classic labs/findings 3 Flashcards
Narrowing of bowel lumen on barium x-ray
“String sign” (Crohn disease)
Necrotizing vasculitis (lungs) and necrotizing glomerulonephritis
Granulomatosis with polyangiitis (Wegener; PR3-ANCA/c-ANCA) and Goodpasture syndrome (anti–basement
membrane antibodies)
Needle-shaped, ⊝ birefringent crystals
Gout (monosodium urate crystals)
Nodular hyaline deposits in glomeruli
Kimmelstiel-Wilson nodules (diabetic nephropathy)
Novobiocin response
Sensitive: S epidermidis; resistant: S saprophyticus
“Nutmeg” appearance of liver
Chronic passive congestion of liver due to right heart failure or Budd-Chiari syndrome
“Onion skin” periosteal reaction
Ewing sarcoma (malignant small blue cell tumor)
Optochin response
Sensitive: S pneumoniae; resistant: viridans streptococci (S mutans, S sanguis)
Podocyte fusion or “effacement” on electron microscopy
Minimal change disease (child with nephrotic syndrome)
Polished, “ivory-like” appearance of bone at cartilage erosion
Eburnation (osteoarthritis resulting in bony sclerosis)
Protein aggregates in neurons from hyperphosphorylation of tau protein
Neurofibrillary tangles (Alzheimer disease) and Pick bodies (Pick disease)
Psammoma bodies
Papillary serous carcinoma of the endometrium and ovary
Serous papillary thyroid carcinoma
Meningioma
Malignant mesothelioma
Pseudopalisading tumor cells on brain biopsy
Glioblastoma multiforme
Raised periosteum (creating a “Codman triangle”)
Aggressive bone lesion (eg, osteosarcoma, Ewing sarcoma, osteomyelitis)
RBC casts in urine
Glomerulonephritis
Rectangular, crystal-like, cytoplasmic inclusions in Leydig cells
Reinke crystals (Leydig cell tumor)
Recurrent infections, eczema, thrombocytopenia
Wiskott-Aldrich syndrome
WAS gene mutation; T cells unable to reorganize actin cytoskeleton. X-linked recessive
Renal epithelial casts in urine
Intrinsic renal failure (eg, ischemia or toxic injury)
Rhomboid crystals, ⊕ birefringent
Pseudogout (calcium pyrophosphate dihydrate crystals)
Rib notching (inferior surface, on x-ray)
Coarctation of the aorta
Ring-enhancing brain lesion on CT/MRI in AIDS
Toxoplasma gondii, CNS lymphoma
Sheets of medium-sized lymphoid cells with scattered pale, tingible body–laden macrophages (“starry sky” histology)
Burkitt lymphoma (t[8:14] c-myc activation, associated with EBV; “starry sky” made up of malignant cells)
Silver-staining spherical aggregation of tau proteins in neurons

Pick bodies (Pick disease: progressive dementia, changes in personality)
“Soap bubble” in femur or tibia on x-ray
Giant cell tumor of bone (generally benign)
“Spikes” on basement membrane, “dome-like” subepithelial deposits
Membranous nephropathy (nephrotic syndrome)
Stacks of RBCs
Rouleaux formation (high ESR, multiple myeloma)
“Steeple” sign on frontal CXR
Croup (parainfluenza virus)
Stippled vaginal epithelial cells
“Clue cells” (Gardnerella vaginalis)
Streptococcus bovis bacteremia
Colon cancer
“Tennis racket”-shaped cytoplasmic organelles (EM) in Langerhans cells
Birbeck granules (Langerhans cell histiocytosis)
Thousands of polyps on colonoscopy
Familial adenomatous polyposis (autosomal dominant, mutation of APC gene)
Thrombi made of white/red layers
Lines of Zahn (arterial thrombus, layers of platelets/RBCs)
“Thumb sign” on lateral neck x-ray
Epiglottitis (Haemophilus influenzae)
Thyroid-like appearance of kidney
Chronic pyelonephritis (usually due to recurrent infections)
“Tram-track” appearance of capillary loops of glomerular basement membranes on light microscopy
Membranoproliferative glomerulonephritis
Triglyceride accumulation in liver cell vacuoles
Fatty liver disease (alcoholic or metabolic syndrome)
^uric acid levels
Gout, Lesch-Nyhan syndrome, tumor lysis syndrome, loop and thiazide diuretics
“Waxy” casts with very low urine flow
Chronic end-stage renal disease
WBC casts in urine
Acute pyelonephritis
WBCs that look “smudged”
CLL (almost always B cell)
“Wire loop” glomerular capillary appearance on light microscopy
Diffuse proliferative glomerulonephritis (usually seen with lupus)
Yellowish CSF
Xanthochromia (eg, due to subarachnoid hemorrhage)