I85PREP
⌘ K
ABPath Anatomic Pathology study materials
ABPath Anatomic Pathology study resources

ABPath Anatomic Pathology practice questions

One question at a time. Build your ABPath Anatomic Pathology understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Surgical Pathology

A 58-year-old woman has an ill-defined breast mass. Microscopy shows small, uniform cells infiltrating in single file through fibrous stroma with no gland formation. Which immunohistochemical result best supports this diagnosis?

  1. Strong membranous E-cadherin in tumor cells
  2. Nuclear estrogen receptor positivity
  3. Loss of membranous E-cadherin Correct answer.
  4. Cytokeratin 5/6 positivity

Explanation

Invasive lobular carcinoma is defined by discohesive cells that infiltrate in single file, reflecting loss of E-cadherin from biallelic CDH1 inactivation. Membranous E-cadherin is retained in ductal lesions, so demonstrating its absence supports lobular differentiation. Estrogen receptor status and cytokeratin 5/6 results do not separate the two subtypes.

Question 2Surgical Pathology

Which nuclear feature is most characteristic of papillary thyroid carcinoma on fine-needle aspiration?

  1. Nuclei with grooves and intranuclear pseudoinclusions Correct answer.
  2. Nuclei with salt-and-pepper chromatin and prominent nucleoli
  3. Powdery chromatin with prominent macronucleoli
  4. Uniform nuclei with stippled chromatin and absent nucleoli

Explanation

Papillary thyroid carcinoma nuclei are enlarged and optically clear with irregular contours, grooves, and intranuclear cytoplasmic pseudoinclusions. These changes are the basis for cytologic diagnosis even when papillary architecture is not sampled. Salt-and-pepper chromatin with prominent nucleoli indicates a neuroendocrine lesion instead.

Question 3Surgical Pathology

In prostatic adenocarcinoma, which architecture corresponds to Gleason pattern 4?

  1. Solid sheets of cells with no lumen
  2. Glands with central comedonecrosis
  3. Well-formed, discrete, round glands
  4. Fused glands and cribriform structures Correct answer.

Explanation

Gleason pattern 4 encompasses fused glands, cribriform glands, and poorly formed glands, all of which lack the discrete rounded contour of pattern 3. Pattern 5 is assigned when there is comedonecrosis, solid sheets, or single-cell infiltration. Recognizing cribriform architecture as pattern 4 is important because it upgrades the Gleason score.

Question 4Surgical Pathology

A lung biopsy shows a non-small cell carcinoma. Which immunophenotype best supports adenocarcinoma rather than squamous cell carcinoma?

  1. CK20 and CDX2 positive, TTF-1 negative
  2. p63 positive, napsin A negative, CK7 negative
  3. p40 and CK5/6 positive, TTF-1 and napsin A negative
  4. TTF-1 and napsin A positive, p40 negative Correct answer.

Explanation

Lung adenocarcinoma typically expresses TTF-1 and napsin A, whereas squamous cell carcinoma expresses p40 and CK5/6. A panel pairing a positive adenocarcinoma marker with a negative squamous marker resolves most non-small cell carcinomas on small biopsies. CDX2 and CK20 positivity would instead point toward a colorectal primary.

Question 5Surgical Pathology

Which histologic pattern is characteristic of diffuse-type gastric adenocarcinoma in the Lauren classification?

  1. Well-formed glandular structures with intestinal metaplasia
  2. Discohesive signet ring cells with abundant mucin Correct answer.
  3. Solid nests with squamous differentiation
  4. Papillary fronds lined by stratified columnar cells

Explanation

Diffuse-type gastric adenocarcinoma shows discohesive cells with intracytoplasmic mucin that infiltrate the wall without forming glands, often as signet ring cells. The intestinal type instead forms glands and arises through intestinal metaplasia and dysplasia. The distinction matters because diffuse-type tumors carry a worse prognosis and different molecular drivers.

Question 6Surgical Pathology

Breslow thickness of a primary cutaneous melanoma is measured from which point?

  1. The base of the stratum corneum to the deepest tumor cell
  2. The granular layer of the epidermis to the deepest invasive tumor cell Correct answer.
  3. The top of the granular layer to the deepest dermal nest plus one millimeter
  4. The dermoepidermal junction to the deepest tumor cell

Explanation

Breslow thickness is measured from the granular layer of the overlying epidermis, or the base of an ulcer, to the deepest invasive tumor cell. It must be measured perpendicular to the skin surface and reported in millimeters to one decimal place. Other reference points give values that do not correlate with outcome.

Question 7Surgical Pathology

Which immunohistochemical marker is most sensitive and specific for hepatocellular carcinoma?

  1. CDX2
  2. CK7
  3. CA19-9
  4. Arginase-1 Correct answer.

Explanation

Arginase-1 is a highly sensitive and specific marker of hepatocellular differentiation and is positive in most hepatocellular carcinomas. Its specificity exceeds that of HepPar-1, which can be expressed in other adenocarcinomas. The other listed markers label biliary, intestinal, and pancreaticobiliary lineages.

Question 8Surgical Pathology

Which feature best distinguishes a sessile serrated lesion from a hyperplastic polyp in the colon?

  1. Thickened basement membrane under the surface epithelium
  2. Increase in goblet cells with mucin depletion
  3. Serration confined to the upper crypt compartment
  4. Basal crypt dilation with boot-shaped glands Correct answer.

Explanation

Sessile serrated lesions show crypt dilation and horizontal, boot-shaped growth along the muscularis mucosae with serration extending to the crypt base. Hyperplastic polyps have serration confined to the upper crypt and lack basal architectural distortion. This distinction matters because sessile serrated lesions belong to the serrated pathway with BRAF mutation and CpG island methylation.

Question 9Surgical Pathology

Which histologic feature favors a phyllodes tumor over a fibroadenoma?

  1. Leaf-like architecture with hypercellular stroma Correct answer.
  2. Well-circumscribed lobules of compressed ducts
  3. Uniform stromal cells with hyalinized collagen bands
  4. Apocrine metaplasia within dilated ducts

Explanation

Phyllodes tumors show an intracanalicular leaf-like architecture with hypercellular stroma, stromal overgrowth, and increased mitoses. Fibroadenomas have a more uniform, hypocellular stroma and lack these features. The distinction matters because phyllodes tumors can recur and may require wider excision.

Question 10Surgical Pathology

Which finding in a mismatch repair-deficient colorectal carcinoma most strongly suggests Lynch syndrome rather than a sporadic origin?

  1. CpG island methylator phenotype
  2. MLH1 promoter hypermethylation
  3. BRAF V600E mutation
  4. Loss of MSH2 and MSH6 expression Correct answer.

Explanation

Loss of MSH2 and MSH6 points to a germline mismatch repair defect, most often an MSH2 mutation, and is not explained by sporadic MLH1 silencing. Sporadic MSI-high carcinomas usually show MLH1 and PMS2 loss with MLH1 promoter hypermethylation, often accompanied by BRAF V600E. Testing for these features helps triage referral for genetic counseling.

Question 11Surgical Pathology

Which statement about high-grade prostatic intraepithelial neoplasia (HGPIN) is correct?

  1. Atypical cells lining pre-existing ducts with an intact basal layer Correct answer.
  2. It is defined by invasion of atypical glands into periprostatic fat
  3. It is diagnosed only when cribriform glands show comedonecrosis
  4. It shows complete loss of the basal cell layer

Explanation

HGPIN consists of architecturally benign ducts and acini lined by cytologically atypical cells with an intact basal cell layer. Because the basal layer is preserved, it is not invasive carcinoma and does not by itself require re-excision. Comedonecrosis within a cribriform proliferation indicates intraductal carcinoma rather than HGPIN.

Question 12Surgical Pathology

What is required to diagnose follicular carcinoma of the thyroid?

  1. Capsular or vascular invasion Correct answer.
  2. Papillary architecture with fibrovascular cores
  3. Nuclear grooves and pseudoinclusions
  4. Psammoma bodies within tumor follicles

Explanation

Follicular carcinoma is diagnosed only by demonstrating capsular or vascular invasion after the tumor-capsule interface has been fully submitted and examined. Cytologic atypia alone cannot separate follicular carcinoma from a follicular adenoma. Nuclear grooves, psammoma bodies, and papillary architecture point to papillary carcinoma instead.

Question 13Surgical Pathology

Which histologic feature is typical of small cell carcinoma of the lung?

  1. Nuclear molding, crush artifact, and scant cytoplasm Correct answer.
  2. Large cells with prominent nucleoli and distinct borders
  3. Abundant eosinophilic cytoplasm with keratin pearls
  4. Glandular formation with mucin production

Explanation

Small cell carcinoma is composed of small cells with scant cytoplasm, nuclear molding, finely granular chromatin, and absent or inconspicuous nucleoli. Crush artifact, high mitotic activity, and necrosis are typical. Keratin pearls, mucin production, and prominent nucleoli suggest other histologic types.

Question 14Surgical Pathology

Which combination of findings is most characteristic of clear cell renal cell carcinoma?

  1. Cells with abundant eosinophilic cytoplasm, CK7 positive, CAIX negative
  2. Desmoplastic stroma with irregular malignant ducts
  3. Papillary architecture with foamy macrophages
  4. Clear cells in nests with a delicate capillary network Correct answer.

Explanation

Clear cell renal cell carcinoma forms nests of cells with optically clear cytoplasm surrounded by a delicate capillary network, and it shows diffuse membranous CAIX with loss of chromosome 3p. Papillary architecture with foamy macrophages indicates papillary RCC. Eosinophilic cytoplasm with CK7 positivity suggests chromophobe or another oncocytic tumor.

Question 15Surgical Pathology

Which immunoprofile is expected in high-grade serous carcinoma of the ovary?

  1. PAX8 positive, WT1 positive, aberrant p53 expression Correct answer.
  2. TTF-1 positive, napsin A positive
  3. PAX8 negative, WT1 negative, normal p53
  4. CK7 negative, CK20 positive, CDX2 positive

Explanation

High-grade serous carcinoma derives from fallopian tube epithelium and characteristically expresses PAX8 and WT1 with aberrant p53, reflecting near-universal TP53 mutation. CK20 and CDX2 positivity would indicate a colorectal primary. TTF-1 and napsin A point to lung origin.

Question 16Surgical Pathology

Which finding in a pancreatic resection most strongly favors ductal adenocarcinoma over chronic pancreatitis?

  1. Perineural invasion by malignant glands Correct answer.
  2. Reactive ductal changes with mild nuclear atypia
  3. Lobulocentric inflammation with duct dilatation
  4. Fibrosis with preserved acinar architecture

Explanation

Perineural invasion by cytologically malignant glands within the pancreas is a strong indicator of ductal adenocarcinoma rather than reactive change. Chronic pancreatitis produces fibrosis, lobulocentric inflammation, and reactive ducts with only mild atypia. High-grade PanIN may accompany carcinoma, but true perineural invasion establishes invasion.

Question 17Surgical Pathology

What is the most common activating mutation in gastric gastrointestinal stromal tumors (GISTs)?

  1. NF1 mutation
  2. PDGFRA exon 18
  3. KIT exon 11 Correct answer.
  4. SDHB loss

Explanation

Most gastric GISTs harbor activating mutations in KIT, with exon 11 being the most common site, and this finding predicts response to imatinib. PDGFRA mutations occur in a minority of tumors, often gastric and epithelioid. SDH deficiency and NF1 mutations are associated with syndromic or wild-type GISTs.

Question 18Surgical Pathology

Which immunophenotype is typical of the neoplastic cells of classic Hodgkin lymphoma?

  1. CD138 and CD38 positive
  2. CD45 positive, CD20 strongly positive, CD30 negative
  3. CD15 positive, CD30 positive, CD45 negative Correct answer.
  4. CD3 positive, CD5 positive, CD10 positive

Explanation

Classic Hodgkin lymphoma cells show a characteristic phenotype: CD30 and CD15 positive, CD45 negative, with weak or absent CD20. This contrasts with non-Hodgkin B-cell lymphomas, which are typically CD45 and CD20 positive. T-cell markers and plasma cell markers define other lymphoma categories.

Question 19Surgical Pathology

Which histologic features are characteristic of basal cell carcinoma?

  1. Whorled keratin pearls with intercellular bridges
  2. Squamoid cells with abundant keratohyalin granules
  3. Basaloid nests with peripheral palisading Correct answer.
  4. Atypical melanocytes at the dermoepidermal junction

Explanation

Basal cell carcinoma forms nests of basaloid cells with peripheral palisading and retraction artifact separating tumor from the surrounding stroma. Squamous cell carcinoma instead shows intercellular bridges and keratin pearls. Melanocytic atypia at the junction indicates melanoma in situ.

Question 20Surgical Pathology

Which finding is most typical of pleomorphic adenoma of the parotid gland?

  1. Perineural invasion with cytologic atypia
  2. Epithelial and myoepithelial cells in a chondromyxoid stroma Correct answer.
  3. Oncocytes in solid nests with lymphoid stroma
  4. Basaloid cells with cribriform spaces containing mucin

Explanation

Pleomorphic adenoma contains a mixture of epithelial and myoepithelial cells in a chondromyxoid or myxoid stroma, frequently with PLAG1 rearrangement. The abundant myxochondroid matrix is a key diagnostic clue and is uncommon in other salivary tumors. Perineural invasion and atypia would raise concern for carcinoma ex pleomorphic adenoma.

Question 21Surgical Pathology

A 35-year-old woman has a firm, ill-defined breast mass. The lesion is a uniform spindle cell proliferation infiltrating fat, with nuclear beta-catenin expression and no cytokeratin or p63 reactivity. What is the diagnosis?

  1. Metaplastic carcinoma
  2. Fibromatosis Correct answer.
  3. Phyllodes tumor
  4. Myofibroblastoma

Explanation

Breast fibromatosis is a bland spindle cell proliferation that infiltrates fat, expresses nuclear beta-catenin, and is negative for cytokeratin and p63. The absence of epithelial markers and of cytologic atypia argues against metaplastic carcinoma. Myofibroblastoma is well circumscribed and typically desmin positive.

Question 22Surgical Pathology

A deep soft tissue mass in a young adult harbors a t(X;18) translocation. Which diagnosis is most likely?

  1. Ewing sarcoma
  2. Dermatofibrosarcoma protuberans
  3. Synovial sarcoma Correct answer.
  4. Alveolar rhabdomyosarcoma

Explanation

Synovial sarcoma is defined by the t(X;18) translocation producing an SYT-SSX fusion and typically arises in deep soft tissue of young adults. It is usually positive for EMA and cytokeratins and may show a biphasic pattern with epithelial glands. Other small blue cell sarcomas carry different defining fusions.

Question 23Surgical Pathology

A well-differentiated small intestinal neuroendocrine tumor has 8 mitoses per 2 mm² and a Ki-67 index of 8%. What grade should be assigned?

  1. NET G1
  2. NET G2 Correct answer.
  3. MiNEN
  4. NET G3

Explanation

A mitotic rate between 2 and 20 per 2 mm² or a Ki-67 index between 3% and 20% places a well-differentiated neuroendocrine tumor in grade 2. Grade 1 requires fewer than 2 mitoses per 2 mm² and a Ki-67 below 3%. Grade 3 applies when mitoses exceed 20 per 2 mm² or Ki-67 exceeds 20%.

Question 24Surgical Pathology

Which immunophenotype favors pleural mesothelioma over metastatic lung adenocarcinoma?

  1. Calretinin positive, WT1 positive, MOC-31 negative Correct answer.
  2. TTF-1 positive, napsin A positive, CK7 positive, calretinin negative
  3. MOC-31 positive, Ber-EP4 positive, calretinin negative
  4. CEA positive, CD15 positive, WT1 negative, calretinin negative

Explanation

Mesothelioma typically expresses calretinin, WT1, and D2-40 and is negative for adenocarcinoma markers such as MOC-31, Ber-EP4, and CEA. Lung adenocarcinoma instead expresses TTF-1 and napsin A. A panel combining mesothelial and epithelial markers is required because no single stain is perfectly specific.

Question 25Surgical Pathology

A 55-year-old man has a testicular mass. Histology shows a mixture of small, intermediate, and large cells with no lymphocytic infiltrate, and cytogenetics shows no i(12p). What is the diagnosis?

  1. Embryonal carcinoma
  2. Yolk sac tumor
  3. Classic seminoma
  4. Spermatocytic tumor Correct answer.

Explanation

Spermatocytic tumor occurs in older men, contains three cell populations, lacks the lymphocytic infiltrate of classic seminoma, and does not carry i(12p). It is clinically indolent, and orchiectomy is usually curative. The other germ cell tumors arise from germ cell neoplasia in situ and usually show i(12p).

Question 26Surgical Pathology

Which nuclear feature is most characteristic of papillary thyroid carcinoma?

  1. Optically clear nuclei with grooves and pseudoinclusions Correct answer.
  2. Prominent nucleoli with coarse chromatin and frequent mitoses
  3. Multinucleated giant cells with eosinophilic viral inclusions
  4. Salt-and-pepper chromatin with nuclear molding and crush artifact

Explanation

Papillary thyroid carcinoma is diagnosed by nuclear changes: optical clearing, longitudinal grooves, and intranuclear pseudoinclusions. These features are often widespread even when the architecture is follicular. They are not seen in medullary or anaplastic carcinoma.

Question 27Surgical Pathology

Which histologic finding is characteristic of a Peutz-Jeghers polyp?

  1. Arborizing smooth muscle bands Correct answer.
  2. Sessile serrated crypts with basal dilation and dysplasia
  3. Submucosal lipoma with overlying normal mucosa and no atypia
  4. Dilated mucin-filled glands with abundant inflamed stroma

Explanation

Peutz-Jeghers polyps show a branching, arborizing framework of smooth muscle derived from the muscularis mucosae. The overlying epithelium is usually normal and may show pseudoinvasion. This smooth muscle arborization distinguishes it from juvenile and hyperplastic polyps.

Question 28Surgical Pathology

Which feature best identifies a schwannoma among peripheral nerve sheath tumors?

  1. Antoni A/B areas with Verocay bodies Correct answer.
  2. Mast cells scattered in a myxoid stroma with perineurial cells
  3. Whorled collagen bundles with elastic fibers and calcification
  4. Axonal bundles dispersed throughout a collagenous tumor

Explanation

Schwannomas are encapsulated tumors composed of Antoni A (cellular) and Antoni B (myxoid) areas. Verocay bodies are palisading rows of nuclei around fibrillary processes. Axons are pushed aside rather than incorporated within the tumor.

Question 29Surgical Pathology

Which salivary gland tumor is characterized by oncocytic bilayered epithelium and a lymphoid stroma with germinal centers?

  1. Warthin tumor Correct answer.
  2. Pleomorphic adenoma
  3. Acinic cell carcinoma
  4. Mucoepidermoid carcinoma

Explanation

Warthin tumor (papillary cystadenoma lymphomatosum) has cystic spaces lined by bilayered oncocytic epithelium with a dense lymphoid stroma. Germinal centers are common. It typically arises in the parotid tail of older adults and is often bilateral.

Question 30Surgical Pathology

A breast biopsy shows a solid proliferation of uniform small cells filling and distending lobules, with loss of E-cadherin expression. What is the diagnosis?

  1. Invasive lobular carcinoma
  2. Ductal carcinoma in situ, solid type
  3. Usual ductal hyperplasia
  4. Lobular carcinoma in situ Correct answer.

Explanation

Lobular carcinoma in situ fills and distends terminal duct lobular units with a uniform population of small cells. Loss of E-cadherin is a defining feature. Stromal invasion is absent; when invasion is present, the lesion is invasive lobular carcinoma.

Question 31Surgical Pathology

A lung biopsy shows a non-small cell carcinoma. Which immunoprofile supports adenocarcinoma over squamous cell carcinoma?

  1. TTF-1 positive, napsin A positive Correct answer.
  2. Calretinin positive, WT1 positive, D2-40 positive, p40 negative
  3. CD56 positive, synaptophysin positive, chromogranin positive, TTF-1 negative
  4. CK5/6 positive, p40 positive, TTF-1 negative, napsin A negative

Explanation

Lung adenocarcinoma is typically positive for TTF-1 and napsin A and negative for squamous markers. Squamous cell carcinoma expresses p40 and CK5/6. Neuroendocrine and mesothelial profiles are distinct and should not be used to support adenocarcinoma.

Question 32Surgical Pathology

A 50-year-old woman has a unilateral ovarian mass. Histology shows uniform cells with pale grooved nuclei, Call-Exner bodies, and inhibin positivity. What is the most likely diagnosis?

  1. Dysgerminoma with lymphoid stroma
  2. Brenner tumor with urothelial nests
  3. Ovarian fibroma with spindle cells
  4. Adult granulosa cell tumor Correct answer.

Explanation

Adult granulosa cell tumor is a sex cord-stromal neoplasm with uniform cells, grooved nuclei, and Call-Exner bodies. It is positive for inhibin and may present with estrogenic manifestations. Fibromas, Brenner tumors, and dysgerminomas lack this combination.

Question 33Surgical Pathology

Which immunoprofile favors endometrial serous carcinoma over endometrial endometrioid carcinoma?

  1. p53 aberrant, p16 block positive, ER weak Correct answer.
  2. MLH1 absent, PMS2 absent, ER positive, p53 wild-type pattern
  3. PTEN loss, ARID1A loss, ER positive, p53 wild-type pattern
  4. ER strongly positive, PR strongly positive, p53 wild-type pattern with retained ARID1A

Explanation

Endometrial serous carcinoma typically shows aberrant p53 (overexpression or null pattern), strong block p16 positivity, and weak or negative ER/PR. Endometrioid carcinoma more often retains p53 and expresses ER/PR. PTEN and ARID1A loss are common in endometrioid tumors.

Question 34Surgical Pathology

A 30-year-old woman has a liver mass. Histology shows a central stellate scar, nodular hepatocyte hyperplasia, and thick-walled vessels. What is the diagnosis?

  1. Hepatic hemangioma with cavernous spaces
  2. Focal nodular hyperplasia Correct answer.
  3. Hepatocellular adenoma with beta-catenin activation
  4. Hepatocellular carcinoma with vascular invasion

Explanation

Focal nodular hyperplasia has a central stellate scar with thick-walled vessels and bile ductular reaction. Hepatocytes form nodules without significant atypia. It is benign and usually managed conservatively.

Question 35Surgical Pathology

A 25-year-old woman has a pancreatic mass. Histology shows solid and pseudopapillary areas with uniform cells and hyaline globules; tumor cells show nuclear beta-catenin. What is the diagnosis?

  1. Pancreatic neuroendocrine tumor
  2. Solid pseudopapillary neoplasm Correct answer.
  3. Mucinous cystic neoplasm
  4. Pancreatic ductal adenocarcinoma

Explanation

Solid pseudopapillary neoplasm occurs in young women and shows solid and pseudopapillary architecture with uniform cells. Nuclear beta-catenin accumulation and hyaline globules are characteristic. Ductal adenocarcinoma and neuroendocrine tumors have different morphology and immunophenotypes.

Question 36Surgical Pathology

Which feature in prostatic acinar adenocarcinoma corresponds to Gleason pattern 4?

  1. Fused glands or cribriform architecture Correct answer.
  2. Single cells and cords without gland formation or lumen
  3. Well-formed discrete glands with abundant cytoplasm and rounded lumina
  4. Large comedonecrosis within glands and sheet-like growth

Explanation

Gleason pattern 4 includes fused glands, ill-defined glands, and cribriform architecture. Pattern 3 consists of discrete well-formed glands. Pattern 5 includes single cells, cords, sheets, and comedonecrosis.

Question 37Surgical Pathology

Which finding best supports follicular lymphoma over reactive follicular hyperplasia?

  1. Interfollicular plasmacytosis and vascular proliferation
  2. Follicles of varying size and shape distributed in the cortex
  3. Monotonous follicles with loss of polarization and strong BCL2 expression Correct answer.
  4. Lymphoid follicles with polarized germinal centers and tingible body macrophages

Explanation

Follicular lymphoma shows monotonous follicles that lack polarization and tingible body macrophages. Germinal centers are strongly BCL2 positive, unlike reactive germinal centers. Reactive hyperplasia shows polarized follicles with tingible body macrophages and variable follicle shapes.

Question 38Surgical Pathology

A 15-year-old boy has a diaphyseal bone tumor. Histology shows uniform small round blue cells with membranous CD99 positivity; molecular testing shows an EWSR1-FLI1 fusion. What is the diagnosis?

  1. Mesenchymal chondrosarcoma
  2. Lymphoblastic lymphoma
  3. Osteosarcoma, small cell variant
  4. Ewing sarcoma Correct answer.

Explanation

Ewing sarcoma is a small round blue cell tumor of bone with membranous CD99 and an EWSR1-FLI1 fusion. It typically arises in the diaphysis of children and young adults. Small cell osteosarcoma and mesenchymal chondrosarcoma lack this fusion.

Question 39Surgical Pathology

Which constellation of findings is most consistent with a complete hydatidiform mole?

  1. Chorionic villi with trophoblastic inclusions and normal p57 expression
  2. Diffuse hydropic villi with central cisterns and p57 loss Correct answer.
  3. Triploid karyotype with patchy villous edema and focal trophoblast proliferation
  4. Focal trophoblastic proliferation, scalloped chorionic villi, and fetal parts

Explanation

Complete moles show diffuse villous hydropic change, central cistern formation, and trophoblastic proliferation. They are androgenetic, so p57 expression is lost in cytotrophoblast and villous stroma. Partial moles are triploid, focal, and retain p57.

Question 40Surgical Pathology

A deep thigh mass in a 40-year-old shows myxoid stroma, delicate plexiform capillaries, and lipoblasts; molecular testing shows a FUS-DDIT3 fusion. What is the diagnosis?

  1. Myxoid liposarcoma Correct answer.
  2. Dedifferentiated liposarcoma
  3. Myxofibrosarcoma
  4. Intramuscular myxoma

Explanation

Myxoid liposarcoma has myxoid stroma, a delicate plexiform capillary network, and lipoblasts. It is characterized by FUS-DDIT3 (or EWSR1-DDIT3) fusion. Myxofibrosarcoma lacks this fusion and shows more pleomorphism.

Question 41Cytopathology

According to the Bethesda System, what is the minimum number of well-visualized squamous cells required for an adequate conventional cervical cytology smear?

  1. 5,000
  2. 10,000
  3. 20,000
  4. 8,000 Correct answer.

Explanation

The Bethesda System requires at least 8,000 well-visualized squamous cells on a conventional smear and at least 5,000 on a liquid-based preparation. Below these thresholds, the specimen is unsatisfactory for evaluation unless a qualifying abnormality is present.

Question 42Cytopathology

A cervical Pap test shows squamous cells with enlarged, irregular nuclei, perinuclear halos, and binucleation. Which Bethesda System category is most appropriate?

  1. LSIL Correct answer.
  2. AGC
  3. HSIL
  4. ASC-US

Explanation

Koilocytic change with nuclear enlargement, irregular nuclear contours, halos, and binucleation is the cytologic hallmark of LSIL. ASC-US denotes less definitive atypia, while HSIL shows a higher nuclear-to-cytoplasmic ratio and immature cells.

Question 43Cytopathology

A thyroid FNA shows a follicular lesion with focal nuclear atypia that is insufficient for a diagnosis of follicular neoplasm. Which Bethesda category applies?

  1. Bethesda IV (follicular neoplasm)
  2. Bethesda II (benign)
  3. Bethesda III (AUS/FLUS) Correct answer.
  4. Bethesda I (nondiagnostic)

Explanation

Bethesda III (AUS/FLUS) is used when follicular-patterned cells show atypia that is not sufficient for a follicular neoplasm or suspicious for malignancy. The category carries an approximately 10–30% risk of malignancy.

Question 44Cytopathology

FNA of a well-circumscribed breast mass in a young woman shows cohesive flat sheets of uniform ductal cells and numerous bare bipolar myoepithelial nuclei. What is the most likely diagnosis?

  1. Fibroadenoma Correct answer.
  2. Papillary carcinoma
  3. Invasive ductal carcinoma
  4. Fibrocystic change

Explanation

Fibroadenoma yields cohesive, flat sheets of uniform epithelial cells accompanied by many bare bipolar myoepithelial nuclei. The presence of these myoepithelial cells supports a benign biphasic lesion, whereas carcinoma usually lacks them.

Question 45Cytopathology

In the Paris System for Reporting Urinary Cytology, which finding is a major criterion for high-grade urothelial carcinoma?

  1. Mild nuclear enlargement with fine chromatin
  2. Presence of umbrella cells
  3. N/C ratio greater than 0.7 Correct answer.
  4. Abundant granular cytoplasm

Explanation

The Paris System uses a nuclear-to-cytoplasmic ratio greater than 0.7 as a major criterion for high-grade urothelial carcinoma, along with hyperchromasia and irregular nuclear membranes. Umbrella cells and mild reactive changes are benign findings.

Question 46Cytopathology

FNA of a cervical lymph node shows cohesive clusters of epithelioid histiocytes with necrotic debris and no malignant cells. What is the most likely diagnosis?

  1. Hodgkin lymphoma
  2. Metastatic squamous cell carcinoma
  3. Necrotizing granulomas Correct answer.
  4. Follicular lymphoma

Explanation

Cohesive epithelioid histiocytes with necrotic debris are characteristic of necrotizing granulomatous inflammation, commonly due to mycobacterial or fungal infection. The absence of malignant cells and the presence of necrosis favor a granulomatous process.

Question 47Cytopathology

FNA of a parotid mass shows sheets of oncocytic cells with granular cytoplasm and a background of mature lymphocytes. What is the most likely diagnosis?

  1. Pleomorphic adenoma
  2. Mucoepidermoid carcinoma
  3. Warthin tumor Correct answer.
  4. Acinic cell carcinoma

Explanation

Warthin tumor is characterized by oncocytic epithelial sheets and a lymphoid background, often with cystic debris. It is a benign salivary gland neoplasm that commonly arises in the parotid tail.

Question 48Cytopathology

A Pap smear from a patient with vulvar pruritus shows pseudohyphae and budding yeasts with squamous epithelial cells. Which organism is most likely?

  1. Candida species Correct answer.
  2. Gardnerella vaginalis
  3. Herpes simplex virus
  4. Trichomonas vaginalis

Explanation

Budding yeasts with pseudohyphae in a Pap smear are typical of Candida species, which commonly cause vulvovaginal candidiasis. Trichomonas appears as pear-shaped flagellates, and Gardnerella produces clue cells.

Question 49Cytopathology

A 30-year-old woman has an ASC-US Pap result. What is the preferred next step according to current cervical cancer screening guidelines?

  1. Repeat Pap in 5 years
  2. Immediate colposcopy
  3. High-risk HPV testing Correct answer.
  4. Endocervical curettage

Explanation

Current guidelines use reflex high-risk HPV testing to triage ASC-US because it safely identifies women who need colposcopy. HPV-negative ASC-US can be followed with routine screening rather than immediate colposcopy.

Question 50Cytopathology

Endocervical cytology shows atypical glandular cells, and high-risk HPV testing is positive. Which site is most likely the origin?

  1. Endometrium
  2. Cervix Correct answer.
  3. Ovary
  4. Peritoneum

Explanation

High-risk HPV positivity in atypical glandular cells strongly favors a cervical glandular lesion, including AIS or adenocarcinoma. Endometrial glandular atypia is typically HPV-negative and occurs in older women.