Skin Tumors Practice Questions

Q: A 40-year-old man presents with multiple firm, pink nodules on his trunk. Histopathology reveals a storiform pattern with CD34 positivity. What is the most likely diagnosis?

Dermatofibrosarcoma protuberans. ***Dermatofibrosarcoma protuberans (DFSP)*** - DFSP is characterized by a distinctive **storiform (pinwheel) pattern** of spindle cells on histology. - **CD34 positivity** is a key immunohistochemical marker for DFSP, along with its presentation as a firm, pink nodule on the trunk. *Keloid* - Keloids are benign fibrous growths that result from an overgrowth of **scar tissue** and typically do not show a storiform pattern. - Histologically, keloids are characterized by thick, haphazardly arranged **collagen bundles** and are **CD34 negative**. *Neurofibroma* - Neurofibromas are benign peripheral nerve sheath tumors that exhibit a characteristic **"shredded carrot" collagen pattern** and spindle cells with wavy nuclei. - While they can be CD34 positive, the classic **storiform pattern** seen in this patient is not typical for neurofibroma. *Basal cell carcinoma* - Basal cell carcinoma typically presents with **peripheral palisading** of basaloid cells and stromal retraction, and does not exhibit a storiform pattern. - It is usually **CD34 negative** and often presents with ulceration or pearly borders, which are not described here.

Q: A 45-year-old man presents with multiple firm, yellowish nodules on his extensor surfaces. What is the most likely diagnosis?

Xanthomas. ***Xanthomas*** - **Xanthomas** are deposits of **cholesterol** and **lipids** in the skin, often appearing as firm, yellowish nodules. - They commonly occur on **extensor surfaces** such as elbows, knees, and Achilles tendons, and are associated with **hyperlipidemia**. *Lipomas* - **Lipomas** are benign tumors composed of **fat cells**, which are typically soft, movable, and painless. - While they can occur on extensor surfaces, they are generally **not yellowish** and do not indicate a systemic lipid disorder. *Seborrheic keratosis* - **Seborrheic keratoses** are common, benign skin growths that tend to be **waxy, 'stuck-on'** in appearance, and range in color from light tan to black. - They do not typically present as firm, yellowish nodules on extensor surfaces and are not associated with lipid abnormalities. *Erythema nodosum* - **Erythema nodosum** presents as tender, red, or violaceous nodules, primarily on the **shins**. - These lesions are painful and resolve with bruising-like discoloration, which is distinct from the firm, yellowish, non-tender nodules described.

Q: A 34-year-old man presents with a painless, hyperpigmented lesion on the inner aspect of his right thigh that has increased in size over the last 6 months. What is the most likely diagnosis?

Malignant melanoma. ***Malignant melanoma*** - A **painless**, **hyperpigmented lesion** that has **increased in size over 6 months** raises high suspicion for **malignant melanoma**, even in a non-sun-exposed area like the inner thigh. - The **progressive enlargement** over 6 months is the most concerning feature, suggesting malignancy. - Melanomas can occur anywhere on the body, including sites without sun exposure (acral, mucosal, and unexposed skin). - Key features supporting melanoma: **evolving size** (E of ABCDE criteria) and **hyperpigmentation** suggesting melanocytic origin. - **Definitive diagnosis requires biopsy** with histopathological examination. *Acanthosis nigricans* - Characterized by **dark, velvety, thickened patches** of skin, typically in body folds (neck, armpits, groin). - Usually **bilateral and symmetric**, not a solitary unilateral lesion. - Texture is velvety with papillomatous surface, different from the smooth surface implied here. - Not typically described as a progressively enlarging "lesion." *Basal cell carcinoma* - Most common skin cancer but typically presents as a **pearly or waxy nodule** with rolled borders and telangiectasias. - Predominantly occurs in **sun-exposed areas** (face, head, neck). - Pigmented BCC exists but is less common and usually shows characteristic rolled borders. - Inner thigh location is **atypical** for BCC. *Erythema nodosum* - Presents as **tender, painful, red nodules**, classically on the anterior shins. - An inflammatory condition, not a neoplastic process. - The lesion described is **painless** and **hyperpigmented**, which completely contradicts erythema nodosum. - Erythema nodosum lesions are acute/subacute, not slowly progressive over months.

Q: A 60-year-old male presents with a rough, scaly plaque on his forehead that has been slowly enlarging. What is the most likely diagnosis?

Actinic keratosis. ***Actinic keratosis*** - This presents as a **rough, scaly plaque** on sun-exposed areas like the forehead, which is characteristic of actinic keratosis. - Actinic keratoses are considered **premalignant lesions** with the potential to progress to squamous cell carcinoma. *Basal cell carcinoma* - Typically presents as a **pearly papule** with rolled borders and telangiectasias, or sometimes as an ulcerated lesion. - While it occurs on sun-exposed areas, the description of a **rough, scaly plaque** is less typical for classic basal cell carcinoma. *Melanoma* - Often presents with features associated with the **ABCDEs** (Asymmetry, Border irregularity, Color variability, Diameter >6mm, Evolving). - While it can be scaly, the primary concern for melanoma is its pigmentary changes and infiltrative growth, not just a rough plaque. *Seborrheic keratosis* - Characterized by a **"stuck-on" appearance**, often waxy or greasy, with well-demarcated borders and horn cysts (pseudohorn cysts). - While benign and common in older individuals, the description of a rough, scaly plaque is more indicative of a sun-damaged lesion rather than a seborrheic keratosis.

Q: Which of the following statements about Kaposi sarcoma is true?

Lesions are dark blue or purple. ***Lesions are dark blue or purple*** - **Kaposi sarcoma (KS)** lesions are characteristically **violaceous** or **dark blue/purple** due to blood vessel proliferation and extravasated red blood cells. - This distinct coloration is a key diagnostic feature, especially in later stages of the disease when the lesions have become more nodular or plaquelike. *The most common site is the scalp* - The most common sites for KS lesions are typically the **skin of the lower extremities**, followed by the face, trunk, and oral cavity. - While KS can occur on the scalp, it is not the most common primary site of presentation. *They are usually unifocal* - KS is often a **multifocal disease**, meaning lesions can appear in multiple locations simultaneously or sequentially. - The disease arises from the systemic spread of **HHV-8 infection**, rather than a single point of origin, leading to disseminated lesions. *Lymph nodes are never involved* - **Lymph node involvement** is common in KS, especially in the **AIDS-related** form and in regions with high endemic KS, like Africa. - Lymphadenopathy due to KS indicates more widespread disease and can affect prognosis.

Q: A 70-year-old male presents with a red, scaling plaque on the lower lip that has not healed over the past few months. What is the most likely diagnosis?

Squamous cell carcinoma. ***Squamous cell carcinoma*** - Presents as a **red, scaling plaque** on the lower lip, which is the **most common site for oral SCC** (90-95% of lip cancers) due to **chronic UV exposure**. - The history of **non-healing over several months** is highly suspicious for malignancy, particularly SCC in this location. - Lower lip SCC is common in elderly males with chronic sun exposure history. *Basal cell carcinoma* - Typically presents as a **pearly nodule with telangiectasias** or an ulcer, commonly found on sun-exposed skin but **rarely involves the lip**. - While BCC is the most common skin cancer overall, it is uncommon on the lips compared to SCC. *Actinic keratosis* - Characterized by **rough, scaling patches** on sun-exposed areas and is a **premalignant lesion** that can progress to SCC. - However, the description of a **non-healing lesion over months** points more strongly towards an already established malignancy (SCC) rather than a premalignant lesion. *Lichen planus* - An **inflammatory condition** that can affect the skin and mucous membranes, including the lips. - Oral lichen planus presents as **white lace-like patterns (Wickham's striae)** or erosions, not typically a persistent, red, scaling plaque that fails to heal.

Q: What is the most common type of skin cancer?

Basal cell carcinoma. ***Basal cell carcinoma*** - Basal cell carcinoma (BCC) is indeed the **most prevalent type of skin cancer**, accounting for approximately 80% of all non-melanoma skin cancers. - It arises from the **basal cells** of the epidermis and typically presents as a pearly nodule with rolled borders, often in sun-exposed areas. *Squamous cell carcinoma* - Squamous cell carcinoma (SCC) is the **second most common type** of skin cancer, making up about 20% of non-melanoma skin cancers. - It originates from the **squamous cells** in the outer layers of the epidermis and can appear as a red, scaly patch or an open sore. *Melanoma* - Melanoma is the **least common but most dangerous** type of skin cancer due to its high potential for metastasis. - It develops from **melanocytes**, the pigment-producing cells, and often presents as an irregular mole that changes in size, shape, or color. *Merkel cell carcinoma* - Merkel cell carcinoma is a **rare and aggressive neuroendocrine tumor** of the skin. - It commonly presents as a rapidly growing, firm, painless nodule, typically in sun-exposed areas of older individuals.

Q: A 65-year-old male presents with a new-onset lesion on the scalp that bleeds easily when touched. The lesion appears pearly with telangiectasias. Analyze the clinical features to determine the most likely diagnosis.

Basal cell carcinoma. ***Basal cell carcinoma*** - This is the most common type of skin cancer and classically presents as a **pearly (translucent) nodule** with **telangiectasias** (fine blood vessels) that may **bleed easily**. - It often appears on sun-exposed areas like the scalp and grows slowly, typically not metastasizing. *Squamous cell carcinoma* - Often presents as a **red, scaly patch, nodule, or ulcer** that may be tender and grow rapidly. - While it can bleed easily, it usually lacks the classic pearly appearance and prominent telangiectasias of BCC. *Actinic keratosis* - These are **pre-cancerous lesions** that appear as **rough, scaly, sandpaper-like patches** on sun-damaged skin. - While they can progress to squamous cell carcinoma, they are typically flat and do not present as pearly nodules that bleed easily. *Seborrheic keratosis* - These are **benign, waxy, "stuck-on" appearing lesions** that vary in color from light tan to dark brown or black. - They are usually non-bleeding and lack the pearly appearance and telangiectasias characteristic of BCC.

Q: A 70-year-old man presents with a skin ulcer that has not healed for several months. A biopsy reveals malignant cells forming keratin pearls. What is the most likely diagnosis?

Squamous cell carcinoma. ***Squamous cell carcinoma*** - The presence of **malignant cells forming keratin pearls** in the biopsy is a classic feature of squamous cell carcinoma [1]. - Ulceration and failure to heal over several months are significant indicators of this type of skin cancer . *Basal cell carcinoma* - Characterized by **peripheral palisading** of nuclei, not keratin pearls, differentiating it from squamous cell carcinoma [2]. - Typically presents as a **pearly nodular lesion** with a less aggressive behavior compared to squamous cell carcinoma [2]. *Melanoma* - Usually presents as an **irregularly shaped mole** with color variations, not associated with keratin pearls. - Biopsies typically show **pleomorphic cells** but do not exhibit the distinct keratinization seen in squamous cell carcinoma. *Merkel cell carcinoma* - A rare and aggressive skin cancer that is associated with **neuroendocrine features**, not keratin pearls. - Typically presents as a firm, painless **nodular lesion**, different from the ulcerative characteristics observed here. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 644-645. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1160-1162. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 643-644.

Question 1

A 40-year-old man presents with multiple firm, pink nodules on his trunk. Histopathology reveals a storiform pattern with CD34 positivity. What is the most likely diagnosis?

Accepted Answer

Dermatofibrosarcoma protuberans

Answer

Keloid

Answer

Neurofibroma

Answer

Basal cell carcinoma

Question 2

A 45-year-old man presents with multiple firm, yellowish nodules on his extensor surfaces. What is the most likely diagnosis?

Accepted Answer

Xanthomas

Answer

Lipomas

Answer

Seborrheic keratosis

Answer

Erythema nodosum

Question 3

A 34-year-old man presents with a painless, hyperpigmented lesion on the inner aspect of his right thigh that has increased in size over the last 6 months. What is the most likely diagnosis?

Accepted Answer

Malignant melanoma

Answer

Acanthosis nigricans

Answer

Basal cell carcinoma

Answer

Erythema nodosum

Question 4

A 60-year-old male presents with a rough, scaly plaque on his forehead that has been slowly enlarging. What is the most likely diagnosis?

Accepted Answer

Actinic keratosis

Answer

Basal cell carcinoma

Answer

Melanoma

Answer

Seborrheic keratosis

Question 5

Which of the following statements about Kaposi sarcoma is true?

Accepted Answer

Lesions are dark blue or purple

Answer

They are usually unifocal

Answer

The most common site is the scalp

Answer

Lymph nodes are never involved

Question 6

A 70-year-old male presents with a red, scaling plaque on the lower lip that has not healed over the past few months. What is the most likely diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Basal cell carcinoma

Answer

Actinic keratosis

Answer

Lichen planus

Question 7

What is the most common type of skin cancer?

Accepted Answer

Basal cell carcinoma

Answer

Squamous cell carcinoma

Answer

Melanoma

Answer

Merkel cell carcinoma

Question 8

A 65-year-old male presents with a new-onset lesion on the scalp that bleeds easily when touched. The lesion appears pearly with telangiectasias. Analyze the clinical features to determine the most likely diagnosis.

Accepted Answer

Basal cell carcinoma

Answer

Squamous cell carcinoma

Answer

Actinic keratosis

Answer

Seborrheic keratosis

Question 9

A 70-year-old man presents with a skin ulcer that has not healed for several months. A biopsy reveals malignant cells forming keratin pearls. What is the most likely diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Basal cell carcinoma

Answer

Melanoma

Answer

Merkel cell carcinoma

Question 10

A 38-year-old man presents with a solitary, firm, raised, reddish nodule on his back that has gradually increased in size over the past 8 months. Which condition is most likely?

Accepted Answer

Squamous cell carcinoma

Answer

Dermatofibroma

Answer

Mycosis fungoides

Answer

Basal cell carcinoma

Skin Tumors — MCQs

Skin Tumors — MCQs

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