Premalignant skin lesions US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Premalignant skin lesions. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Premalignant skin lesions US Medical PG Question 1: A 60-year-old white man with a past medical history significant for hypertension and hyperlipidemia presents to his family medicine physician with concerns about a 'spot' on his ear. He has been a construction worker for 35 years and spends most of his time outside. His family history is insignificant. On physical examination, there is a dark lesion on his left ear. The patient states that he has always had a mole in this location but that it has recently become much larger. A review of systems is otherwise negative. Which of the following lesion characteristics would be MOST reassuring among the given options?
- A. Single, dark color (Correct Answer)
- B. Changing over time
- C. Lesion asymmetry
- D. Irregular, indistinct borders
Premalignant skin lesions Explanation: ***Single, dark color***
- A **single, uniform dark color** in a mole is a reassuring characteristic, indicating a stable pigmentation pattern, as opposed to multiple colors or shades which are concerning for melanoma [1].
- While the patient notes the mole has grown, a uniform color suggests it has maintained its benign pigment distribution rather than showing chaotic growth patterns [1].
- This is the most reassuring finding among the options presented.
*Changing over time*
- Any **change in an existing mole**, whether in size, shape, color, or elevation (the "E" in ABCDE criteria), is the most significant warning sign for potential malignancy, making it highly concerning [1].
- The patient's statement that the mole has "recently become much larger" directly points to this concerning characteristic [1].
*Lesion asymmetry*
- **Asymmetry** ("A" in ABCDE) means that if you draw a line through the mole, the two halves do not match, which is a key indicator of potential melanoma and is not reassuring [1].
- Benign moles are typically symmetrical.
*Irregular, indistinct borders*
- **Irregular or indistinct borders** ("B" in ABCDE) are a hallmark characteristic of melanoma, as malignant cells tend to invade surrounding tissue in an uneven manner [1].
- Benign moles usually have smooth, well-defined borders.
Premalignant skin lesions US Medical PG Question 2: A 57-year-old post-menopausal woman comes to the physician because of intermittent, bloody post-coital vaginal discharge for the past month. She does not have pain with intercourse. Eleven years ago, she had LSIL on a routine Pap smear and testing for high-risk HPV strains was positive. Colposcopy showed CIN 1. She has not returned for follow-up Pap smears since then. She is sexually active with her husband only, and they do not use condoms. She has smoked half a pack of cigarettes per day for the past 25 years and does not drink alcohol. On speculum exam, a 1.4 cm, erythematous exophytic mass with ulceration is noted on the posterior wall of the upper third of the vagina. Which of the following is the most probable histopathology of this mass?
- A. Basal cell carcinoma
- B. Melanoma
- C. Adenocarcinoma
- D. Sarcoma botryoides
- E. Squamous cell carcinoma (Correct Answer)
Premalignant skin lesions Explanation: ***Squamous cell carcinoma***
- The patient's history of **LSIL** with **high-risk HPV** and **non-adherence to follow-up Pap smears** strongly suggests a progression to squamous cell carcinoma.
- **Smoking** is a significant risk factor for SCC, and the description of an **erythematous exophytic mass with ulceration** is consistent with this diagnosis.
*Basal cell carcinoma*
- This is a common skin cancer, but it is **extremely rare in the vagina**, typically occurring in sun-exposed areas.
- While it can manifest as an ulcerated lesion, the risk factors and location do not align with this patient's presentation.
*Melanoma*
- Although **vaginal melanoma** can occur, it is rare and typically presents as a **pigmented lesion**, which is not described.
- The patient's risk factors (HPV, smoking) are not primary drivers of melanoma development.
*Adenocarcinoma*
- **Vaginal adenocarcinoma** is rare and often associated with **diethylstilbestrol (DES) exposure** in utero, which is absent in this case.
- While an exophytic mass can occur, the strong history of **HPV-related dysplasia** points away from adenocarcinoma.
*Sarcoma botryoides*
- This is a rare form of **rhabdomyosarcoma** and typically presents in **infants and young children** as a grapelike mass protruding from the vagina.
- It is not seen in post-menopausal women and is histologically distinct from the likely HPV-related malignancy.
Premalignant skin lesions US Medical PG Question 3: A 52-year-old Caucasian man presents to the clinic for evaluation of a mole on his back that he finds concerning. He states that his wife noticed the lesion and believes that it has been getting larger. On inspection, the lesion is 10 mm in diameter with irregular borders. A biopsy is performed. Pathology reveals abnormal melanocytes forming nests at the dermo-epidermal junction and discohesive cell growth into the epidermis. What is the most likely diagnosis?
- A. Desmoplastic melanoma
- B. Lentigo maligna melanoma
- C. Superficial spreading melanoma (Correct Answer)
- D. Nodular melanoma
- E. Acral lentiginous melanoma
Premalignant skin lesions Explanation: ***Superficial spreading melanoma***
- This is the **most common type of melanoma**, accounting for 70% of cases, and typically presents with a **radial growth phase** showing irregular borders and enlarging size.
- Histopathology revealing **nests of abnormal melanocytes at the dermo-epidermal junction** and **discohesive cell growth into the epidermis** (pagetoid spread) is characteristic of superficial spreading melanoma.
*Desmoplastic melanoma*
- Characterized by **fibrous stroma** and often **neural invasion**, with a less pigmented appearance, which is not described.
- Typically presents as a firm, often amelanotic nodule, and can be more aggressive.
*Lentigo maligna melanoma*
- Primarily found in **chronically sun-damaged areas** of the elderly, often on the face, and begins as a flat, tan-brown macule that slowly enlarges.
- Histologically, it shows **atypical melanocytes along the basal layer** of a thinned epidermis, not necessarily forming nests or extensive discohesive growth into the epidermis early on.
*Nodular melanoma*
- This type of melanoma has a **vertical growth phase from the outset**, appearing as a rapidly growing, dark, elevated lesion without a significant preceding radial growth phase.
- Histologically, it involves a substantial dermal component with **minimal or absent intraepidermal radial growth**.
*Acral lentiginous melanoma*
- Occurs on the **palms, soles, or under the nails (subungual)**, and is less associated with sun exposure, often presenting as a dark, spreading lesion.
- Its histological features involve **lentiginous proliferation of atypical melanocytes** along the dermo-epidermal junction with spread into the rete ridges in an acral distribution.
Premalignant skin lesions US Medical PG Question 4: A 34-year-old man presents to the office for evaluation of a lesion on his upper arm that appeared a few months ago and has not healed. The patient appears healthful but has a history of cardiovascular disease. He states that his friend at the industrial ammunition factory where he works told him he should "get it looked at." The patient admits to some nausea, vomiting, and diarrhea over the past year, but he states that he "feels fine now." On physical examination, the lesion is an erythematous, scaly, ulcerated plaque on the flexor surface of his upper arm. The rest of the exam is within normal limits. What is the most likely diagnosis?
- A. Squamous cell carcinoma (SCC) (Correct Answer)
- B. Erythema multiforme
- C. Actinic keratosis
- D. Erysipelas
- E. Contact dermatitis
Premalignant skin lesions Explanation: ***Squamous cell carcinoma (SCC)***
- The patient's occupational exposure to chemicals at an **ammunition factory**, along with chronic non-healing, **ulcerated, scaly plaque**, raises suspicion for SCC, particularly **arsenic-induced SCC**.
- His history of vague **gastrointestinal symptoms** (nausea, vomiting, diarrhea) over the past year is also consistent with **chronic arsenic exposure**, which is a known carcinogen.
*Erythema multiforme*
- This is an **acute, self-limiting hypersensitivity reaction** to medications or infections, characterized by target lesions, not a chronic, non-healing ulcerated plaque.
- It would not typically present with a history of chronic GI symptoms related to occupational exposure.
*Actinic keratosis*
- This is a **precancerous lesion** caused by chronic sun exposure, typically presenting as a rough, scaly patch on sun-exposed areas.
- While it has malignant potential to transform into SCC, the description of an **ulcerated, non-healing lesion** with a history of probable chemical exposure makes SCC a more likely *current* diagnosis.
*Erysipelas*
- Erysipelas is a **superficial bacterial infection** of the skin characterized by a rapidly spreading, bright red, well-demarcated, and painful rash, often accompanied by fever and systemic symptoms.
- It would not manifest as a chronic, non-healing ulcerated plaque over several months.
*Contact dermatitis*
- This is an **inflammatory skin reaction** due to direct contact with an allergen or irritant, typically presenting as an itchy, erythematous rash with vesicles or papules.
- It would not typically result in a chronic, ulcerated, non-healing plaque and is not associated with the systemic symptoms or occupational exposure history presented.
Premalignant skin lesions US Medical PG Question 5: A 74-year-old man comes to the physician for evaluation of a skin lesion on his right arm. The lesion first appeared 3 months ago and has since been slowly enlarging. Physical examination shows a 1.5-centimeter, faintly erythematous, raised lesion with irregular borders on the dorsum of the right forearm. A biopsy specimen is obtained. If present, which of the following histopathological features would be most consistent with carcinoma in situ?
- A. Presence of epithelial cells in the dermis
- B. Pleomorphism of cells in the stratum corneum
- C. Increased nuclear to cytoplasmic ratio in the stratum spinosum
- D. Full-thickness basal to apical cell polarity
- E. Full-thickness nuclear atypia with intact basement membrane (Correct Answer)
Premalignant skin lesions Explanation: ***Full-thickness nuclear atypia with intact basement membrane***
- Carcinoma in situ (CIS) is characterized by **malignant changes confined to the epidermis** with **full-thickness involvement** of all viable epidermal layers.
- The **basement membrane remains intact**, meaning there is no invasion into the dermis.
- **Nuclear atypia, loss of maturation, and architectural disarray** extend from the basal layer to the superficial layers, but cancerous cells have not breached the basement membrane.
- This describes **Bowen's disease** (squamous cell carcinoma in situ), which is consistent with the clinical presentation of a slowly enlarging erythematous plaque on sun-exposed skin in an elderly patient.
*Presence of epithelial cells in the dermis*
- The presence of **epithelial cells in the dermis** indicates **invasive squamous cell carcinoma**, as it signifies breach of the basement membrane.
- Carcinoma in situ, by definition, is restricted to the **epidermis** and does not involve dermal invasion.
*Pleomorphism of cells in the stratum corneum*
- The **stratum corneum** consists of dead, anucleated keratinocytes, making nuclear **pleomorphism** impossible in this layer.
- Malignant changes occur in the **viable layers of the epidermis** (stratum basale, spinosum, granulosum), not in the cornified layer.
*Increased nuclear to cytoplasmic ratio in the stratum spinosum*
- While an **increased nuclear-to-cytoplasmic ratio** is seen in carcinoma in situ, this option implies changes limited to the stratum spinosum only.
- True carcinoma in situ requires **full-thickness** epidermal involvement, not changes confined to a single layer.
- Changes limited to one layer would suggest **dysplasia** rather than carcinoma in situ.
*Full-thickness basal to apical cell polarity*
- This describes **normal epidermal architecture** with ordered maturation of keratinocytes from basal to superficial layers.
- In carcinoma in situ, this **normal polarity is lost**, with architectural disarray and loss of orderly maturation throughout the epidermis.
Premalignant skin lesions US Medical PG Question 6: A 43-year-old woman presents to your clinic for the evaluation of an abnormal skin lesion on her forearm. The patient is worried because her mother passed away from melanoma. You believe that the lesion warrants biopsy for further evaluation for possible melanoma. Your patient is concerned about her risk for malignant disease. What is the most important prognostic factor of melanoma?
- A. Depth of invasion of atypical cells (Correct Answer)
- B. S-100 tumor marker present
- C. Evolution of lesion over time
- D. Age at presentation
- E. Level of irregularity of the borders
Premalignant skin lesions Explanation: ***Depth of invasion of atypical cells***
- The **Breslow depth**, which measures the vertical thickness of the melanoma from the granular layer of the epidermis to the deepest part of the tumor, is the **single most important prognostic factor** for localized melanoma.
- A greater depth of invasion correlates directly with a higher risk of **metastasis** and a poorer prognosis due to increased likelihood of reaching dermal lymphatics or blood vessels.
*S-100 tumor marker present*
- While **S-100 protein** is a marker expressed in melanoma cells and can be used to detect metastatic disease (e.g., in lymph nodes), its mere presence does not serve as the primary prognostic indicator for the primary lesion itself.
- S-100 reflects the presence of melanoma cells but does not provide information about the **depth or biological aggressiveness** of the initial tumor.
*Evolution of lesion over time*
- The **evolution or change** in a lesion (e.g., in size, shape, color, new symptoms) is a crucial diagnostic criterion for identifying suspicious lesions for biopsy.
- While important for diagnosis, it is not a direct prognostic factor once melanoma is confirmed; the **pathological features** after biopsy, particularly depth, determine prognosis.
*Age at presentation*
- **Age** can influence treatment decisions and overall health status, but it is not the most important independent prognostic factor for melanoma.
- Prognosis is primarily driven by tumor-specific characteristics rather than the patient's age.
*Level of irregularity of the borders*
- **Border irregularity** is one of the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving) used to identify suspicious pigmented lesions.
- It is a diagnostic indicator that warrants further investigation but does not independently determine **prognosis** as definitively as the Breslow depth after biopsy.
Premalignant skin lesions US Medical PG Question 7: A 52-year-old man presents with a rapidly growing, dome-shaped nodule on his right arm that developed over 6 weeks. Examination reveals a 2 cm, symmetrical, crateriform nodule with a central keratin plug. Which of the following is the most likely diagnosis?
- A. Keratoacanthoma (Correct Answer)
- B. Squamous cell carcinoma
- C. Basal cell carcinoma
- D. Melanoma
Premalignant skin lesions Explanation: ***Keratoacanthoma***
- The rapid growth over 6 weeks and the classic description of a **dome-shaped, crateriform nodule with a central keratin plug** are highly characteristic of a keratoacanthoma.
- While histologically similar to well-differentiated squamous cell carcinoma, its distinct clinical presentation with spontaneous regression potential often differentiates it.
*Squamous cell carcinoma*
- Although it can present as a nodule, it typically exhibits slower growth and is less likely to have the classic **crateriform shape with a central keratin plug** that rapidly evolves over weeks.
- Aggressive types can grow rapidly but often present with ulceration or induration rather than the specific dome-shaped morphology described.
*Basal cell carcinoma*
- Usually presents as a **pearly nodule** with telangiectasias, often with a rolled border, and grows slowly over months to years.
- It lacks the characteristic **crateriform appearance** and rapid growth seen in this case.
*Melanoma*
- Characterized by asymmetry, irregular borders, varied colors, and a diameter greater than 6 mm (ABCDEs).
- While some nodular melanomas can grow rapidly, they typically lack the distinct **crateriform morphology** and central keratin plug.
Premalignant skin lesions US Medical PG Question 8: A 61-year-old man with a past medical history significant for asthma and psoriasis presents to the clinic for a wellness visit. He has no specific complaints. The patient’s blood pressure is 121/73 mm Hg, the pulse is 81/min, the respiratory rate is 16/min, and the temperature is 37.2°C (99.1°F). Physical examination reveals a 3.3 cm (1.2 in) lesion overlying his left elbow with an erythematous border, covered with a silver scale. What type of lesion is on the patient’s elbow?
- A. Patch
- B. Lichenification
- C. Papule
- D. Plaque (Correct Answer)
- E. Excoriation
Premalignant skin lesions Explanation: ***Plaque***
- A **plaque** is a **solid, elevated lesion** greater than 1 cm in diameter, often formed by the coalescence of papules.
- The description of a 3.3 cm lesion with an erythematous border and silver scale, in a patient with **psoriasis**, is classic for a psoriatic plaque.
*Patch*
- A **patch** is a large, **flat discoloration** (>1 cm) of the skin that is not elevated or depressed.
- The described lesion is elevated and palpable, which distinguishes it from a patch.
*Lichenification*
- **Lichenification** refers to a **thickening of the skin** with exaggerated normal skin lines, usually due to chronic scratching or rubbing.
- While associated with chronic skin conditions, the described lesion's size and scaly appearance do not fit the definition of lichenification.
*Papule*
- A **papule** is a **solid, elevated lesion** that is less than 1 cm in diameter.
- The lesion described is 3.3 cm, making it too large to be classified as a papule.
*Excoriation*
- An **excoriation** is a **linear break in the skin** surface, often caused by scratching.
- The described lesion is a raised, scaly patch, not a break in the skin from scratching.
Premalignant skin lesions US Medical PG Question 9: A 35-year-old woman with no significant past medical, past surgical, family or social history presents to clinic with a recently identified area of flat, intact, pigmented skin. The patient believes that this is a large freckle, and she states that it becomes darker during the summer when she is outdoors. On physical examination, you measure the lesion to be 6 mm in diameter. Which of the following is the best descriptor of this patient’s skin finding?
- A. Wheal
- B. Papule
- C. Ulcer
- D. Plaque
- E. Macule (Correct Answer)
Premalignant skin lesions Explanation: ***Macule***
- A **macule** is a **flat, discolored lesion** that is less than 1 cm in diameter, which fits the description of a **flat, pigmented skin area** that is 6 mm in diameter.
- The darkening of the lesion with sun exposure is characteristic of a **freckle**, which is a type of macule caused by increased melanin production without an increase in melanocyte numbers.
*Wheal*
- A **wheal** is a **transient, elevated lesion** caused by dermal edema, typically seen in allergic reactions like hives.
- This patient's lesion is described as a **flat, pigmented area**, not an elevated, transient swelling.
*Papule*
- A **papule** is a **solid, elevated lesion** that is less than 1 cm in diameter.
- The patient's skin finding is explicitly described as **flat** and intact, not elevated.
*Ulcer*
- An **ulcer** is a **loss of epidermis and dermis**, resulting in an open sore; it is not a flat, intact pigmented lesion.
- The description of the lesion as **intact** rules out an ulcer, which involves a break in the skin surface.
*Plaque*
- A **plaque** is a **flat-topped, elevated lesion** that is larger than 1 cm in diameter.
- While flat-topped, a plaque is **elevated**, and the patient's lesion is described as **flat**, not elevated.
Premalignant skin lesions US Medical PG Question 10: A 72-year-old man comes to the physician because of a lesion on his eyelid for 6 months. The lesion is not painful or pruritic. He initially dismissed it as a 'skin tag' but the lesion has increased in size over the past 3 months. He has type 2 diabetes mellitus, coronary artery disease, and left hemiplegia from a stroke 3 years ago. Current medications include sitagliptin, metformin, aspirin, and simvastatin. He used to work as a construction contractor and retired 3 years ago. Examination shows a 1-cm (0.4-in) flesh-colored, nodular, nontender lesion with rolled borders. There is no lymphadenopathy. Cardiopulmonary examination shows no abnormalities. Muscle strength is reduced in the left upper and lower extremities. Visual acuity is 20/20. The pupils are equal and reactive to light. A shave biopsy confirms the diagnosis of basal cell carcinoma. Which of the following is the most appropriate next step in management?
- A. Laser ablation
- B. Cryotherapy
- C. Topical chemotherapy
- D. Wide local excision
- E. Mohs micrographic surgery (Correct Answer)
Premalignant skin lesions Explanation: ***Mohs micrographic surgery***
- The lesion's location on the **eyelid** (a cosmetically and functionally sensitive area), its **nodular appearance** with **rolled borders**, and the likely diagnosis of **basal cell carcinoma (BCC)** make Mohs surgery the most appropriate treatment.
- Mohs surgery offers the highest cure rates for BCCs and preserves the maximum amount of healthy tissue, which is crucial for lesions on the face and eyelids.
*Wide local excision*
- While effective for many skin cancers, **wide local excision** might lead to significant cosmetic or functional defects on the eyelid due to the need for a wider margin of healthy tissue removal.
- Its cure rates are generally lower than Mohs surgery for high-risk BCCs, especially in sensitive areas.
*Laser ablation*
- **Laser ablation** is typically used for superficial or precancerous lesions, not for nodular, invasive basal cell carcinoma.
- It does not allow for histological margin control, which is essential to ensure complete tumor removal and reduce recurrence.
*Cryotherapy*
- **Cryotherapy** is suitable for small, superficial, or pre-malignant lesions, but not for a nodular lesion on the eyelid where tissue preservation and precise margin control are critical.
- It does not offer histological confirmation of clear margins, increasing the risk of recurrence.
*Topical chemotherapy*
- **Topical chemotherapy** (e.g., imiquimod, 5-fluorouracil) is generally reserved for superficial basal cell carcinomas distant from critical structures.
- It is not effective for nodular BCCs and lacks the ability to confirm complete tumor removal via microscopic margin assessment.
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