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NuclearMed Flashcards

1
Q

Gallium-67 dose? Gamma energies? Half-life? Time to imaging?

A

5 mCi (inflam). 10 mCi (tumor). 93, 184, 296, 388 keV. 78 hrs. 6, 24 (inflam). 48-72 (tumor).

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2
Q

Gallium-67 mechanism of uptake?

A

Fe analog via transferrin.

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3
Q

Gallium-67 Normal distribution?

A

Liver > spleen, marrow, bone. Variable: breast, bowel, salivary glands, lacrimal glands.

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4
Q

I-131 dose? Gamma energies? Half-life? Time to imaging?

A

2 mCi. 364 keV. half-life 8 days. 48 hrs.

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5
Q

I-131 mechanism of uptake?

A

Iodine. Thyroid uptake,TSH-mediated

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6
Q

I-131 Normal distribution?

A

Stomach, GI, bladder. Variable: salivary, nasopharynx,

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7
Q

I-131 MIBG dose? Gamma energies? Half-life? Time to imaging?

A

2 mCi. 364 keV. 8 days. 48 hrs.

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8
Q

I-131 MIBG mechanism of uptake?

A

Guanethidine analog. Norepinephrine reuptake.

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9
Q

I-131 MIBG normal distribution?

A

Liver > spleen. Variable: salivary, lung, GI, bladder, skeletal muscle, heart.

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10
Q

I-123 MIBG dose? Gamma energies? Half-life? Time to imaging?

A

1-10 mCi. 159 keV. 13 hrs. 24 hrs.

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11
Q

I-123 MIBG normal distribution?

A

Liver > spleen. Variable: salivary, lung, GI, bladder, skeletal muscle, heart.

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12
Q

In-111 octreoscan dose? Gamma energies? Half-life? Time to imaging?

A

6 mCi. 172, 247 keV. 67 hrs. 4, 24 hrs.

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13
Q

Octreoscan mechanism of uptake?

A

Somatostatin analog. Neuroendocrine tumors.

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14
Q

In-111 octreoscan normal distribution?

A

Intense renal cortex. Spleen, liver, pituitary, salivary, GI, bladder. Variable: breast, thyroid.

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15
Q

FDG-PET dose? Gamma energies? Half-life? Time to imaging?

A

10-15 mCi. 511 keV. 2 hrs. 1 hr.

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16
Q

FDG-PET mechanism of uptake?

A

Glucose analog. Active transport into cell. Phosphorylated and trapped.

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17
Q

FDG-Pet normal distribution

A

Intense urinary activity and cerebral cortex. GU, liver, spleen, marrow. Variable: thyroid, cardiac, GI, muscle.

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18
Q

In-111 WBC dose? Gamma energies? Half-life? Time to imaging?

A

0.5 mCi. 172, 247 keV. 67 hrs. 24 hrs.

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19
Q

In-111 WBC mechanism of uptake?

A

WBC localized at infection.

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20
Q

In-111 WBC normal distribution?

A

Spleen&raquo_space; Liver > marrow. No renal or GI activity.

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21
Q

Tc-99 WBC dose? Gamma energies? Half-life? Time to imaging?

A

20 mCi. 140 keV. 6 hrs. 1-4, 24 hrs.

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22
Q

Intense cardiac activity radiotracer?

A

MIBG. PET.

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23
Q

Intense spleen activity radiotracer?

A

WBC.

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24
Q

Intense renal activity radiotracer?

A

Octreotide.

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25
Q

Lacrimal activity?

A

Gallium-67.

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26
Q

For about __ months after hip replacement surgery, the bone around the prosthesis is expected to have increased osteoblastic activity.

A

6 months.

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27
Q

Refers to a hot spot at the tip of a prosthesis and two areas of increased uptake at the proximal end.

A

Toggle sign. Prosthetic loosening.

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28
Q

Three phases of bone scan osteomyelitis?

A

First phase: Early arterial flow, seconds after injection. Second phase: Blood pool, few minutes after injection.Third phase: Bone labeling, 3 or more hours after injection. All three positive in infection.

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29
Q

Contraindications to perfusion lung scanning include

A

Severe pulmonary hypertension. Allergy to human serum albumin products.

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30
Q

Common indication for V/Q scans

A

Suspected PE. Preoperative estimates of lung function. To evaluate right-to-left shunts. Serial assessment of inflammatory lung disease.

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31
Q

When should a V/Q scan be ordered over CTA?

A

Low clinical probability. Normal CXR is normal. Pregnant patient. Contraindication to iodinated contrast.

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32
Q

Normal ventilation scans

A

Homogeneous radiopharmaceutical distribution throughout both lungs on all three phases: Initial breath. Equilibrium. Washout.

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33
Q

Retention (trapping) of xenon in the lungs in a focal or diffuse pattern is an indication of

A

Obstructive lung disease.

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34
Q

Normal perfusion scans

A

Well-defined margins of both lungs on all views. Sharply defined costophrenic angles.

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35
Q

Hampton hump

A

Wedge-shaped, pleural-based infarct on CXR.

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36
Q

Westermark sign

A

Wedge-shaped area of oligemia.

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37
Q

Most common but nonspecific CXR finding of PE

A

Atelectasis or opacities in the region of emboli. Elevated diaphragm, small pleural effusion, and/or prominent hilum are also frequently seen.

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38
Q

Two moderate (25-50%) or four small (<25%) perfusion defects are equivalent to

A

Full-segment defect.

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39
Q

Perfusion defect that demonstrates normal ventilation is termed a

A

Mismatched defect.

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40
Q

Perfusion defects that match ventilation and CXR abnormalities in size and location are called

A

Triple match defects.

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41
Q

Stripe sign.

A

Central perfusion defects with a rim or stripe of increased activity around them. Less than 10% probability of PE.

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42
Q

V/Q scan PIOPED categories?

A

High (2 or more mismatched perfusion segments). Intermediate. Low. Very low. Normal.

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43
Q

Ventilation scan signs in COPD?

A

Delayed wash-in and delayed washout.

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44
Q

Perfusion defects that are significantly larger than the CXR abnormality are

A

Higher probability for PE.

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45
Q

Three principle coronary artery distributions of the LV

A

Left anterior descending artery (LAD). Left circumflex artery (LCX). Posterior descending artery (PDA).

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46
Q

Pharmocologic stress agents in myocardial perfusion imaging?

A

Adenosine. Dipyridamole (if bronchospasm may give dobutamine).

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47
Q

At what percent stenosis can pharmocologic agents not dilate effectively?

A

> 50% stenosis.

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48
Q

Tc-99m Sestamibi is taken up by perfused myocardium by

A

Passive diffusion. Bound in myocyte, mostly within myocardial mitochondria.

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49
Q

Hibernating Myocardium

A

Severe ischemia with high-grade stenosis may be slow to reverse on Tl-201 rest imaging after stress. Respond to revascularization procedures. Perfusion-metabolism mismatch.

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50
Q

Stunned Myocardium

A

Temporarily damaged cells around infarct. Generally is hypokinetic or akinetic. Will not uptake Tl-201 until recovery several weeks later. Normal perfusion.

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51
Q

Solitary palpable thyroid nodules are best evaluated initially

A

FNA.

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52
Q

Discordant thyroid nodule

A

Increased Tc-99m-O4 uptake but decreased I-123 uptake (lost ability to organify iodine). Increased risk of malignancy.

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53
Q

Measurement of the RAIU is usually indicated for one of three reasons:

A

Differentiation of Graves disease (uptake high, usually >35% at 24 hours) from subacute or factitious hyperthyroidism (uptake usually < 2%). Calculation of radioactive iodine dose for treatment of Graves disease. Assessment of suspected toxic multinodular goiters.

54
Q

Lingual thyroid pediatric patients are at high risk of developing

A

Hypothyroidism, with an estimated risk of ~30%.

55
Q

Hyperthyroidism causes?

A

Graves disease (diffuse toxic goiter) is most common. Subacute or painless thyroiditis. Toxic nodular goiter. Factitious hyperthyroidism.

56
Q

Substernal goiter imaging?

A

I-123. Due to large blood pool, Tc-99m-O4 is not useful with substernal goiters.

57
Q

Multinodular goiter

A

Clinical term for adenomatous hyperplasia. Multiple, discrete hot nodules on a background of normal or cool parenchyma. Photopenic regions should be palpated.

58
Q

All types of thyroiditis are characterized by

A

Rapid, asymmetric glandular enlargement with or without nodularity. Subacute viral patients have a very low RAIU.

59
Q

Graves disease

A

Most common cause of hyperthyroidism. Autoimmune disorder, thyroid-stimulating antibodies cause hyperplasia and hyperfunction of thyroid gland.

60
Q

Acute (suppurative) thyroiditis

A

Bacterial infections caused by Streptococcus, Staphylococcus, or Pneumococcus. Fever, severe sore throat, and asymmetric swelling. May result in sepsis from hematogenous spread or extend into mediastinum via fascial planes.

61
Q

Subacute (viral) thyroiditis (de Quervain or granulomatous thyroiditis).

A

Thyroid pain and hyperthyroidism following upper respiratory infection. Disrupted gland releases thyroid hormone. Iodine uptake is usually decreased or absent in acute stages.

62
Q

Hashimoto thyroiditis

A

Most common cause of goiter and primary hypothyroidism in adults in developed countries. Autoimmune disorder with circulating antithyroid antibody.

63
Q

Riedel thyroiditis

A

Rare inflammatory fibrosiS that involves thyroid and commonly extends into neck. Radionuclide uptake is absent (cold) in involved areas.

64
Q

Secondary hyperthyroidism may develop in patients with

A

Hydatidiform moles or choriocarcinoma (secrete HCG). Subunit of HCG is similar to TSH, which may directly stimulating thyroid.

65
Q

Single cold nodules have a _______ incidence of malignancy, whereas malignancy is exceedingly rare in hot nodules.

A

10% to 15%.

66
Q

Thyroid nodule differential

A

Follicular adenoma. Adenomatous hyperplasia. Thyroid cysts. Hemorrhagic cyst.

67
Q

Most common benign neoplasm of the thyroid and represents about 20% of thyroid nodules.

A

Follicular adenoma.

68
Q

Adenomatous nodules, also called ________, are not true neoplasms but are the result of cycles of hyperplasia and involution of a thyroid lobule.

A

Colloid nodules.

69
Q

Signs Suggesting Benign Etiology of Thyroid Nodules

A

Extensive cystic component. Multiple nodules. Hot on radionuclide scan. Peripheral calcification. Shrinkage in size following levothyroxine suppression hormone therapy. Sudden onset. Female gender. Older patient.

70
Q

Signs Suggesting Malignancy of Thyroid Nodules

A

Solid nodule. Cold on radionuclide scan.Irregular contour.Poor margination.Size >4 to 5 cm.

71
Q

Thyroid malignancies

A

Papillary carcinoma. Follicular carcinoma. Medullary thyroid carcinoma. Anaplastic carcinoma.

72
Q

This thyroid malignancy does not take up I-131?

A

Medullary thyroid carcinoma.

73
Q

Most authorities agree with postthyroidectomy ablation in primary thyroid tumors that are > _____ cm?

A

> 1.5 cm.

74
Q

The patient should be hypothyroid with a serum TSH greater than_______ prior to whole body I-131 imaging or ablation,

A

40 IU/Ml.

75
Q

Radioiodine therapy side effects?

A

Sialoadenitis. Xerostomia. Pulmonary fibrosis. Leukemia.

76
Q

Ectopic locations for abnormal parathyroid tissue include:

A

Thymus (10% to 15%). Posterior mediastinum (5%). Retroesophageal (1%). Within carotid sheath (1%). Parapharyngeal (0.5%).

77
Q

Sestamibi and Tetrofosmin Imaging of parathyroid adenoma?

A

Immediate and delayed images of neck and mediastinum. May be cold on initial imaging. Hot on delayed (1-2 hours) imaging. Normal thyroid gland washes out.

78
Q

Which parathyroid glands are more commonly ectopic?

A

Inferior parathyroid glands (from third branchial pouch along with thymus). Usually within mediastinum.

79
Q

Positive GI bleeding studies demonstrate three cardinal findings:

A

Focal activity appears out of nowhere. Activity persists and may increase with time. Activity moves with peristalsis antegrade, retrograde, or in both directions.

80
Q

Meckel Scan

A

Tc-99mO4. Activity concentrates within right lower quadrant or mid abdomen in synchrony with stomach (ectopic gastric mucosa).

81
Q

Liver/Spleen Scan

A

Tc-99m-radiolabeled albumin or sulfur colloid. RES cells phagocytize colloid particles.

82
Q

FNH sulfur colloid scan features

A

Isointense or hotter than liver parenchyma.

83
Q

Heat-Damaged Red Blood Cell Scan

A

Tc-99m-labeled heat damaged red blood cells are preferentially extracted from circulation by splenic tissue. Useful for: Polysplenia. Splenosis. Accessory splenic tissue.

84
Q

Normal HIDA scan (Tc-mebrofenin)

A

Activity should be seen in major extrahepatic ducts, gallbladder, and small bowel within 1 hour.

85
Q

Hallmark of acute cholecystitis by cholescintigraphy is

A

Nonvisualization of gallbladder at both 1- and 4-hour intervals or 30 minutes after morphine administration.

86
Q

Chronic cholecystitis scintigraphy features

A

Gallbladder is not visualized at 1 hour but is seen by 4 hours.

87
Q

Rim sign on hepatobiliary scan images

A

Band of increased activity around gallbladder fossa. Represents poor excretion of radiotracer from inflamed hepatocytes. Usually associated with gangrenous cholecystitis

88
Q

Normal gallbladder ejection fraction is greater than

A

35%.

89
Q

Acalculous biliary disease

A

Chronic acalculous cholecystitis. Cystic duct syndrome. Gallbladder dyskinesis.

90
Q

CCK-assisted cholescintigraphy in acalculous biliary disease demonstrates

A

Decreased gallbladder contraction. Decreased gallbladder ejection fraction.

91
Q

Which scintigraphy study is used in diagnosing liver cavernous hemangiomas?

A

Tc-99m-labeled red blood cells using an in vitro labeling technique.

92
Q

________ is the agent of choice for imaging kidneys in moderate to severe renal failure.

A

Tc-99m-MAG3.

93
Q

Agent of choice for renal cortical imaging?

A

Tc-99m-DMSA has minimal urinary excretion (<5%) and high cortical binding (50%).

94
Q

Radiotracers used to assess GFR and ERPF (plasma flow)?

A

GFR with Tc-99m-DTPA. ERPF with Tc-99m-MAG3.

95
Q

Renal vein thrombosis scintigraphic findings?

A

Decreased perfusion of enlarged kidney with prolonged cortical retention of tracer.

96
Q

Renal transplant complication timeline?

A

ATN 1st week. Urinomas early. Acute rejection 2nd-4th week. Lymphoceles several weeks. Chronic rejection later.

97
Q

ACEi effect on RAS?

A

Angiotensin II causes constriction of efferent arteriole. ACEi blocks Angiotensin II. In RAS ACEi causes relaxation of constricted efferent arteriole, decreasing GFR.

98
Q

Ga-67 imaging is the radionuclide procedure of choice in what patient population?

A

Immunocompromised patients. Patients with FUO.

99
Q

_________ is the radionuclide procedure of choice for diagnosing osteomyelitis.

A

Three-phase bone scintigraphy.

100
Q

Three-phase bone scan findings in osteomyelitis?

A

Focal hyperperfusion. Focal hyperemia. Focally increased bony uptake on delayed (2 to 4 hours postinjection).

101
Q

Can all produce a positive three-phase bone scan, even in the absence of infection.

A

Fractures. Orthopedic hardware. Neuropathic joint.

102
Q

Pores of Kohn

A

Connect adjacent alveoli.

103
Q

Canals of Lambert

A

Connect alveoli with respiratory, terminal, and preterminal bronchioles.

104
Q

Typical V/Q scan finding for PE

A

Mismatched segmental or subsegmental distribution pattern, usually peripheral and wedge shaped in nature.

105
Q

Xenon-133 properties

A

Half-life of 5.3 days. Beta emitter. Photon energy 81 keV. Trachea is critical organ. Should be performed before perfusion lung scans due to Compton scatter from Tc-99m.

106
Q

Patients who should receive fewer particles of Tc-99m-MAA?

A

Pulmonary hypertension. Right to left shunts. Children.

107
Q

Standard cisternogram features

A

Intrathecal indium-111-DTPA. Ascends to basilar cisterns in about 4 hours. Flows over convexities within 24 hours in normals.

108
Q

NPH cisternogram features

A

Early localization of activity within lateral ventricles persisting beyond 24 hours. Delayed clearance over convexities.

109
Q

Procedure of choice for CSF leak

A

Cisternogram.

110
Q

Classic findings in PET brain imaging of Alzheimer’s disease

A

Bilateral temporoparietal defects.

111
Q

PET brain imaging basics of brain tumors

A

High-grade tumors are hypermetabolic. Low-grade tumors are hypometabolic (except juvenile pilocystic astrocytoma).

112
Q

FDG activity in gallbladder bed suggests

A

Acute or chronic cholecystitis. Gallbladder cancer. Adjacent liver tumor.

113
Q

Common brown fat location?

A

Symmetric uptake in paraspinal regions, mediastinum, neck, and supraclavicular area.

114
Q

Most malignant tumors have an SUV of

A

2.5 to 3.0.

115
Q

Physiologic activity usually has an SUV of

A

0.5 to 2.5.

116
Q

PET is utilized in oncology for three major indications:

A

Initial staging. Evaluation of response to treatment. Assessment for recurrence.

117
Q

Malignant pulmonary nodule at PET imaging

A

SUV greater than 2.5 is considered indicative of malignancy. SUV under 1.5 is considered a benign nodule.

118
Q

With small nodules less than _______cm, the partial volume averaging effect may falsely lower the SUV below 2.5, even though the nodule is malignant.

A

less than 1.5 cm

119
Q

PET false-positives for malignant pulmonary nodule

A

Tuberculosis, Fungal infections. Sarcoidosis.

120
Q

Pulmonary nodule false-negative cases are usually hypometabolic malignancies, such as

A

Bronchoalveolar carcinoma. Carcinoid tumor.

121
Q

Radiation pneumonitis is metabolically active in the first ___ months following radiotherapy, making detection of tumor recurrence by PET difficult

A

6 months

122
Q

PET false positives for lymphoma search

A

Hypermetabolic sarcoidosis. Tuberculosis. Pyogenic abscesses. Histoplasmosis and other fungal infections. Discitis.

123
Q

Diffuse splenic activity greater than that of _______ is consistent with diffuse lymphomatous infiltration of the spleen.

A

Liver activity.

124
Q

Preferred diagnostic modality for melanoma region lymph node involvement

A

Sentinel lymph node mapping.

125
Q

Benign causes of distal esophagus PET activity

A

Distal esophagitis. Gastric reflux. Barrett’s esophagus. Hiatal hernia. Retained saliva.

126
Q

Tumor activity more than ____ times that of white matter or more than ____ times that of gray matter has very high sensitivity and specificity for malignancy

A

1.5 times white matter. 0.6 times gray matter.

127
Q

PET features of Alzheimer disease

A

Bilateral hypometabolism of temporal and parietal lobes. Sparing of visual and motor cortices.

128
Q

PET featurs of Pick disease

A

Hypometabolic areas involving both frontal and anterior temporal lobes.

129
Q

PET features of Multi-infarct dementia

A

Multiple defects throughout brain parenchyma without sparing of visual and motor cortices.

130
Q

PET features of Parkinson disease

A

High FDG activity in lentiform nuclei and thalami related to lack of dopaminergic inhibition. Caudate nuclei are spared.

131
Q

PET features of CNS lymphoma versus toxoplasmosis

A

CNS lymphoma is hypermetabolic. Toxoplasmosis shows little or no FDG activity.

132
Q

Low PET Uptake by Malignant Tumors

A

Lobular breast carcinoma. Low-grade lymphoma. Salivary gland neoplasms. Necrotic primary tumors and lymph nodes.

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