ASCP CT cheat sheet

Bethesda adequacy: a conventional Pap smear generally needs about 5,000 well-visualized squamous cells; a transformation-zone component is suggested by at least 10 endocervical or squamous metaplastic cells.

NILM includes reactive squamous changes, organisms such as Trichomonas, Candida, bacterial vaginosis, and HSV, plus atrophy; no squamous or glandular epithelial abnormality is present.

ASC-US shows squamous nuclear enlargement about 2.5–3 times the area of a normal intermediate nucleus, mild hyperchromasia, and no definite koilocytosis; management uses HPV triage or repeat testing.

LSIL is defined by koilocytes with perinuclear halos, nuclear enlargement and irregularity, and raisinoid nuclei; it corresponds to HPV cytopathic effect and CIN1.

ASC-H means atypical squamous cells cannot exclude HSIL; cells show high nuclear-to-cytoplasmic ratio and irregular nuclei, and colposcopy is recommended.

HSIL shows high nuclear-to-cytoplasmic ratio, hyperchromasia, irregular nuclear membranes, and loss of polarity; syncytial clusters and cannonballs occur in liquid-based preparations.

AGC denotes atypical glandular cells; subclassify as favor neoplastic when possible, and treat endometrial cells in a postmenopausal woman without hormone therapy as abnormal.

Squamous cell carcinoma shows tumor diathesis with necrotic debris, blood, and proteinaceous material, plus marked pleomorphism, hyperchromasia, and keratinization.

HSV cytology shows multinucleation, nuclear molding, chromatin margination, and Cowdry A inclusions; these changes can mimic dysplasia but are viral cytopathic effect.

In sputum and bronchoalveolar lavage, alveolar macrophages confirm that the lower respiratory tract was sampled and support specimen adequacy.

Reactive bronchial cells retain cilia and terminal bars, have uniform nuclei, and may appear columnar; these features help separate them from adenocarcinoma.

Small cell carcinoma shows scant cytoplasm, nuclear molding, salt-and-pepper chromatin, crush artifact, necrosis, and mitotic activity.

Adenocarcinoma forms three-dimensional clusters with mucin and prominent nucleoli, whereas mesothelial cells show intercellular windows and two-tone cytoplasm.

Under the Paris System for urine, HGUC requires nuclear-to-cytoplasmic ratio greater than 0.5, hyperchromasia, and irregular nuclear membranes.

Decoy cells are polyomavirus-infected urothelial cells with ground-glass nuclei and high nuclear-to-cytoplasmic ratio; they can mimic high-grade urothelial carcinoma.

Reactive mesothelial cells in body fluids have two-tone cytoplasm and windows; adenocarcinoma clusters show three-dimensional crowding, mucin, and marked atypia.

CSF malignant cells show high nuclear-to-cytoplasmic ratio and scant cytoplasm; blasts must be distinguished from reactive lymphocytes and correlated with clinical findings.

Hemosiderin-laden macrophages in BAL indicate alveolar hemorrhage; brown cytoplasmic pigment stains with Prussian blue, and eosinophils suggest eosinophilic pneumonia.

Thyroid Bethesda categories are I nondiagnostic, II benign, III AUS/FLUS, IV follicular neoplasm, V suspicious for malignancy, and VI malignant.

Papillary thyroid carcinoma shows nuclear grooves, intranuclear pseudoinclusions, powdery chromatin, and psammoma bodies.

Follicular neoplasm cannot be separated from follicular adenoma by cytology; histologic capsular or vascular invasion is required for carcinoma diagnosis.

Medullary thyroid carcinoma shows salt-and-pepper chromatin, plasmacytoid or spindle cells, and amyloid; calcitonin immunostaining supports the diagnosis.

Hashimoto thyroiditis yields Hürthle cells and lymphocytes; the mixture can mimic a Hürthle cell neoplasm.

Pleomorphic adenoma aspirates show biphasic epithelial and myoepithelial cells with fibrillary chondromyxoid stroma.

Warthin tumor shows oncocytic epithelial cells and abundant lymphocytes, often with cystic debris, and commonly arises in the parotid gland.

Breast fibroadenoma yields biphasic cohesive clusters and bare nuclei; carcinoma yields cohesive atypical clusters with nuclear pleomorphism.

Lymph node FNA may show granulomatous inflammation, lymphoma, or metastatic carcinoma; flow cytometry and immunohistochemistry are useful ancillary tests.

Papanicolaou stain sequence: hematoxylin for nuclei, water and alcohol rinses, OG-6 and EA-50 for cytoplasm, then alcohol dehydration and xylene clearing.

Immediate wet fixation in 95% ethanol prevents air-drying artifact; delayed fixation causes nuclear enlargement and pseudokeratinization that can mimic dysplasia.

Liquid-based cytology collects cells in fixative and prepares a monolayer slide; it reduces air-drying, obscuring blood, and mucus compared with conventional smears.

A cell block concentrates cells into a formalin-fixed pellet and permits H&E review, immunohistochemistry, and special stains.

CLIA limits a cytotechnologist to screening no more than 100 gynecologic slides in a 24-hour period; workload must be documented.

Specimens with absent or incorrect patient identification, no required fixative, or leaked containers may be rejected; document the event and request recollection.

Special stains include GMS for fungi, AFB for mycobacteria, PAS for glycogen and mucin, and mucicarmine for mucin.

Centrifuge tubes must be balanced, and speed and time must follow the protocol to avoid cell damage and inconsistent slides.

Immunohistochemistry batches require positive and negative controls to validate staining performance.

CLIA requires re-screening of at least 10% of negative gynecologic cytology cases by a qualified supervisor or cytotechnologist.

When HSIL or carcinoma is diagnosed, prior negative gynecologic slides from the previous five years are reviewed in the lookback process.

Sensitivity equals true positives divided by true positives plus false negatives; it measures the proportion of diseased cases correctly identified.

Specificity equals true negatives divided by true negatives plus false positives; it measures the proportion of non-diseased cases correctly identified.

The ASC-US/LSIL ratio and HPV positivity rate are monitoring metrics; outliers trigger review of screening and interpretive practices.

Proficiency testing and CAP inspections assess laboratory performance; deficiencies require documented corrective action.

Root cause analysis identifies process failures, implements corrective actions, and monitors effectiveness to prevent recurrence.

Cytology-histology correlation compares cytology diagnoses with subsequent tissue diagnoses; discordances are reviewed for sampling or interpretive errors.

OSHA formaldehyde permissible exposure limit is 0.75 ppm as an 8-hour time-weighted average, with a 2 ppm short-term exposure limit over 15 minutes.

OSHA xylene permissible exposure limit is 100 ppm as an 8-hour time-weighted average; use local exhaust ventilation and appropriate PPE.

Clinical cytology laboratories use BSL-2 practices: PPE, hand hygiene, restricted access, and safe handling of potentially infectious specimens.

Bloodborne pathogen precautions treat all specimens as infectious; sharps go into puncture-resistant containers, and exposures are reported.

Formalin and xylene are hazardous wastes; they must be segregated, labeled, and disposed of through a licensed vendor, never poured down a drain.

Chemical spills require evacuation, ventilation, PPE, and a spill kit; the event is reported and documented.

Flammable solvents are stored in approved cabinets with bonding and grounding to prevent ignition.

Needle safety includes no recapping, use of safety-engineered devices, and immediate reporting of needlesticks or mucous membrane exposures.

Bethesda adequacy: about 5,000 well-visualized squamous cells for conventional smears; transformation zone sampling suggested by at least 10 endocervical or metaplastic cells.

LSIL koilocytes show perinuclear halos, nuclear enlargement, irregular contours, and raisinoid nuclei.

ASC-H requires colposcopy because HSIL cannot be excluded.

HSIL shows high nuclear-to-cytoplasmic ratio, hyperchromasia, irregular membranes, and loss of polarity.

AGC with endometrial cells in a postmenopausal woman is abnormal and needs endometrial evaluation.

Squamous cell carcinoma shows tumor diathesis, necrosis, marked pleomorphism, and keratinization.

Alveolar macrophages support lower respiratory tract sampling in sputum and BAL.

Small cell carcinoma shows nuclear molding, salt-and-pepper chromatin, crush artifact, and scant cytoplasm.

Urine HGUC requires nuclear-to-cytoplasmic ratio greater than 0.5, hyperchromasia, and irregular nuclear membranes.

Decoy cells are polyomavirus-infected urothelial cells with ground-glass nuclei and can mimic malignancy.

Reactive mesothelial cells show two-tone cytoplasm and intercellular windows.

Hemosiderin-laden macrophages indicate alveolar hemorrhage and stain with Prussian blue.

Thyroid Bethesda categories are I nondiagnostic, II benign, III AUS/FLUS, IV follicular neoplasm, V suspicious, and VI malignant.

Papillary thyroid carcinoma shows nuclear grooves, pseudoinclusions, powdery chromatin, and psammoma bodies.

Follicular carcinoma requires histologic capsular or vascular invasion; cytology cannot reliably distinguish it from adenoma.

Medullary thyroid carcinoma shows salt-and-pepper chromatin, amyloid, and calcitonin positivity.

Pleomorphic adenoma shows biphasic cells and fibrillary chondromyxoid stroma.

Warthin tumor shows oncocytic cells and lymphocytes, often with cystic debris.

Pap stain uses hematoxylin, OG-6, and EA-50, followed by alcohol dehydration and xylene clearing.

Immediate 95% ethanol fixation prevents air-drying artifact.

CLIA limits cytotechnologist screening to 100 gynecologic slides per 24 hours.

Cell blocks permit H&E, immunohistochemistry, and special stains.

Unlabeled or unfixed specimens may be rejected and recollection requested.

At least 10% of negative gynecologic cases are re-screened as required quality control.

HSIL or carcinoma diagnosis triggers review of prior negative gynecologic slides from the previous five years.

Sensitivity = TP/(TP + FN).

Specificity = TN/(TN + FP).

Cytology-histology correlation identifies sampling and interpretive discordances.

Formaldehyde OSHA limit is 0.75 ppm as an 8-hour TWA and 2 ppm as a 15-minute STEL.

Xylene OSHA limit is 100 ppm as an 8-hour TWA.

Clinical cytology uses BSL-2 practices and treats all specimens as potentially infectious.

Formalin and xylene are hazardous wastes and must go through a licensed vendor.

Sharps go into puncture-resistant containers, and needlesticks are reported immediately.