Melanocytic Nevi — MCQs
Identify the skin lesion shown in the image.
Which of the following nevus types is most commonly associated with malignant melanoma development?
A farmer presented with a black mole on the cheek. It increased in size, more than 6mm with irregular borders and a central black lesion, what could be the diagnosis?
A giant congenital melanocytic nevus is usually of what size?
What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
Patient with pigmented skin lesion shows pagetoid spread of atypical melanocytes. Diagnosis?
What is the dermatological sign associated with carcinoma of the stomach?
What is the most common malignancy found in Marjolin's ulcer?
What is a rodent ulcer?
What is the most common site for a rodent ulcer?
Melanocytic Nevi Indian Medical PG Practice Questions and MCQs
Question 1: Identify the skin lesion shown in the image.
- A. Becker nevus (Correct Answer)
- B. Hypopigmented macule
- C. Spitz nevus
- D. Epidermal nevus
Explanation: ***Becker nevus*** - This image clearly shows a large, **hyperpigmented patch with overlying coarse terminal hairs**, characteristic of a Becker nevus. - Becker nevi typically develop in adolescence and are often found on the shoulder or upper trunk, as seen here. *Hypopigmented macule* - A **hypopigmented macule** would appear as an area of skin with **reduced pigmentation** (lighter than the surrounding skin), which is contrary to the darker lesion shown. - There would also be no indication of **increased hair growth** within a typical hypopigmented macule. *Spitz nevus* - A Spitz nevus is a benign melanocytic nevus often appearing as a **dome-shaped, pink or red papule or nodule**, commonly on the face or limbs. - It does not present as a large, hairy, **hyperpigmented patch** as depicted in the image. *Epidermal nevus* - An epidermal nevus is a **congenital lesion** formed by an overgrowth of epidermal cells, but its appearance is typically a **verrucous (wart-like) plaque** or linearly arranged papules. - While it can be hyperpigmented, it generally **lacks the prominent hypertrichosis** (excessive hair growth) seen in the image.
Question 2: Which of the following nevus types is most commonly associated with malignant melanoma development?
- A. Junctional nevus
- B. Intradermal nevus
- C. Blue nevus
- D. Dysplastic nevus (Correct Answer)
Explanation: ***Dysplastic nevus*** (Correct) - **Dysplastic nevi** are considered precursor lesions and markers for increased risk of developing **malignant melanoma**. - Individuals with multiple dysplastic nevi have a significantly higher lifetime risk of melanoma compared to the general population. - Also known as **atypical nevi**, they show architectural disorder and cytologic atypia on histology. *Junctional nevus* (Incorrect) - **Junctional nevi** are benign moles with melanocytes located at the **dermo-epidermal junction**. - While theoretically a melanoma can arise from any nevus, junctional nevi are less frequently associated with melanoma development than dysplastic nevi. *Intradermal nevus* (Incorrect) - **Intradermal nevi** are benign moles where the melanocytes are located entirely within the **dermis**. - These nevi are generally stable, often appearing flesh-colored or light brown, and have a very low potential for malignant transformation. *Blue nevus* (Incorrect) - **Blue nevi** are benign lesions characterized by **deeply situated dermal melanocytes** that produce a blue or blue-black color due to the Tyndall effect. - They are typically stable and have a very low risk of malignant transformation; however, rarely, an atypical blue nevus or cellular blue nevus can undergo malignant change.
Question 3: A farmer presented with a black mole on the cheek. It increased in size, more than 6mm with irregular borders and a central black lesion, what could be the diagnosis?
- A. Superficial spreading melanoma (Correct Answer)
- B. Acral lentigo melanoma
- C. Lentigo maligna melanoma
- D. Nodular melanoma
Explanation: ***Superficial spreading melanoma*** - This is the most common type of melanoma and often presents as a **mole with irregular borders**, varying colors, and a diameter greater than 6mm, consistent with the description. - The lesion typically grows **radially** across the skin surface before beginning vertical growth, indicated by the increase in size. *Acral lentigo melanoma* - This type of melanoma primarily affects the **palms, soles, and nail beds**, which is inconsistent with a lesion on the cheek. - It often appears as a **dark brown or black patch** that slowly enlarges, but its location is characteristic. *Lentigo maligna melanoma* - This melanoma typically occurs in **chronically sun-damaged skin** of the elderly, often on the head and neck, but usually presents as a **flat, irregularly shaped, tan or brown patch** with varying shades, which may not fit the description of a central black lesion within a larger mole. - It has a dominant **radial growth phase** and progresses slowly over many years before developing a nodular component. *Nodular melanoma* - This type is characterized by its **rapid vertical growth** and appearance as a **raised, dark, often dome-shaped lesion** from the outset. - While it can be black, the description of an "increased in size" mole with irregular borders and a central black lesion points more towards a spreading type rather than a rapidly growing nodule from the beginning.
Question 4: A giant congenital melanocytic nevus is usually of what size?
- A. 5-10cm
- B. 10-15 cm
- C. 15-20 cm
- D. 20 cm or greater (Correct Answer)
Explanation: ***20 cm or greater*** - A **giant congenital melanocytic nevus (GCMN)** is defined by its substantial size, typically measuring **20 cm or more in diameter** in an adult. - This large size is a key feature distinguishing it from smaller congenital nevi and is associated with a **higher risk of malignant transformation** and neurological complications such as **neurocutaneous melanosis**. *5-10cm* - A nevus of this size would be classified as a **small to medium congenital melanocytic nevus**, not a giant one. - While these nevi carry some risk of malignancy, it is significantly **lower than that of GCMN**. *10-15 cm* - This range falls under the category of a **medium congenital melanocytic nevus**. - While larger than small nevi, it does not meet the established criteria for a **giant congenital melanocytic nevus**. *15-20 cm* - A nevus of 15-20 cm is considered a **large congenital melanocytic nevus**, but it is still usually classified just below the threshold for a true **giant congenital melanocytic nevus** which is typically 20 cm or more. - Although it approaches the giant classification, the **20 cm demarcation** is critical for defining GCMN.
Question 5: What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
- A. Melanocytic nevus
- B. Becker nevus (Correct Answer)
- C. Sebaceous nevus
- D. Comedo nevus
Explanation: ***Correct: Becker nevus*** This diagnosis is supported by the description of a **hyperpigmented lesion** that is **enlarging** and has **hair growing from it**, typically appearing during adolescence or young adulthood. **Becker nevus** often presents as an **irregular, hyperpigmented patch**, usually on the shoulder or upper trunk, and is characteristically associated with **hypertrichosis** (increased terminal hair growth). The combination of location (shoulder), enlargement, and hair growth in a 15 mm lesion is classic for Becker nevus. *Incorrect: Melanocytic nevus* While **melanocytic nevi** are hyperpigmented, they typically do not continue to **enlarge significantly** after childhood and generally do not develop new onset **hypertrichosis** as a primary feature. The size (15 mm) and progressive growth combined with hair development are more characteristic of a Becker nevus than a common melanocytic nevus. *Incorrect: Sebaceous nevus* **Sebaceous nevi** are typically **yellow-orange to tan, waxy plaques**, often on the scalp or face, with a cobblestone or papillomatous texture. They are not primarily characterized by **hyperpigmentation** and terminal hair growth, but rather by sebaceous gland proliferation. *Incorrect: Comedo nevus* A **comedo nevus** presents as a linear or unilateral group of **dilated follicular openings** filled with keratinous material, resembling blackheads. It is not characterized by diffuse **hyperpigmentation** or the increased terminal hair growth described in this case.
Question 6: Patient with pigmented skin lesion shows pagetoid spread of atypical melanocytes. Diagnosis?
- A. Lentigo maligna
- B. Superficial spreading melanoma (Correct Answer)
- C. Blue nevus
- D. Nodular melanoma
Explanation: ### Superficial spreading melanoma - This is the most common type of melanoma and is characterized by a **radial growth phase** where atypical melanocytes spread along the **dermo-epidermal junction** and into the epidermis (pagetoid spread) [1]. - **Pagetoid spread**, referring to the upward migration of atypical melanocytes into the spinous and granular layers of the epidermis, is a hallmark histological feature. *Lentigo maligna* - This is a melanoma subtype primarily affecting **chronically sun-damaged skin** in older individuals, typically on the face. - While it has a prolonged **radial growth phase**, the atypical melanocytes tend to be confined to the **basal layer** and do not typically exhibit prominent pagetoid spread like superficial spreading melanoma. *Blue nevus* - A blue nevus is a **benign melanocytic lesion** characterized by the presence of dermal melanocytes that produce melanin deep within the dermis, giving it a characteristic blue or blue-gray color [2]. - It does not involve **atypical melanocytes** or **pagetoid spread** (upward migration of cells into the epidermis). *Nodular melanoma* - This is an aggressive subtype of melanoma characterized by a rapid **vertical growth phase** and minimal or absent radial growth phase [1]. - It presents as a **dark, raised nodule** and typically lacks the prominent pagetoid spread seen in the superficial spreading type, as its growth is primarily downward into the dermis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1151-1152. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1146.
Question 7: What is the dermatological sign associated with carcinoma of the stomach?
- A. Palmoplantar keratoderma
- B. Acquired ichthyosis
- C. Acanthosis Nigrans (Correct Answer)
- D. Acrokeratosis paraneopiastica
Explanation: **Explanation:** **Acanthosis Nigricans (AN)** is the correct answer. While AN is most commonly associated with insulin resistance and obesity (Benign AN), its sudden, severe, and widespread onset in an older individual—often involving the palms (tripe palms) and mucous membranes—is a classic **paraneoplastic syndrome**. **Malignant Acanthosis Nigricans** is most frequently associated with **adenocarcinomas of the gastrointestinal tract**, with **stomach cancer** being the most common (approx. 50-60% of cases). It is thought to be mediated by tumor-secreted growth factors like Transforming Growth Factor-alpha (TGF-α) acting on epidermal EGF receptors. **Analysis of Incorrect Options:** * **A. Palmoplantar Keratoderma (PPK):** While acquired PPK can be paraneoplastic (Howel-Evans Syndrome), it is specifically linked to **Esophageal carcinoma**, not primarily the stomach. * **B. Acquired Ichthyosis:** This sudden onset of "fish-like" scaling in adulthood is most strongly associated with **lymphomas** (specifically Hodgkin’s Lymphoma), rather than gastric malignancies. * **D. Acrokeratosis Paraneoplastica (Bazex Syndrome):** This presents with psoriasiform plaques on acral sites (ears, nose, fingers). It is highly specific for squamous cell carcinomas of the **upper aerodigestive tract** (head, neck, and esophagus). **High-Yield Clinical Pearls for NEET-PG:** * **Tripe Palms:** When AN affects the palms, appearing velvety and rugose, it is 90% predictive of internal malignancy. If seen with AN, think **Stomach CA**; if seen alone, think **Lung CA**. * **Leser-Trélat Sign:** The sudden eruption of multiple Seborrheic Keratoses is another major cutaneous marker for **Gastric Adenocarcinoma**. * **Sister Mary Joseph Nodule:** A palpable nodule at the umbilicus representing metastasis from a pelvic or abdominal malignancy (most commonly Stomach CA).
Question 8: What is the most common malignancy found in Marjolin's ulcer?
- A. Basal cell carcinoma (BCC)
- B. Squamous cell carcinoma (SCC) (Correct Answer)
- C. Malignant fibrous histiocytoma
- D. Malignant melanoma
Explanation: **Explanation:** **Marjolin’s ulcer** refers to a malignancy arising in a setting of chronic inflammation, long-standing scars, or non-healing wounds. The most common underlying cause is a **chronic burn scar**, though it can also occur in chronic osteomyelitis sinuses, venous stasis ulcers, and vaccination scars. 1. **Why Squamous Cell Carcinoma (SCC) is correct:** The chronic irritation and repeated cycles of injury and repair in a scar lead to cellular dysplasia. **Squamous cell carcinoma** is the histological diagnosis in approximately **75-90%** of Marjolin’s ulcer cases. These tumors are typically more aggressive, have a higher rate of metastasis (approx. 30%), and carry a poorer prognosis compared to SCC arising in sun-damaged skin. 2. **Why other options are incorrect:** * **Basal Cell Carcinoma (BCC):** While BCC is the most common skin cancer overall, it is the second most common malignancy in Marjolin’s ulcer (approx. 10%). It is less frequent than SCC in the context of chronic scars. * **Malignant Fibrous Histiocytoma & Malignant Melanoma:** These are extremely rare occurrences in chronic scars. While cases have been reported, they do not represent the "most common" malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **Latency Period:** The average time for malignant transformation is **25–30 years**. * **Characteristic Feature:** A Marjolin’s ulcer is characterized by an everted edge, foul-smelling discharge, and rapid growth in a previously stable scar. * **Lymph Nodes:** Unlike typical SCC, Marjolin’s ulcer often bypasses local lymph nodes or presents with late-stage nodal involvement due to the dense fibrotic scar tissue limiting lymphatic drainage. * **Treatment:** Wide local excision (usually with a 2cm margin) or amputation is the treatment of choice.
Question 9: What is a rodent ulcer?
- A. Infectious ulcer
- B. Hypersensitivity
- C. Basal cell carcinoma (Correct Answer)
- D. Squamous cell carcinoma
Explanation: **Explanation:** **Basal Cell Carcinoma (BCC)** is the correct answer. The term **"Rodent Ulcer"** is a classic clinical description for a specific morphological variant of BCC (nodulo-ulcerative type). It is named so because the ulcer appears as if a rodent has "gnawed" into the skin, characterized by a central depression with **pearly, rolled-out borders** and overlying telangiectasia. * **Why it is correct:** BCC arises from the basal layer of the epidermis. While it is locally invasive and can cause significant tissue destruction (hence "ulcer"), it rarely metastasizes. The "rodent ulcer" typically occurs on sun-exposed areas, particularly the upper face (above the line joining the lobe of the ear to the angle of the mouth). * **Why other options are wrong:** * **Infectious ulcers** (e.g., Syphilitic chancre or Cutaneous Leishmaniasis) have distinct microbiological etiologies and different edge characteristics. * **Hypersensitivity** reactions usually present as dermatitis, wheals, or target lesions (Erythema Multiforme), not as chronic destructive ulcers. * **Squamous Cell Carcinoma (SCC)** typically presents as an ulcer with **everted edges** and has a much higher potential for lymphatic metastasis compared to BCC. **High-Yield Clinical Pearls for NEET-PG:** * **Most common** skin cancer globally: Basal Cell Carcinoma. * **Commonest site:** Nose (specifically the ala). * **Histopathology:** Shows "Peripheral Palisading" of nuclei and "Retraction Artifacts." * **Risk Factor:** Chronic UV light exposure and mutations in the **PTCH gene** (Gorlin Syndrome). * **Treatment of choice:** Surgical excision or Mohs Micrographic Surgery (for high-risk sites).
Question 10: What is the most common site for a rodent ulcer?
- A. Limbs
- B. Face (Correct Answer)
- C. Abdomen
- D. Trunk
Explanation: **Explanation:** **Rodent Ulcer** is the clinical eponym for **Basal Cell Carcinoma (BCC)**, the most common skin cancer worldwide. The correct answer is **Face** because BCC primarily arises from the pluripotential cells in the basal layer of the epidermis or hair follicles, and its primary risk factor is chronic, cumulative exposure to **ultraviolet (UV) radiation**. 1. **Why Face is Correct:** Approximately 80–90% of BCCs occur on the head and neck. The face is the most sun-exposed part of the body. Specifically, the most common site is the **upper central part of the face**, particularly above a line joining the angle of the mouth to the ear lobe (e.g., the nose and inner canthus). The term "rodent ulcer" refers to its locally invasive nature, where it appears to "gnaw" through underlying tissue, including bone, if left untreated. 2. **Why Other Options are Incorrect:** * **Limbs, Abdomen, and Trunk:** While BCC can occur on these sites (especially the "Superficial" subtype on the trunk), they are significantly less common than facial involvement. These areas are typically protected by clothing, reducing the cumulative UV dosage compared to the face. **High-Yield Clinical Pearls for NEET-PG:** * **Characteristic Feature:** A pearly, translucent papule with **telangiectasia** (dilated capillaries) and rolled-out borders. * **Metastasis:** BCC is notorious for being **locally invasive** but has an extremely low rate of distant metastasis. * **Risk Factors:** Fair skin (Fitzpatrick types I & II), arsenic exposure, and genetic syndromes like **Gorlin Syndrome** (Nevoid BCC syndrome). * **Treatment of Choice:** Surgical excision; **Mohs Micrographic Surgery** is the gold standard for high-risk facial areas to ensure clear margins while sparing tissue.
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