Mixed Deck — All ABPATH Topics Flashcards

A clinical laboratory is implementing a new, unmodified, FDA-approved assay. According to CLIA '88, which of the following sets of performance characteristics must the laboratory verify before using the test for patient reporting?

Answer: Accuracy, precision, reportable range, and reference interval.

For an unmodified, FDA-approved test, CLIA '88 requires the laboratory to *verify* the manufacturer's stated performance specifications. This verification process must include demonstrating performance for accuracy, precision, reportable range, and verifying that the manufacturer's reference interval is appropriate for the laboratory's patient population. A full, more extensive validation is required only for laboratory-developed tests or modified FDA-approved tests.

Barrett esophagus is defined histologically by the presence of which type of metaplasia?

Answer: Intestinal metaplasia with goblet cells

Barrett esophagus requires intestinal metaplasia with goblet cells in the distal esophagus, confirmed by Alcian blue stain at pH 2.5.

The reversible cellular change of hydropic swelling results primarily from:

Answer: Failure of the Na+/K+ ATPase pump

Cellular swelling occurs when the Na+/K+ ATPase fails, causing sodium and water influx into the cell.

Apoptosis differs from necrosis primarily in that apoptosis:

Answer: Is energy-dependent and does not incite inflammation

Apoptosis is an ATP-dependent, programmed cell death that leaves the membrane intact and does not provoke inflammation.

What is the key difference between malignant and benign tumors?

Answer: Benign tumors grow slowly, while malignant tumors grow rapidly

The fundamental difference between benign and malignant tumors lies in their biological behavior and potential for harm. Malignant tumors (cancers) exhibit uncontrolled, rapid growth, invade surrounding tissues, and have the capacity to metastasize to distant sites. Benign tumors, in contrast, typically grow slowly, remain localized, and do not invade or metastasize.

A biopsy of a lung mass in a 60-year-old smoker reveals a malignant neoplasm composed of glandular structures. Based on this histologic finding, what is the most appropriate classification for this tumor?

Answer: Adenocarcinoma

A malignant neoplasm of epithelial origin that forms glandular patterns is classified as an adenocarcinoma. [5, 17] Carcinomas are malignant tumors arising from epithelial cells. [5] Squamous cell carcinoma also arises from epithelial cells but is characterized by keratinization and intercellular bridges. Sarcomas are malignant neoplasms arising from mesenchymal tissue (e.g., connective tissue, muscle), and lymphomas are malignancies of lymphocytes. [17]

A biopsy showing non-caseating granulomas in the lung and hilar lymph nodes without organisms most suggests?

Answer: Sarcoidosis

Sarcoidosis classically produces non-caseating granulomas with negative stains for organisms.

Lean methodology in the laboratory primarily aims to:

Answer: Eliminate waste and improve workflow efficiency

Lean focuses on removing non-value-added steps (waste) to streamline laboratory processes.

The Rh antigen most commonly implicated in hemolytic disease of the fetus and newborn is:

Answer: D

Anti-D remains the most clinically significant cause of severe HDFN.

Which of the following conditions is associated with a high erythrocyte sedimentation rate (ESR)?

Answer: Rheumatoid arthritis

The erythrocyte sedimentation rate (ESR) is a non-specific marker of inflammation. It measures the rate at which red blood cells settle in a tube of blood over a specific time. In inflammatory conditions like rheumatoid arthritis, increased levels of acute phase proteins (e.g., fibrinogen) cause red blood cells to aggregate and settle faster, resulting in an elevated ESR.

A 17-year-old athlete suddenly collapses and dies during a basketball game. Autopsy reveals a heart weight of 550 grams (normal <350g) with marked, asymmetric thickening of the interventricular septum. Microscopic examination of the septum shows extensive, haphazardly arranged cardiomyocytes with interstitial fibrosis. Which of the following is the most likely diagnosis?

Answer: Hypertrophic cardiomyopathy

The clinical scenario of a young athlete with sudden cardiac death, combined with the gross finding of asymmetric septal hypertrophy and the key microscopic feature of myofiber disarray, is classic for hypertrophic cardiomyopathy (HCM). HCM is the most common cause of sudden cardiac death in young athletes. The histopathologic hallmarks are myocyte hypertrophy, myofiber disarray, and interstitial fibrosis.

Regeneration, as opposed to repair by scarring, is possible only when:

Answer: The tissue framework and stem cells are intact

Regeneration restores original tissue only when the connective tissue scaffold is preserved and the cells can proliferate.

Lynch syndrome (hereditary non-polyposis colorectal cancer) is caused by germline mutations in which genes?

Answer: MLH1, MSH2, MSH6, PMS2 (MMR genes)

Lynch syndrome results from germline mutations in DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2), leading to microsatellite instability.

A delayed hemolytic transfusion reaction most often results from an anamnestic response to which antibody type?

Answer: Kidd (anti-Jka) antibodies

Kidd antibodies notoriously drop below detection and cause delayed reactions on re-exposure.

Ring sideroblasts seen with Prussian blue staining are a feature of which category of disease?

Answer: Myelodysplastic syndrome

Ring sideroblasts reflect abnormal iron accumulation in mitochondria seen in certain MDS subtypes.

A KRAS mutation in metastatic colorectal cancer predicts:

Answer: Resistance to anti-EGFR monoclonal antibody therapy

Activating KRAS mutations downstream of EGFR confer resistance to cetuximab and panitumumab.

The corrected calcium formula is needed when which protein is abnormal?

Answer: Albumin

Roughly half of serum calcium is albumin-bound, so total calcium must be corrected for low albumin.

Which analyte is best measured in a first-morning urine sample for microalbuminuria screening?

Answer: Albumin-to-creatinine ratio

The albumin-to-creatinine ratio corrects for urine concentration and detects early diabetic nephropathy.

Peripheral palisading of basaloid nuclei and retraction artifact (clefting) between tumor nests and stroma are hallmarks of:

Answer: Basal cell carcinoma

Peripheral nuclear palisading and stromal retraction artifact (clefting) between tumor nests and the surrounding stroma are defining histological features of basal cell carcinoma.

A root cause analysis (RCA) is most appropriately performed after:

Answer: A sentinel event or significant laboratory error

RCA is used to systematically investigate the underlying cause of a serious error or sentinel event.