * **Drug-induced AN:** Can be caused by Nicotinic acid, systemic corticosteroids, and OCPs.
Question 9: An increased incidence of vitiligo is found in association with which of the following conditions?
- A. Psoriasis
- B. Nutritional deficiency
- C. Old age
- D. Diabetes mellitus (Correct Answer)
Explanation: **Explanation:** **Vitiligo** is a chronic autoimmune skin disorder characterized by the destruction of melanocytes. The key medical concept to understand for NEET-PG is that vitiligo is frequently associated with other **organ-specific autoimmune disorders**. **1. Why Diabetes Mellitus is correct:** Vitiligo is part of a spectrum of autoimmune polyendocrine syndromes. There is a statistically significant association between vitiligo and **Type 1 Diabetes Mellitus** (and occasionally Type 2) due to shared genetic susceptibility and autoimmune pathways. Other common associations include: * **Thyroid disorders** (most common association, especially Hashimoto’s thyroiditis). * Pernicious anemia. * Addison’s disease. * Alopecia areata. **2. Why the other options are incorrect:** * **Psoriasis (A):** While both are T-cell mediated inflammatory skin diseases, psoriasis is not classically associated with the systemic autoimmune cluster seen in vitiligo. * **Nutritional deficiency (B):** Vitiligo is an autoimmune process, not a nutritional one. While some studies suggest low Vitamin B12 or Vitamin D levels in vitiligo patients, deficiency is not a causative or strongly associated factor. * **Old age (C):** Vitiligo typically has an early onset; 50% of cases begin before age 20. It is not a degenerative condition of aging. **High-Yield Clinical Pearls for NEET-PG:** * **Most common association:** Thyroid dysfunction (check TSH in vitiligo patients). * **Koebner Phenomenon:** Vitiligo shows positivity (depigmentation at sites of trauma). * **Vogt-Koyanagi-Harada Syndrome:** Vitiligo associated with uveitis, meningitis, and auditory symptoms. * **Treatment of choice:** Narrowband UVB (NB-UVB) is the gold standard for generalized vitiligo.
Question 10: A 'silver tattoo' is due to deposition of which substance in the oral mucosa?
- A. Silver amalgam in mucosa (Correct Answer)
- B. Silver amalgam in bone
- C. Silver amalgam in dentin
- D. Silver amalgam in enamel
Explanation: **Explanation:** The correct answer is **A. Silver amalgam in mucosa.** An **amalgam tattoo** (often referred to as a "silver tattoo") is a common iatrogenic lesion caused by the accidental implantation of dental restorative material into the oral soft tissues. This typically occurs during the placement or removal of silver amalgam fillings, or during endodontic procedures (like an apicoectomy). **Why Option A is correct:** The "tattoo" effect occurs when silver particles from the amalgam are embedded into the **lamina propria** of the oral mucosa. Once in the tissue, the silver salts stain the reticulin fibers of the basement membrane and blood vessel walls, resulting in a localized, asymptomatic, slate-grey to bluish-black macule. **Why other options are incorrect:** * **Options B, C, and D:** While amalgam is used to restore dentin and enamel, and may occasionally come into contact with bone during surgery, the clinical term "silver tattoo" specifically refers to the visible **mucosal pigmentation**. Pigmentation within the hard tissues (bone, dentin, enamel) does not manifest as a "tattoo" because these tissues are not superficial or translucent enough to show the characteristic localized blue-grey discoloration seen on the surface of the gums or cheeks. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Site:** The gingiva and alveolar mucosa are the most frequent sites. * **Radiology:** On a periapical X-ray, radiopaque (white) speckles may be visible at the site of the tattoo if the fragments are large enough. * **Differential Diagnosis:** It is crucial to differentiate an amalgam tattoo from a **malignant melanoma**. If the lesion is expanding or lacks a history of dental work, a biopsy is mandatory. * **Histology:** Characterized by black, granular deposits along collagen fibers and around small blood vessels.
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