classic labs/findings 3

Question 1

Narrowing of bowel lumen on barium x-ray

Answer 1

“String sign” (Crohn disease)

Question 2

Necrotizing vasculitis (lungs) and necrotizing glomerulonephritis

Answer 2

Granulomatosis with polyangiitis (Wegener; PR3-ANCA/c-ANCA) and Goodpasture syndrome (anti–basement
membrane antibodies)

Question 3

Needle-shaped, ⊝ birefringent crystals

Answer 3

Gout (monosodium urate crystals)

Question 4

Nodular hyaline deposits in glomeruli

Answer 4

Kimmelstiel-Wilson nodules (diabetic nephropathy)

Question 5

Novobiocin response

Answer 5

Sensitive: S epidermidis; resistant: S saprophyticus

Question 6

“Nutmeg” appearance of liver

Answer 6

Chronic passive congestion of liver due to right heart failure or Budd-Chiari syndrome

Question 7

“Onion skin” periosteal reaction

Answer 7

Ewing sarcoma (malignant small blue cell tumor)

Question 8

Optochin response

Answer 8

Sensitive: S pneumoniae; resistant: viridans streptococci (S mutans, S sanguis)

Question 9

Podocyte fusion or “effacement” on electron microscopy

Answer 9

Minimal change disease (child with nephrotic syndrome)

Question 10

Polished, “ivory-like” appearance of bone at cartilage erosion

Answer 10

Eburnation (osteoarthritis resulting in bony sclerosis)

Question 11

Protein aggregates in neurons from hyperphosphorylation of tau protein

Answer 11

Neurofibrillary tangles (Alzheimer disease) and Pick bodies (Pick disease)

Question 12

Psammoma bodies

Answer 12

Papillary serous carcinoma of the endometrium and ovary
Serous papillary thyroid carcinoma
Meningioma
Malignant mesothelioma

Question 13

Pseudopalisading tumor cells on brain biopsy

Answer 13

Glioblastoma multiforme

Question 14

Raised periosteum (creating a “Codman triangle”)

Answer 14

Aggressive bone lesion (eg, osteosarcoma, Ewing sarcoma, osteomyelitis)

Question 15

RBC casts in urine

Answer 15

Glomerulonephritis

Question 16

Rectangular, crystal-like, cytoplasmic inclusions in Leydig cells

Answer 16

Reinke crystals (Leydig cell tumor)

Question 17

Recurrent infections, eczema, thrombocytopenia

Answer 17

Wiskott-Aldrich syndrome

WAS gene mutation; T cells unable to reorganize actin cytoskeleton. X-linked recessive

Question 18

Renal epithelial casts in urine

Answer 18

Intrinsic renal failure (eg, ischemia or toxic injury)

Question 19

Rhomboid crystals, ⊕ birefringent

Answer 19

Pseudogout (calcium pyrophosphate dihydrate crystals)

Question 20

Rib notching (inferior surface, on x-ray)

Answer 20

Coarctation of the aorta

Question 21

Ring-enhancing brain lesion on CT/MRI in AIDS

Answer 21

Toxoplasma gondii, CNS lymphoma

Question 22

Sheets of medium-sized lymphoid cells with scattered pale, tingible body–laden macrophages (“starry sky” histology)

Answer 22

Burkitt lymphoma (t[8:14] c-myc activation, associated with EBV; “starry sky” made up of malignant cells)

Question 23

Silver-staining spherical aggregation of tau proteins in neurons


Answer 23

Pick bodies (Pick disease: progressive dementia, changes in personality)

Question 24

“Soap bubble” in femur or tibia on x-ray

Answer 24

Giant cell tumor of bone (generally benign)

Question 25

“Spikes” on basement membrane, “dome-like” subepithelial deposits

Answer 25

Membranous nephropathy (nephrotic syndrome)

Question 26

Stacks of RBCs

Answer 26

Rouleaux formation (high ESR, multiple myeloma)

Question 27

“Steeple” sign on frontal CXR

Answer 27

Croup (parainfluenza virus)

Question 28

Stippled vaginal epithelial cells

Answer 28

“Clue cells” (Gardnerella vaginalis)

Question 29

Streptococcus bovis bacteremia

Answer 29

Colon cancer

Question 30

“Tennis racket”-shaped cytoplasmic organelles (EM) in Langerhans cells

Answer 30

Birbeck granules (Langerhans cell histiocytosis)

Question 31

Thousands of polyps on colonoscopy

Answer 31

Familial adenomatous polyposis (autosomal dominant, mutation of APC gene)

Question 32

Thrombi made of white/red layers

Answer 32

Lines of Zahn (arterial thrombus, layers of platelets/RBCs)

Question 33

“Thumb sign” on lateral neck x-ray

Answer 33

Epiglottitis (Haemophilus influenzae)

Question 34

Thyroid-like appearance of kidney

Answer 34

Chronic pyelonephritis (usually due to recurrent infections)

Question 35

“Tram-track” appearance of capillary loops of glomerular basement membranes on light microscopy

Answer 35

Membranoproliferative glomerulonephritis

Question 36

Triglyceride accumulation in liver cell vacuoles

Answer 36

Fatty liver disease (alcoholic or metabolic syndrome)

Question 37

^uric acid levels

Answer 37

Gout, Lesch-Nyhan syndrome, tumor lysis syndrome, loop and thiazide diuretics

Question 38

“Waxy” casts with very low urine flow

Answer 38

Chronic end-stage renal disease

Question 39

WBC casts in urine

Answer 39

Acute pyelonephritis

Question 40

WBCs that look “smudged”

Answer 40

CLL (almost always B cell)

Question 41

“Wire loop” glomerular capillary appearance on light microscopy

Answer 41

Diffuse proliferative glomerulonephritis (usually seen with lupus)

Question 42

Yellowish CSF

Answer 42

Xanthochromia (eg, due to subarachnoid hemorrhage) |