Skin Tumors — MCQs

Skin Tumors Indian Medical PG Practice Questions and MCQs

Question 141: Becker's nevus is classified as which of the following?

A. Epidermal nevus (Correct Answer)
B. Melanocytic nevus
C. Vascular nevus
D. None of the above

Explanation: **Explanation:** **Becker’s Nevus** (also known as Becker’s melanosis) is classified as an **organoid epidermal nevus**. Despite its name, it is not a true melanocytic lesion but rather a **hamartoma** of ectodermal and mesodermal origin. It is characterized by epidermal hyperplasia (acanthosis), hyperpigmentation of the basal layer, and an increased number of hair follicles. 1. **Why Option A is Correct:** Becker’s nevus is considered a "smooth muscle hamartoma" or a variant of an epidermal nevus because it involves the overgrowth of the epidermis and associated structures (like hair and smooth muscle). It lacks an increased number of melanocytes (nevus cells); instead, it shows increased melanin in the keratinocytes. 2. **Why Option B is Incorrect:** A **Melanocytic nevus** is defined by the proliferation of "nevus cells" (melanocytes). In Becker’s nevus, the number of melanocytes is usually normal or only slightly increased; the dark color is due to hyperpigmentation of the epidermis. 3. **Why Option C is Incorrect:** **Vascular nevi** (like Port-wine stains or hemangiomas) arise from blood vessel abnormalities. Becker’s nevus has no primary vascular component. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Typically appears in adolescent males as a unilateral, hyperpigmented, hairy (hypertrichosis) patch, most commonly on the **shoulder, upper chest, or back**. * **Androgen Sensitivity:** It is androgen-dependent, which explains its development during puberty and the associated hair growth. * **Becker’s Nevus Syndrome:** If associated with underlying structural abnormalities like **ipsilateral breast hypoplasia** or skeletal defects (scoliosis), it is termed Becker’s Nevus Syndrome. * **Histology:** Shows acanthosis, papillomatosis, and often an increase in **arrector pili muscles** (smooth muscle hamartoma).

Question 142: Which of the following is the commonest site for a rodent ulcer?

A. Lips
B. Outer canthus of eye
C. Inner canthus of eye (Correct Answer)
D. Cheek

Explanation: **Explanation:** **Rodent Ulcer** is the clinical term for a slow-growing, locally invasive **Basal Cell Carcinoma (BCC)**. It is the most common skin cancer in humans, typically occurring on sun-exposed areas in elderly individuals. **Why Inner Canthus is Correct:** BCC has a strong predilection for the face, specifically above the line joining the lobe of the ear to the angle of the mouth (the "embryonic fusion lines"). The **inner canthus of the eye** is the most common specific site for a rodent ulcer. This area is particularly dangerous because the tumor can invade deeply into the orbit or the lacrimal system if not treated early. **Analysis of Incorrect Options:** * **Lips (A):** The lower lip is a classic site for **Squamous Cell Carcinoma (SCC)**, not BCC. BCC rarely affects the mucosal surfaces or the vermilion border of the lips. * **Outer Canthus (B):** While BCC can occur here, it is statistically less frequent than the inner canthus. * **Cheek (D):** The cheeks are a common site for various skin tumors, including BCC and SCC, but they do not represent the "most common" specific anatomical site for a rodent ulcer compared to the inner canthus. **High-Yield Clinical Pearls for NEET-PG:** * **Characteristic Feature:** A pearly, translucent border with **telangiectasia** (dilated capillaries) and a central "punched-out" ulcer. * **Metastasis:** BCC is notorious for being **locally aggressive** but rarely metastasizes (unlike SCC or Melanoma). * **Risk Factors:** Chronic UV exposure and arsenic poisoning. * **Pathology:** Histology shows "palisading" of nuclei at the periphery of tumor nests. * **Treatment of Choice:** Wide local excision or **Mohs Micrographic Surgery** (highest cure rate).

Question 143: Which cells are responsible for basal cell carcinoma?

A. Melanocytes
B. Epidermal cells (Correct Answer)
C. Merkel's cells
D. Dermal cells

Explanation: **Explanation:** **Basal Cell Carcinoma (BCC)** is the most common skin cancer worldwide. It originates from the **non-keratinizing cells of the basal layer of the epidermis**. Specifically, these cells are pluripotent epidermal cells located along the basal layer and the follicular bulge of the outer root sheath of the hair follicle. Because it arises from the epithelial lining of the skin, it is classified as an epidermal tumor. **Analysis of Options:** * **Option B (Correct):** BCC arises from the basal layer of the **epidermis**. These cells are responsible for the characteristic "palisading" appearance seen on histopathology. * **Option A (Incorrect):** **Melanocytes** are pigment-producing cells located in the basal layer. Malignant transformation of these cells leads to **Melanoma**, not BCC. * **Option C (Incorrect):** **Merkel cells** are neuroendocrine cells of the skin. Their malignancy results in **Merkel Cell Carcinoma**, a rare but highly aggressive neuroendocrine tumor. * **Option D (Incorrect):** **Dermal cells** (like fibroblasts or endothelial cells) give rise to sarcomas or vascular tumors (e.g., Dermatofibrosarcoma Protuberans or Kaposi Sarcoma), not carcinomas. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Site:** Face (specifically above the line joining the lobe of the ear to the angle of the mouth). * **Characteristic Feature:** "Pearly" or "translucent" papule with **telangiectasia** and a "rolled-out" border. * **Histopathology:** Nests of basaloid cells showing **peripheral palisading** and **retraction artifacts** (clefting). * **Behavior:** Locally invasive ("Rodent ulcer") but **rarely metastasizes**. * **Risk Factor:** Chronic UV radiation exposure and mutations in the **PTCH1 gene** (Hedgehog signaling pathway).

Question 144: Which is an aggressive type of cutaneous T-cell lymphoma?

A. Mycosis Fungoides
B. Sezary syndrome (Correct Answer)
C. Reticulum cell sarcoma
D. Panniculitis

Explanation: **Explanation:** Cutaneous T-cell Lymphomas (CTCL) are a heterogeneous group of extranodal non-Hodgkin lymphomas. The correct answer is **Sezary Syndrome (SS)** because it represents the leukemic, aggressive phase of CTCL. **1. Why Sezary Syndrome is correct:** Unlike Mycosis Fungoides, which is often indolent and skin-limited for years, Sezary Syndrome is characterized by a triad of **erythroderma** (generalized redness), **lymphadenopathy**, and the presence of **Sezary cells** (atypical T-cells with cerebriform nuclei) in the peripheral blood. It carries a significantly poorer prognosis with a median survival of approximately 2–4 years. **2. Why the other options are incorrect:** * **Mycosis Fungoides (MF):** This is the most common CTCL. It typically follows a slow, indolent course progressing through patch, plaque, and tumor stages over decades. * **Reticulum cell sarcoma:** This is an obsolete term formerly used to describe various high-grade lymphomas (now mostly classified under Diffuse Large B-cell Lymphoma). It is not a specific primary cutaneous T-cell lymphoma subtype. * **Panniculitis:** This is an inflammatory condition of the subcutaneous fat (e.g., Erythema Nodosum), not a primary malignancy, although "Subcutaneous panniculitis-like T-cell lymphoma" is a rare malignant variant. **Clinical Pearls for NEET-PG:** * **Pautrier’s Microabscess:** Pathognomonic histological feature of MF/SS (clusters of atypical T-cells in the epidermis). * **Immunophenotype:** Most CTCLs are **CD4+** (Helper T-cells). * **Diagnosis of SS:** Requires an absolute Sezary cell count of **≥1000 cells/mm³**. * **Treatment:** Early-stage MF uses skin-directed therapies (PUVA, topical steroids), while SS requires systemic therapy (Extracorporeal Photopheresis, Interferon-alpha).

Question 145: Which of the following is NOT a sign of internal malignancy?

A. Tuberous sclerosis
B. Acanthosis nigricans
C. Clubbing
D. None of the above (Correct Answer)

Explanation: This question tests the ability to recognize **paraneoplastic syndromes** and cutaneous markers of systemic disease. The correct answer is **None of the above** because all three listed options can serve as clinical indicators of an underlying internal malignancy. ### **Explanation of Options:** * **Acanthosis Nigricans (Option B):** While most commonly associated with insulin resistance and obesity, the **malignant type** of Acanthosis Nigricans (often sudden onset, extensive, and involving the palms/mucosa) is a classic sign of internal malignancy, most frequently **Gastric Adenocarcinoma**. * **Clubbing (Option C):** Digital clubbing is a well-recognized sign of systemic pathology. In the context of malignancy, it is most strongly associated with **Bronchogenic Carcinoma** and other thoracic tumors. It often presents as part of Hypertrophic Osteoarthropathy (HOA). * **Tuberous Sclerosis (Option A):** This is a neurocutaneous syndrome (phakomatosis) caused by mutations in TSC1 or TSC2 genes. It is characterized by the development of benign tumors in multiple organs; however, it significantly increases the risk of specific internal malignancies, most notably **Renal Cell Carcinoma (RCC)**. ### **Clinical Pearls for NEET-PG:** * **Leser-Trélat Sign:** The sudden eruption of multiple seborrheic keratoses; a high-yield marker for internal malignancy (usually GI tract). * **Tripe Palms:** Velvety hyperkeratosis of the palms, often associated with lung or gastric cancer. * **Sweet Syndrome:** Acute febrile neutrophilic dermatosis; can be a marker for **Acute Myeloid Leukemia (AML)**. * **Dermatomyositis:** In adults, this inflammatory myopathy is a paraneoplastic marker in up to 20-25% of cases (check for breast, lung, or ovarian cancer).

Question 146: Which of the following is a marker for malignant melanoma?

A. Cytokeratin
B. MBN-45
C. Alpha FP
D. S-100 (Correct Answer)

Explanation: **Explanation:** **Malignant Melanoma** is a neoplasm arising from melanocytes, which are cells derived from the **neural crest**. Understanding the embryological origin and protein expression of these cells is key to identifying their immunohistochemical (IHC) markers. **Why S-100 is the Correct Answer:** **S-100** is a calcium-binding protein found in cells derived from the neural crest (melanocytes, Schwann cells, glial cells). It is considered the **most sensitive marker** for malignant melanoma. While it lacks high specificity (as it also stains nerve sheath tumors and some carcinomas), it is the primary screening tool used by pathologists to rule out melanoma. **Analysis of Incorrect Options:** * **A. Cytokeratin:** This is a marker for epithelial cells. It is used to identify **Carcinomas** (e.g., Squamous Cell Carcinoma). Melanomas are typically cytokeratin-negative. * **B. MBN-45:** This is likely a distractor or a typo for **HMB-45** (Human Melanoma Black-45). While HMB-45 is a highly specific marker for melanoma, S-100 remains the standard "classic" answer for general sensitivity in exams. * **C. Alpha FP (Alpha-Fetoprotein):** This is a tumor marker for **Hepatocellular Carcinoma** and certain germ cell tumors (Yolk sac tumors), with no relevance to melanocytic lesions. **NEET-PG High-Yield Pearls:** * **Most Sensitive Marker:** S-100. * **Most Specific Markers:** HMB-45 and Melan-A (MART-1). * **Newer Marker:** SOX-10 (highly sensitive and specific for melanocytic differentiation). * **Prognostic Factor:** **Breslow’s Thickness** (vertical depth in mm) is the most important prognostic factor for cutaneous melanoma. * **Common Mutation:** **BRAF V600E** mutation is frequently seen in non-acral cutaneous melanomas.

Question 147: Langerhans cells are not seen in which of the following conditions?

A. Letterer-Siwe disease
B. Fabry disease (Correct Answer)
C. Histiocytosis
D. None of the above

Explanation: **Explanation:** The question tests your ability to differentiate between disorders of histiocytic proliferation and metabolic storage diseases. **Why Fabry Disease is the Correct Answer:** **Fabry disease** is an X-linked recessive **lysosomal storage disorder** caused by a deficiency of the enzyme **alpha-galactosidase A**. This leads to the systemic accumulation of globotriaosylceramide (Gb3) in vascular endothelium and other tissues. It is characterized clinically by angiokeratomas, acroparesthesia, hypohidrosis, and renal/cardiac failure. It does **not** involve the proliferation or presence of Langerhans cells. **Analysis of Incorrect Options:** * **Letterer-Siwe Disease:** This is the acute disseminated form of **Langerhans Cell Histiocytosis (LCH)**, typically seen in infants. It involves multi-organ proliferation of Langerhans cells (CD1a+, S100+, and CD207+). * **Histiocytosis:** This is a broad term for a group of syndromes characterized by the proliferation of histiocytes. Specifically, **Langerhans Cell Histiocytosis (LCH)** is the prototypical condition where these cells are the primary pathological finding. **High-Yield Clinical Pearls for NEET-PG:** * **Langerhans Cells (LCs):** These are dendritic, antigen-presenting cells located in the **Stratum Spinosum** of the epidermis. * **Electron Microscopy Gold Standard:** The presence of **Birbeck Granules** (tennis-racket shaped organelles) is pathognomonic for Langerhans cells. * **Immunohistochemistry (IHC) Markers:** LCs are positive for **S-100**, **CD1a**, and **Langerin (CD207)**. * **Fabry Disease "Mnemonic":** Remember "The **Fabry** **Alpha** male **Gal** acts **X-linked**" (Alpha-galactosidase A deficiency, X-linked inheritance). Look for "Maltese cross" appearance in urinary sediment.

Question 148: A 69-year-old woman develops dark, velvety pigmentation in her axillae. She has noticed 10 lb weight loss over the past 3 months with heartburn and early satiety. She notices no other symptoms. Which of the following conditions should be investigated?

A. A visceral carcinoma (Correct Answer)
B. Lymphoma
C. Diabetes mellitus
D. Sarcoidosis

Explanation: **Explanation:** The clinical presentation describes **Acanthosis Nigricans (AN)**, characterized by dark, velvety, hyperpigmented plaques in intertriginous areas like the axillae and neck. While AN is most commonly associated with insulin resistance, the presence of **"red flag" symptoms**—advanced age (69 years), rapid onset, and systemic signs (10 lb weight loss, early satiety, heartburn)—strongly points toward **Malignant Acanthosis Nigricans**. 1. **Why A is correct:** Malignant AN is a paraneoplastic syndrome. In approximately 90% of cases, it is associated with an intra-abdominal malignancy, most commonly **Gastric Adenocarcinoma** (explaining the patient's heartburn and early satiety). Unlike the benign form, malignant AN often appears suddenly, spreads rapidly, and involves the mucosa or palms (tripe palms). 2. **Why B is incorrect:** While lymphomas can cause paraneoplastic skin changes (like exfoliative dermatitis or Ichthyosis acquisita), they are not the classic association for Acanthosis Nigricans. 3. **Why C is incorrect:** Diabetes mellitus and obesity are the most common causes of *Benign* AN (Type II). However, they do not typically present with rapid weight loss or gastric symptoms in an elderly patient. 4. **Why D is incorrect:** Sarcoidosis typically presents with skin findings like Lupus Pernio or erythema nodosum, not velvety hyperpigmentation. **NEET-PG High-Yield Pearls:** * **Most common site for AN:** Posterior neck, followed by axillae. * **Most common malignancy associated:** Gastric Adenocarcinoma (TGF-alpha produced by the tumor is the implicated growth factor). * **Tripe Palms:** Velvety thickening of palmar skin; if seen with AN, it highly suggests internal malignancy (Lung or Gastric). * **Leser-Trélat Sign:** Sudden eruption of multiple seborrheic keratoses; also a paraneoplastic sign often seen alongside malignant AN.

Question 149: Keratoacanthoma is:

A. A type of basal cell carcinoma
B. An infected sebaceous cyst
C. A self-healing nodular lesion with central ulceration (Correct Answer)
D. A pre-malignant disease

Explanation: **Explanation:** **Keratoacanthoma (KA)** is a common, rapidly growing skin tumor that clinically and histologically resembles well-differentiated squamous cell carcinoma (SCC). **Why Option C is correct:** The hallmark of Keratoacanthoma is its unique **triphasic clinical course**: 1. **Proliferative phase:** Rapid growth over 4–6 weeks. 2. **Stationary phase:** Formation of a dome-shaped, skin-colored nodule with a characteristic **central keratinous plug** (crateriform appearance). 3. **Involutional phase:** Spontaneous regression over 6–12 months, often leaving a depressed scar. This "self-healing" nature is its defining feature. **Why other options are incorrect:** * **Option A:** It is not a type of Basal Cell Carcinoma (BCC). While it mimics SCC, BCC presents differently (pearly borders, telangiectasia) and does not regress spontaneously. * **Option B:** An infected sebaceous cyst presents with fluctuance, pain, and purulent discharge, lacking the central keratin plug and rapid symmetrical growth of KA. * **Option D:** It is not "pre-malignant" (like Actinic Keratosis); rather, it is often considered a **low-grade malignancy** or a variant of SCC that happens to regress. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Shows a "cup-shaped" invagination with a central keratin plug and "overhanging edges" (lips) of the epidermis. * **Associations:** Multiple keratoacanthomas are seen in **Ferguson-Smith syndrome** (multiple self-healing) and **Grzybowski syndrome** (generalized eruptive). * **Muir-Torre Syndrome:** Keratoacanthomas associated with internal malignancies (especially GI tract). * **Management:** Despite its self-healing nature, surgical excision is usually the treatment of choice because it is difficult to distinguish from aggressive SCC.

Question 150: Which skin tumor is known as the "Turban tumor"?

A. Basal cell carcinoma
B. Squamous cell carcinoma
C. Cutaneous cylindroma (Correct Answer)
D. Dermatofibroma

Explanation: **Explanation:** **Cutaneous Cylindroma** is the correct answer. It is a benign adnexal tumor originating from the sweat glands (eccrine or apocrine). When multiple cylindromas occur, they typically involve the scalp and can grow large enough to cover the entire cranium like a headpiece, earning the clinical nickname **"Turban tumor."** * **Histology (High Yield):** On biopsy, it shows a characteristic **"Jigsaw puzzle" appearance**, where nests of basaloid cells are surrounded by a thick, eosinophilic, PAS-positive hyaline sheath. * **Genetics:** Multiple cylindromas are associated with **Brooke-Spiegler Syndrome**, an autosomal dominant condition caused by a mutation in the **CYLD gene**. **Why the other options are incorrect:** * **Basal Cell Carcinoma (BCC):** The most common skin cancer, typically presenting as a pearly papule with telangiectasia or a "rodent ulcer," but it does not form a turban-like distribution. * **Squamous Cell Carcinoma (SCC):** Presents as an indurated, scaling plaque or ulcer, often associated with sun exposure or precursor lesions like actinic keratosis. * **Dermatofibroma:** A common benign fibrous nodule, usually found on the legs, characterized by the **"Dimple sign"** (central depression upon lateral pressure). **Clinical Pearls for NEET-PG:** 1. **Cylindroma:** Jigsaw puzzle pattern + CYLD gene + Turban tumor. 2. **Spiradenoma:** Often co-exists with cylindromas in Brooke-Spiegler Syndrome; these are characteristically **painful** skin tumors. 3. **Trichoepithelioma:** Another component of Brooke-Spiegler, presenting as multiple flesh-colored papules in the nasolabial folds.

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Benign Epithelial Tumors

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Premalignant Epidermal Tumors

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Basal Cell Carcinoma

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Squamous Cell Carcinoma

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Melanocytic Nevi

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Melanoma

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Merkel Cell Carcinoma

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Vascular Tumors and Malformations

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Cutaneous Lymphomas

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Soft Tissue Tumors

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Metastatic Skin Tumors

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Skin Cancer Prevention and Screening

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Skin Tumors — MCQs

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