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 66-year-old man presents to his family physician complaining of a sandpaper-like sensation when he touches the lesion on his forehead. His medical history is relevant for hypertension and hypercholesterolemia, for which he is taking losartan and atorvastatin. He used to work as a gardener, but he retired 3 years ago. His vital signs are within normal limits. Physical examination of his forehead reveals male-pattern baldness and thin, adherent, yellow-colored skin lesions that feel rough to the touch (see image). His family physician refers to him to a dermatologist for further management and treatment. Which of the following conditions would the patient most likely develop if this skin condition is left untreated?
- A. Squamous cell carcinoma (Correct Answer)
- B. Mycosis fungoides
- C. Seborrheic keratosis
- D. Actinic cheilitis
- E. Basal cell carcinoma
Premalignant skin lesions Explanation: ***Squamous cell carcinoma***
- The description of a **rough, sandpaper-like, yellow-colored lesion** on a sun-exposed area like the forehead, in a patient with a history of outdoor work (gardener), is highly characteristic of **actinic keratosis**.
- **Actinic keratosis** is a premalignant lesion that can progress to **invasive squamous cell carcinoma** if left untreated.
*Mycosis fungoides*
- This is a form of **cutaneous T-cell lymphoma** and typically presents as patches, plaques, or tumors that are often pruritic.
- It does not present as a rough, sandpaper-like lesion and is not directly associated with sun exposure in the same way as actinic keratosis.
*Seborrheic keratosis*
- Seborrheic keratoses are **benign epidermal tumors** that appear as "stuck-on" lesions, often waxy or greasy, and can be various shades of brown or black.
- While they can be rough, they are typically not described as "sandpaper-like" and do not carry the risk of malignant transformation like actinic keratosis.
*Actinic cheilitis*
- **Actinic cheilitis** is a variant of actinic keratosis that specifically affects the **lips**, primarily the lower lip, due to chronic sun exposure.
- While also premalignant and able to progress to squamous cell carcinoma, the lesion described in the question is on the **forehead**, not the lips.
*Basal cell carcinoma*
- **Basal cell carcinoma (BCC)** is another common skin cancer linked to sun exposure, but it typically presents as a **pearly nodule**, often with rolled borders and telangiectasias, or as a superficial red patch.
- While BCC can develop in sun-exposed areas, actinic keratosis is a direct precursor to squamous cell carcinoma, not basal cell carcinoma.
Premalignant skin lesions US Medical PG Question 7: 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 8: 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 9: An otherwise healthy 17-year-old girl comes to the physician because of multiple patches on her face, hands, abdomen, and feet that are lighter than the rest of her skin. The patches began to appear 3 years ago and have been gradually increasing in size since. There is no associated itchiness, redness, numbness, or pain. She emigrated from India 2 years ago. An image of the lesions on her face is shown. Which of the following is most likely involved in the pathogenesis of this patient's skin findings?
- A. Defective tuberin protein
- B. Infection with Malassezia globosa
- C. Infection with Mycobacterium leprae
- D. Absence of tyrosinase activity
- E. Autoimmune destruction of melanocytes (Correct Answer)
Premalignant skin lesions Explanation: ***Autoimmune destruction of melanocytes***
- The presentation of **multiple, gradually enlarging hypopigmented patches** on various body areas, particularly in an otherwise healthy individual, is highly suggestive of **vitiligo**.
- **Vitiligo** is an acquired depigmentation disorder resulting from the **autoimmune destruction of melanocytes**, leading to a complete absence of melanin in the affected areas.
*Defective tuberin protein*
- **Defective tuberin protein** is associated with **tuberous sclerosis**, a neurocutaneous syndrome.
- Skin manifestations of tuberous sclerosis include **ash-leaf spots** (hypopigmented macules), **facial angiofibromas**, and **Shagreen patches**, which are typically present from birth or early childhood and often associated with neurological symptoms.
*Infection with Malassezia globosa*
- **Malassezia globosa** causes **tinea versicolor** (pityriasis versicolor), a superficial fungal infection characterized by **hypopigmented or hyperpigmented patches** with fine scale.
- These lesions often occur on the trunk and proximal extremities and typically **fluoresce yellow-green** under Wood's lamp, which is not mentioned here.
*Infection with Mycobacterium leprae*
- **Mycobacterium leprae** causes **leprosy**, which can present with **hypopigmented macules** that are typically **anesthetic** (loss of sensation).
- While the patient is from an endemic area (India), the lack of **anesthesia**, associated neuropathic symptoms, or active inflammation makes leprosy less likely.
*Absence of tyrosinase activity*
- **Absence of tyrosinase activity** is characteristic of **oculocutaneous albinism**, a *genetic* condition leading to a *generalized lack of pigmentation* in the skin, hair, and eyes.
- This patient presents with *localized patches* of depigmentation that appeared at 14 years old, which is inconsistent with congenital albinism.
Premalignant skin lesions US Medical PG Question 10: A 62-year-old man seeks evaluation at an outpatient clinic for a single, red, crusty lesion on the shaft of his penis and a similar lesion on the middle finger of his left hand. He recently immigrated to the US from Africa. The lesions are painless and the physicians in his country treated him for syphilis and eczema, with no improvement. He lives with his 4th wife. He smokes 2 packs of cigarette per day and has been doing so for the last 30 years. He is not aware of any family members with malignancies or hereditary diseases. The physical examination is remarkable for an erythematous plaque, with areas of crusting, oozing, and irregular borders on the dorsal surface of the penile shaft and a similar lesion on his left middle finger (shown in the picture). The regional lymph nodes are not affected. A biopsy is obtained and the pathologic evaluation reveals cells with nuclear hyperchromasia, multinucleation, and increased mitotic figures within the epidermis. What is the most likely diagnosis?
- A. Bowen's disease (Correct Answer)
- B. Bowenoid papulosis
- C. Erythroplasia of Queyrat
- D. Lichen sclerosus
- E. Condyloma acuminata
Premalignant skin lesions Explanation: ***Bowen's disease***
- The patient presents with **solitary, erythematous, crusty lesions on the penile shaft and finger**, which are characteristic of Bowen's disease, an in situ squamous cell carcinoma. The histological findings of **nuclear hyperchromasia, multinucleation, and increased mitotic figures within the epidermis** further confirm this diagnosis.
- The **lack of improvement with syphilis and eczema treatments** and the patient's **smoking history** (a risk factor for SCC) support this diagnosis over benign conditions.
*Bowenoid papulosis*
- This condition typically presents as **multiple, small, reddish-brown to violaceous papules**, often in the genital area of younger individuals.
- Unlike Bowen's disease, it is generally considered a **benign or low-grade intraepithelial neoplasia** with a lower risk of progression to invasive cancer.
*Erythroplasia of Queyrat*
- This is a form of **squamous cell carcinoma in situ** that specifically affects the **glans penis or prepuce**, presenting as a well-demarcated, velvety, erythematous patch.
- While histologically similar to Bowen's disease, the patient's lesion is on the **penile shaft and finger**, making Bowen's disease a more encompassing diagnosis for both sites.
*Lichen sclerosus*
- This is a **chronic inflammatory skin condition** characterized by **atrophic, white, sclerotic plaques**, often on the genitals.
- It does not present with the **crusting, oozing, and irregular borders** described, nor the specific histological features of squamous cell carcinoma in situ.
*Condyloma acuminata*
- These are **genital warts caused by HPV**, appearing as soft, flesh-colored, verrucous papules or plaques.
- They typically lack the **crusting, oozing, and histological features of severe atypia and increased mitotic figures** seen in this patient's biopsy.
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