Dermatopathology Practice Questions

Q: A 58-year-old man with a 40-pack-year smoking history presents with progressive dyspnea and a dry cough. Chest CT reveals bilateral pleural thickening and a right pleural mass. Thoracoscopic biopsy is performed. The photomicrograph shows a biphasic tumor with epithelioid cells forming tubulopapillary structures intermixed with a spindle-cell sarcomatoid component. Elongated, golden-brown, beaded structures with a translucent core are identified within the adjacent lung parenchyma, each coated with iron-protein complexes. Which of the following structures are most specifically represented by the coated inclusions seen in this specimen?

Ferruginous bodies formed around inhaled mineral fibers. ***Ferruginous bodies formed around inhaled mineral fibers*** - These are **golden-brown, beaded, dumbbell-shaped** structures consisting of an **asbestos fiber** core coated with **iron-protein complexes** (hemosiderin). - Their presence in lung parenchyma indicates significant **asbestos exposure**, which is the primary risk factor for the **malignant mesothelioma** (biphasic tumor) described. *Psammoma bodies representing dystrophic calcification within papillary fronds* - These are **concentric laminated calcifications** typically seen in papillary thyroid carcinoma, meningioma, and serous ovarian tumors. - While they can be found in some mesotheliomas, they do not have a **beaded, golden-brown** appearance or a fiber core. *Schaumann bodies found within giant cells of granulomatous inflammation* - These are **laminated calcium and protein** inclusions found inside **multinucleated giant cells** in granulomatous diseases like **sarcoidosis**. - They lack the characteristic **translucent mineral core** and dumbbell shape of ferruginous bodies. *Corpora amylacea resulting from polyglucosan accumulation in alveolar macrophages* - These are small **hyaline masses** found in the prostate and the alveoli of older patients, representing **degenerate cells** or thickened secretions. - They are not associated with **asbestos exposure** or iron coating and do not present as beaded fibers. *Charcot-Leyden crystals derived from eosinophil membrane phospholipase* - These are **hexagonal, needle-like crystals** formed from the breakdown of **eosinophils**. - They are characteristic of **asthma** or other eosinophilic inflammatory processes, not asbestos-related pleural malignancies.

Q: A 35-year-old man presents with targetoid lesions on his palms and oral mucosa following treatment for Mycoplasma pneumonia. Skin biopsy shows necrotic keratinocytes throughout all layers of the epidermis with minimal inflammatory infiltrate. Direct immunofluorescence is negative. The patient develops similar lesions with each infection. Analyze the pathophysiology to identify the primary mechanism.

CD8+ T-cell mediated cytotoxicity against keratinocytes. ***CD8+ T-cell mediated cytotoxicity against keratinocytes*** - The patient presents with **Erythema Multiforme (EM)**, which is a **Type IV hypersensitivity reaction** characterized by CD8+ T-cell attack on keratinocytes expressing foreign antigens. - **Mycoplasma pneumoniae** is a common trigger; the pathology involves **epidermal cell death** (necrotic keratinocytes) through the release of perforins and granzymes by activated T-cells. *Type II hypersensitivity with antibody-mediated cytotoxicity* - This mechanism involves **IgG or IgM** antibodies binding to cell surface antigens, which is typical of diseases like **pemphigus vulgaris**. - The **negative direct immunofluorescence (DIF)** in this case specifically rules out antibody-mediated damage to keratinocytes or the basement membrane. *Type III hypersensitivity with immune complex deposition* - This mechanism involves the deposition of **antigen-antibody complexes** in tissues, classically seen in **systemic lupus erythematosus** or vasculitis. - EM lacks the characteristic **leukocytoclastic vasculitis** and deposition of complexes in vessel walls that define Type III reactions. *Type I hypersensitivity with IgE-mediated mast cell degranulation* - Type I reactions cause **urticaria (hives)** or anaphylaxis, presenting as transient, itchy wheals rather than persistent **targetoid lesions** with necrosis. - Histology would show **dermal edema** and eosinophils rather than the **full-thickness epidermal necrosis** seen in this patient. *Complement-mediated direct cellular injury* - While complement can be secondary to other processes, primary complement injury lacks the specific **T-cell driven** memory response seen in recurrent EM. - The absence of immune deposits on **DIF** confirms that the classical complement pathway is not the primary initiator of the keratinocyte death.

Q: A 40-year-old woman with systemic lupus erythematosus presents with photosensitive facial erythema. Skin biopsy shows vacuolar interface dermatitis with thickened basement membrane, dermal mucin deposition, and perivascular lymphocytic infiltrate. Direct immunofluorescence shows granular deposits of IgG, IgM, and C3 at the dermal-epidermal junction. Analyze these findings to determine which additional laboratory test would best correlate with disease activity.

Anti-double stranded DNA antibodies. ***Anti-double stranded DNA antibodies*** - **Anti-dsDNA antibodies** are highly specific for **SLE** and provide the strongest correlation with **disease activity** and flares, particularly **lupus nephritis**. - A rise in **anti-dsDNA titers** often reflects active systemic involvement and can be used to monitor response to treatment. *Anti-Ro/SSA antibodies* - These are frequently associated with **subacute cutaneous lupus** and **neonatal lupus**, but they do not reliably correlate with overall disease activity. - While present in many SLE patients, they are not used as longitudinal markers for tracking **autoimmune flares**. *Antinuclear antibody titer* - **ANA** is a highly sensitive screening tool for SLE, but it lacks **specificity** and does not change based on clinical severity. - Monitoring **ANA titers** over time is not useful for assessing response to therapy or identifying an active disease state. *Anti-Smith antibodies* - **Anti-Smith (Sm)** antibodies are highly specific for the diagnosis of SLE, but their levels remain stable regardless of disease status. - Unlike **anti-dsDNA**, they are not considered dynamic markers of **disease activity** or renal involvement. *Complement C3 and C4 levels* - Decreased levels of **C3 and C4** indicate complement consumption and are used to monitor flares, but they are generally secondary markers compared to **anti-dsDNA**. - While useful for tracking **lupus nephritis**, complement levels are less specific for SLE activity than direct **antibody titers**.

Q: A 62-year-old woman presents with a pigmented lesion on her back. Biopsy shows atypical melanocytes arranged in nests at the dermal-epidermal junction and scattered as single cells through the epidermis with pagetoid spread. The melanocytes extend into the papillary dermis to a depth of 1.8 mm. No ulceration is present, and the mitotic rate is 3/mm². Analyze this pathology to determine the appropriate staging workup.

Sentinel lymph node biopsy and consideration of CT imaging. ***Sentinel lymph node biopsy and consideration of CT imaging*** - For malignant melanoma with a **Breslow depth** of **1.8 mm (T2a)**, a **sentinel lymph node biopsy (SLNB)** is the standard of care for staging the regional nodal basin. - In clinical stage II (T2-T4), **baseline imaging** (like CT) may be considered to rule out distant metastasis, especially when high-risk features like a high **mitotic rate** (3/mm²) are present. *No additional workup required* - This is incorrect because any melanoma with a depth **>0.8 mm** requires at least an **SLNB** to assess for occult nodal involvement. - Failure to stage this lesion would lead to under-diagnosis of potential **Stage III disease**. *Sentinel lymph node biopsy only* - While SLNB is essential, it ignores current guidelines that allow for the clinical **consideration of cross-sectional imaging** in intermediate-thickness melanomas with worrisome features. - Staging for a 1.8 mm lesion often involves a more systemic evaluation than just the **sentinel node**. *CT chest, abdomen, and pelvis* - Performing systemic imaging alone without a **sentinel lymph node biopsy** is inappropriate, as nodal status is the most important **prognostic factor**. - Routine CT imaging is generally reserved for patients with **positive nodes** or those with thicker (T3/T4) primary tumors. *PET-CT scan* - **PET-CT** has low sensitivity for detecting small-volume metastatic disease in early-stage (Stage I/II) melanoma and is not recommended as a primary staging tool. - Current guidelines favor **SLNB** and potentially **CT/MRI** over PET-CT for Initial staging of localized intermediate-thickness melanoma.

Q: A 3-year-old boy presents with tense bullae on his trunk and extremities following a viral upper respiratory infection. Direct immunofluorescence shows linear IgA deposits along the basement membrane zone. Indirect immunofluorescence is negative. Apply this immunopathological pattern to select the most appropriate initial treatment.

Dapsone therapy. ***Dapsone therapy*** - The clinical presentation and **linear IgA deposits** along the basement membrane zone confirm a diagnosis of **Linear IgA Bullous Dermatosis (LABD)**, also known as **chronic bullous disease of childhood**. - **Dapsone** is the first-line treatment of choice as it effectively inhibits **neutrophil recruitment** and activation, which are primary drivers of this IgA-mediated condition. *High-dose intravenous immunoglobulin* - While used for severe or refractory cases of autoimmune blistering diseases, it is not the **initial treatment** for LABD. - It is generally reserved for patients who do not respond to or cannot tolerate more standard therapies like **sulfones**. *Oral corticosteroids and azathioprine* - This combination is standard for **Pemphigus Vulgaris** but is considered second-line or adjunctive for LABD if dapsone is insufficient. - **Azathioprine** takes weeks to become effective and is not the most appropriate immediate monotherapy for this specific immunopathological pattern. *Plasmapheresis* - This procedure removes circulating antibodies and is typically used in **life-threatening** or severe cases of **Pemphigus** or **Bullous Pemphigoid**. - Since **indirect immunofluorescence** is negative in this patient, signifying a lack of significant circulating antibodies, plasmapheresis would be less effective. *Rituximab infusion* - This anti-CD20 monoclonal antibody is often used for **recalcitrant Pemphigus** by depleting B-cells. - It is not a first-line therapy for children with LABD, which often has a **benign course** and responds rapidly to less aggressive interventions.

Question 1

A 34-year-old woman presents with fatigue, night sweats, and a painless cervical lymph node mass for 3 months. Excisional biopsy of the lymph node is performed. The photomicrograph demonstrates a mixed cellular infiltrate with scattered large binucleated cells possessing prominent eosinophilic 'owl-eye' nucleoli, set against a background of lymphocytes, plasma cells, eosinophils, and fibroblasts. Immunohistochemical staining of the large cells is positive for CD15 and CD30 and negative for CD45. Which of the following best describes the cell of origin of the large binucleated cells seen in this lesion?

Accepted Answer

Transformed follicular center B cells arrested in late germinal center or post-germinal center stage

Answer

Peripheral T cells undergoing clonal expansion in response to viral antigen

Answer

Immature myeloid precursors that have undergone aberrant class-switch recombination

Answer

Marginal zone B cells that have acquired EBV-driven oncogenic transformation

Answer

Plasmacytoid dendritic cell precursors activated by interferon-gamma signaling

Question 2

A 67-year-old man with a 20-year history of poorly controlled type 2 diabetes mellitus dies of a myocardial infarction. At autopsy, the kidneys are symmetrically enlarged with a granular cortical surface. PAS staining of the renal cortex shows PAS-positive ovoid deposits within the mesangium of glomeruli, compressing the adjacent capillary loops. Which of the following best describes the composition and pathogenetic mechanism of these deposits?

Accepted Answer

Glycosylated type IV collagen and laminin accumulating due to non-enzymatic glycation and increased mesangial matrix production

Answer

Amyloid fibrils derived from serum amyloid A protein deposited via chronic inflammatory activation of mesangial cells

Answer

Immune complex deposits of IgA and complement C3 accumulating in the mesangium following mucosal antigenic stimulation

Answer

Fibrin thrombi within mesangial capillaries resulting from thrombotic microangiopathy driven by endothelial injury

Answer

Lipid-laden foam cells infiltrating the mesangium secondary to dyslipidemia-driven glomerular macrophage accumulation

Question 3

A 58-year-old man with a 40-pack-year smoking history presents with progressive dyspnea and a dry cough. Chest CT reveals bilateral pleural thickening and a right pleural mass. Thoracoscopic biopsy is performed. The photomicrograph shows a biphasic tumor with epithelioid cells forming tubulopapillary structures intermixed with a spindle-cell sarcomatoid component. Elongated, golden-brown, beaded structures with a translucent core are identified within the adjacent lung parenchyma, each coated with iron-protein complexes. Which of the following structures are most specifically represented by the coated inclusions seen in this specimen?

Accepted Answer

Ferruginous bodies formed around inhaled mineral fibers

Answer

Psammoma bodies representing dystrophic calcification within papillary fronds

Answer

Schaumann bodies found within giant cells of granulomatous inflammation

Answer

Corpora amylacea resulting from polyglucosan accumulation in alveolar macrophages

Answer

Charcot-Leyden crystals derived from eosinophil membrane phospholipase

Question 4

A 50-year-old woman with rheumatoid arthritis on methotrexate develops rapidly progressive painful ulcers on her legs with violaceous undermined borders. Biopsy shows neutrophilic dermal infiltrate with areas of necrosis, but no vasculitis or infection. Wound cultures are negative. Despite debridement, the ulcers worsen. C-ANCA and P-ANCA are negative. Evaluate the diagnosis and determine the management that addresses both the cutaneous condition and systemic disease.

Accepted Answer

Continue methotrexate, add TNF-alpha inhibitor and systemic corticosteroids

Answer

Discontinue all immunosuppression to allow wound healing

Answer

Increase methotrexate dose and add wound care

Answer

Discontinue methotrexate, start cyclosporine and prednisone

Answer

Start broad-spectrum antibiotics and surgical debridement

Question 5

A 25-year-old woman presents with painful oral ulcers and a pustular rash at venipuncture sites. She has genital ulcers and a history of recurrent uveitis. Skin biopsy from a pustule shows neutrophilic infiltrate in the dermis without vasculitis or infection. HLA-B51 testing is positive. She is planning pregnancy. Evaluate the management strategy considering disease control and pregnancy planning.

Accepted Answer

Start infliximab, use contraception, then transition to low-risk therapy before conception

Answer

Start methotrexate for disease control

Answer

Start colchicine monotherapy and proceed with pregnancy

Answer

Start high-dose corticosteroids and azathioprine, delay pregnancy

Answer

Avoid all immunosuppression and manage symptoms only

Question 6

A 70-year-old man on chronic warfarin therapy presents with sudden onset of painful purpura on his thighs and buttocks three days after starting warfarin for atrial fibrillation. He has a history of multiple DVTs. Skin biopsy shows thrombosis of dermal blood vessels with minimal inflammation. Laboratory studies show an INR of 3.5. Evaluate the pathophysiology and determine the most appropriate immediate management.

Accepted Answer

Discontinue warfarin, give protein C concentrate and alternative anticoagulation

Answer

Reduce warfarin dose and add compression therapy

Answer

Discontinue all anticoagulation and monitor

Answer

Continue warfarin and add aspirin for antiplatelet effect

Answer

Discontinue warfarin, give vitamin K and fresh frozen plasma, start heparin bridge

Question 7

A 35-year-old man presents with targetoid lesions on his palms and oral mucosa following treatment for Mycoplasma pneumonia. Skin biopsy shows necrotic keratinocytes throughout all layers of the epidermis with minimal inflammatory infiltrate. Direct immunofluorescence is negative. The patient develops similar lesions with each infection. Analyze the pathophysiology to identify the primary mechanism.

Accepted Answer

CD8+ T-cell mediated cytotoxicity against keratinocytes

Answer

Type II hypersensitivity with antibody-mediated cytotoxicity

Answer

Type III hypersensitivity with immune complex deposition

Answer

Type I hypersensitivity with IgE-mediated mast cell degranulation

Answer

Complement-mediated direct cellular injury

Question 8

A 40-year-old woman with systemic lupus erythematosus presents with photosensitive facial erythema. Skin biopsy shows vacuolar interface dermatitis with thickened basement membrane, dermal mucin deposition, and perivascular lymphocytic infiltrate. Direct immunofluorescence shows granular deposits of IgG, IgM, and C3 at the dermal-epidermal junction. Analyze these findings to determine which additional laboratory test would best correlate with disease activity.

Accepted Answer

Anti-double stranded DNA antibodies

Answer

Anti-Ro/SSA antibodies

Answer

Antinuclear antibody titer

Answer

Anti-Smith antibodies

Answer

Complement C3 and C4 levels

Question 9

A 62-year-old woman presents with a pigmented lesion on her back. Biopsy shows atypical melanocytes arranged in nests at the dermal-epidermal junction and scattered as single cells through the epidermis with pagetoid spread. The melanocytes extend into the papillary dermis to a depth of 1.8 mm. No ulceration is present, and the mitotic rate is 3/mm². Analyze this pathology to determine the appropriate staging workup.

Accepted Answer

Sentinel lymph node biopsy and consideration of CT imaging

Answer

No additional workup required

Answer

Sentinel lymph node biopsy only

Answer

CT chest, abdomen, and pelvis

Answer

PET-CT scan

Question 10

A 3-year-old boy presents with tense bullae on his trunk and extremities following a viral upper respiratory infection. Direct immunofluorescence shows linear IgA deposits along the basement membrane zone. Indirect immunofluorescence is negative. Apply this immunopathological pattern to select the most appropriate initial treatment.

Accepted Answer

Dapsone therapy

Answer

High-dose intravenous immunoglobulin

Answer

Oral corticosteroids and azathioprine

Answer

Plasmapheresis

Answer

Rituximab infusion

Dermatopathology — MCQs

Dermatopathology — MCQs

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