Dermatopathology Practice Questions

Q: A 45-year-old man presents with a slowly enlarging nodule on his forearm. Histology reveals uniform spindle cells arranged in a storiform pattern with mild atypia and low mitotic activity. What is the most likely diagnosis?

Dermatofibrosarcoma protuberans. ***Dermatofibrosarcoma protuberans*** - This tumor is characterized by **uniform spindle cells arranged in a storiform (cartwheel) pattern** with infiltration into subcutaneous fat in a honeycomb pattern. - Shows **mild cytologic atypia and low to moderate mitotic activity**, making it a **low-grade locally aggressive sarcoma** originating in the dermis. - Typically presents as a **slowly enlarging, firm nodule or plaque** with high local recurrence rate but rare metastasis. - Characteristically shows **CD34 positivity** on immunohistochemistry. *Basal cell carcinoma* - An **epithelial tumor** showing **basaloid cells** with peripheral palisading, often with retraction artifact and stromal mucin [1]. - Presents as a **pearly nodule** with telangiectasias, not as spindle cell proliferation [1], [2]. - Slow-growing with very rare metastatic potential [1], [2]. *Squamous cell carcinoma* - An **epithelial malignancy** characterized by **keratinizing squamous cells** with intercellular bridges and keratin pearl formation [2]. - Does not show the characteristic **spindle cell storiform pattern** seen in DFSP. - May show invasion into deeper structures but has distinct epithelial morphology [2]. *Melanoma* - A **melanocytic malignancy** showing proliferation of atypical melanocytes, typically with melanin pigment (though amelanotic forms exist). - While spindle cell melanoma exists, it would show **melanocytic markers (S100, SOX10, Melan-A)** rather than CD34 positivity. - Lacks the characteristic storiform pattern and CD34 expression of DFSP. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1160-1162. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 643-644.

Q: A 50-year-old man presents with a non-healing ulcer on his lower leg. A biopsy reveals poorly differentiated squamous cells invading the dermis. What is the most likely diagnosis?

Squamous cell carcinoma. ***Squamous cell carcinoma*** - The presence of **poorly differentiated squamous cells** invading the dermis aligns with the histological features of squamous cell carcinoma [1]. - It often presents as a **non-healing ulcer**, particularly on sun-exposed areas, which is consistent with the patient's symptoms [2,3]. *Actinic keratosis* - Typically presents as **rough, scaly patches**, not as a deep ulcer invading dermal layers. - Although it is a precursor to squamous cell carcinoma, it lacks the **poor differentiation** seen here [1]. *Basal cell carcinoma* - Characterized by **peripheral palisading** and is usually **not invasive** like squamous cell carcinoma [3]. - It presents more commonly as a **pearly nodule** or ulcerated lesion rather than poorly differentiated squamous cells [2]. *Melanoma* - Melanoma primarily arises from **melanocytes** and presents as a change in an existing mole or a new dark lesion, rather than **squamous cells**. - Histological features include **atypical melanocytes**, which are not present in this biopsy report. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 644-645. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 631-633. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 643-644.

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.

Q: A 50-year-old woman presents with a painful, ulcerated lesion on the lower lip. A biopsy shows dysplastic squamous cells invading the basement membrane. What is the most likely diagnosis?

Squamous cell carcinoma. ***Squamous cell carcinoma*** - The presence of **dysplastic squamous cells** invading the **basement membrane** indicates a malignant process, consistent with squamous cell carcinoma [1][2]. - This lesion is typically **painful and ulcerative**, further supporting the diagnosis in this clinical scenario [1]. *Actinic keratosis* - Actinic keratosis presents as a **rough, scaly patch** and does not usually involve **invasion of the basement membrane** [1]. - It is a precursor lesion but not a full-thickness carcinoma, hence would not show dysplasia at the invasive level. *Malignant melanoma* - Malignant melanoma typically arises from **melanocytes**, presenting differently than squamous lesions, often with **pigmented lesions**. - The biopsy findings of **dysplastic squamous cells** are not characteristic of melanoma, which shows atypical **melanocytes** instead. *Basal cell carcinoma* - Basal cell carcinoma usually presents as a **pearly, nodular lesion** and does not show **dysplastic squamous cells** as its primary cell type. - It tends to be **non-invasive** and does not typically invade the basement membrane in the manner described in this case. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 644-645. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 643-644.

Q: Increase in the thickness of the prickle cell layer of the epidermis is called?

Acanthosis. ***Acanthosis*** - **Acanthosis** refers to the diffuse epidermal hyperplasia, specifically the increase in the thickness of the **stratum spinosum** (prickle cell layer) [1]. - This histological finding is common in various dermatological conditions, including **psoriasis** [1] and **acanthosis nigricans** [2]. *Hypergranulosis (thickening of the stratum granulosum)* - **Hypergranulosis** specifically describes the thickening of the **stratum granulosum**, the granular layer of the epidermis. - While it represents epidermal thickening, it is distinct from acanthosis which involves the prickle cell layer. *Hyperkeratosis (thickening of the stratum corneum)* - **Hyperkeratosis** is the thickening of the outermost layer of the epidermis, the **stratum corneum**, which is composed of dead keratinocytes [3]. - This condition is often seen in chronic rubbing or pressure, leading to the formation of **calluses** or **corns**. *Spongiosis (fluid accumulation in the epidermis)* - **Spongiosis** is characterized by intercellular **edema** (fluid accumulation) within the epidermis, particularly in the stratum spinosum. - This leads to widening of the spaces between keratinocytes with stretched intercellular bridges, commonly seen in **acute eczematous dermatitis**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 640-641. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1153-1154. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1156.

Q: Which type of skin cancer is characterized by keratinization and pearl formation?

Squamous cell carcinoma (SCC). ***Squamous cell carcinoma*** - Characterized by **keratinization** and the formation of **keratin pearls** which are indicative of its differentiation [1]. - This type of cancer arises from the **keratinocytes** in the epidermis, often associated with **sun exposure** and **chronic irritation**. *Lymphoma* - Primarily affects the **lymphatic system** and is characterized by **lymphadenopathy** and systemic symptoms rather than keratinization. - Does not involve **epithelial cells** or the formation of keratin pearls. *Basal cell carcinoma* - Typically presents with **peripheral palisading** of nuclei and does not show significant keratinization. - Rarely forms keratin pearls as it arises from **basal cells** and involves different growth patterns. *Melanoma* - Mainly arises from **melanocytes** and is associated with **pigmented lesions**, not keratinization. - Melanoma can cause **ulceration** but does not typically feature keratin pearls or significant keratinization. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 644-645.

Q: Which layer of the epidermis is primarily involved in spongiosis?

Stratum spinosum. ***Stratum spinosum*** - **Spongiosis** is characterized by **intercellular edema** (fluid accumulation between cells) within the epidermis [1], primarily affecting the **stratum spinosum** [2]. - The cells of the stratum spinosum, known as **keratinocytes**, become separated by this edema, giving the tissue a "spongy" appearance on histology due to the preservation of **desmosomal attachments**. *Stratum basale* - The **stratum basale** is the deepest layer of the epidermis, responsible for **cell proliferation** and attachment to the basement membrane. - While edema can affect all epidermal layers in severe cases, spongiosis specifically refers to the intercellular edema most prominent in the stratum spinosum [2]. *Stratum corneum* - The **stratum corneum** is the outermost layer of the epidermis, composed of dead, flattened **keratinocytes** that provide a protective barrier. - Edema in this layer is less common and would not be described as spongiosis, which implies living cells with preserved intercellular junctions. *Stratum granulosum* - The **stratum granulosum** lies above the stratum spinosum and is characterized by cells containing **keratohyalin granules**. - While it can be affected by intercellular edema, the most pronounced and characteristic spongiosis occurs in the stratum spinosum where cells are still actively synthesizing keratin and have strong desmosomal connections [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, p. 636. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1166.

Q: Which gene mutation is commonly associated with malignant melanoma?

CDKN2A. ***CDK2A*** - CDK2A mutations are implicated in malignant melanoma as they disrupt the **cell cycle regulation**, contributing to uncontrolled cell growth [1]. - Loss of CDK2A function leads to reduced **p16INK4A**, a crucial inhibitor of cyclin-dependent kinases involved in **G1/S phase transition** [1,3]. - Germline mutations of p16 (CDKN2A) are present in 25% of melanoma-prone kindreds [2], and germline mutations in CDKN2A are associated with familial forms of melanoma [3]. *RET* - RET mutations are primarily associated with **medullary thyroid carcinoma** and **multiple endocrine neoplasia type 2**, not melanoma. - It is involved in the signaling pathways but does not have a direct link to melanoma pathogenesis. *None* - Suggesting "none" misrepresents the reality that specific mutations do occur in malignant melanoma, including **CDK2A** and **BRAF**. - This option fails to recognize the importance of genetic alterations in cancer development and progression. *N-myc* - N-myc mutations are primarily associated with **neuroblastoma** and not typically linked to malignant melanoma. - In melanoma, mutations of this gene do not play a significant role in its pathophysiology compared to another tumor suppressor gene like **CDK2A**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 297-298. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 305-306.

Q: Which of the following conditions does NOT exhibit dyskeratosis?

Lichen planus. ***Lichen planus*** - This is an **inflammatory skin condition** characterized by **puritic, polygonal, planar, purple papules and plaques** [1]. - Histologically, it shows a **sawtooth pattern of rete ridges**, basal cell liquefaction degeneration, and a band-like lymphocytic infiltrate, but **no dyskeratosis**. *Squamous cell carcinoma* - This is a **malignant tumor** of keratinocytes that frequently exhibits **dyskeratosis** (premature keratinization of individual cells) [2]. - Dyskeratosis is a key feature indicating abnormal keratinocyte maturation and cellular atypia. *Bowen's disease* - Also known as **squamous cell carcinoma in situ**, Bowen's disease is a full-thickness atypia of the epidermis [2]. - It frequently demonstrates **dyskeratosis** among other features of keratinocyte atypia, such as nuclear pleomorphism and mitotic figures. *Darier's disease* - This is an **autosomal dominant genodermatosis** characterized by abnormal keratinization. - Histologically, it classically presents with **dyskeratosis** in the form of corps ronds and grains, along with suprabasal acantholysis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1168-1170. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 644-645.

Q: A 77-year-old man has a lesion on the right side of his face that has enlarged slowly over the past 5 years. On examination, the 3-cm lesion has irregular borders, irregular brown to black pigmentation, and a central 2-mm raised blue-black nodule. The lesion is resected and microscopically shows radial growth of large round malignant cells, some isolated and others in nests in the epidermis and superficial papillary dermis. The cells have prominent red nucleoli and dust-like cytoplasmic pigment. Which mutated gene is most likely to be present in the skin lesion of this man?

BRAF. ***BRAF*** - The presence of **irregular pigmentation** and characteristics of melanoma suggest an association with mutations, particularly in the **BRAF gene**, often seen in **cutaneous melanoma** [1,2]. - BRAF mutations are commonly involved in **cell proliferation** and survival pathways that contribute to the malignant behavior of melanoma cells [1]. *TYR* - TYR (tyrosinase) is primarily involved in **melanin synthesis** and is not directly implicated in melanoma pathogenesis. - Although mutations may affect pigmentation, they do not correlate with increased tumorigenicity seen in melanoma. *ATM* - ATM (Ataxia Telangiectasia Mutated) is related to **DNA repair mechanisms** and is more associated with predisposition to **other cancers** rather than directly involved with melanoma. - It does not account for the specific features of **BRAF mutation** in melanoma progression. *NF1* - NF1 (Neurofibromatosis type 1) mutations are associated with neurofibromas and possibly with a predisposition to certain types of **malignancies**, but not primarily to **melanomas**. - The clinical presentation does not support an NF1 mutation considering the distinct features of the lesion described. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1152-1153.

Question 1

A 45-year-old man presents with a slowly enlarging nodule on his forearm. Histology reveals uniform spindle cells arranged in a storiform pattern with mild atypia and low mitotic activity. What is the most likely diagnosis?

Accepted Answer

Dermatofibrosarcoma protuberans

Answer

Basal cell carcinoma

Answer

Squamous cell carcinoma

Answer

Melanoma

Question 2

A 50-year-old man presents with a non-healing ulcer on his lower leg. A biopsy reveals poorly differentiated squamous cells invading the dermis. What is the most likely diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Basal cell carcinoma

Answer

Melanoma

Answer

Actinic keratosis

Question 3

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 4

A 50-year-old woman presents with a painful, ulcerated lesion on the lower lip. A biopsy shows dysplastic squamous cells invading the basement membrane. What is the most likely diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Basal cell carcinoma

Answer

Malignant melanoma

Answer

Actinic keratosis

Question 5

Increase in the thickness of the prickle cell layer of the epidermis is called?

Accepted Answer

Acanthosis

Answer

Hypergranulosis (thickening of the stratum granulosum)

Answer

Hyperkeratosis (thickening of the stratum corneum)

Answer

Spongiosis (fluid accumulation in the epidermis)

Question 6

Which type of skin cancer is characterized by keratinization and pearl formation?

Accepted Answer

Squamous cell carcinoma (SCC)

Answer

Melanoma

Answer

Basal cell carcinoma (BCC)

Answer

Lymphoma

Question 7

Which layer of the epidermis is primarily involved in spongiosis?

Accepted Answer

Stratum spinosum

Answer

Stratum basale

Answer

Stratum corneum

Answer

Stratum granulosum

Question 8

Which gene mutation is commonly associated with malignant melanoma?

Accepted Answer

CDKN2A

Answer

MYCN

Answer

RET

Answer

BRAF

Question 9

Which of the following conditions does NOT exhibit dyskeratosis?

Accepted Answer

Lichen planus

Answer

Bowen's disease

Answer

Squamous cell carcinoma

Answer

Darier's disease

Question 10

A 77-year-old man has a lesion on the right side of his face that has enlarged slowly over the past 5 years. On examination, the 3-cm lesion has irregular borders, irregular brown to black pigmentation, and a central 2-mm raised blue-black nodule. The lesion is resected and microscopically shows radial growth of large round malignant cells, some isolated and others in nests in the epidermis and superficial papillary dermis. The cells have prominent red nucleoli and dust-like cytoplasmic pigment. Which mutated gene is most likely to be present in the skin lesion of this man?

Accepted Answer

BRAF

Answer

ATM

Answer

NF1

Answer

TYR

Dermatopathology — MCQs

Dermatopathology — MCQs

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