UW Qbank repeatedly missed

Question 1

Differential diagnosis for ANTERIOR mediastinal mass

Answer 1

4 T’s:
Thymoma
Teratoma (& other GCT)
“Terrible” lymphoma
Thyroid neoplasm

Question 3

differential diagnosis of anterior mediastinal masses includes

Answer 3

the 4 Ts: thymoma, teratoma (and other germ cell tumors [GCTs]), “terrible” lymphoma, and thyroid neoplasm.

Question 4

MLD: Young man w/ anterior mediastinal mass & elevated serum hormone levels of alpha fetoprotein (AFP) and β-hCG

A) high grade lymphoma
B) mixed GCT
C) seminoma
D) small cell neuroendocrine tumor
E) thymoma

Answer 4

B) mixed GCT

malignant GCTs can be broken down into subtypes:

-Seminomas (more common) than may cause elevated serum β-hCG in a minority of cases, but AFP is almost always normal
-Nonseminomatous GCTs, (ie yolk sac tumors choriocarcinoma, embryonal carcinoma, and mixed GCTs that contain a mixture of different cell types), cause an elevated AFP and/or β-hCG in the majority (~85%) of patients.

Question 6

A new assay for Lyme disease has been developed. Well, the Asae has been tested extensively in Maine. A group of investigators is planning to test it in California in comparison to the assay performance in Maine. The testing assay in California would affect the performance of the assay in which of the following ways?

Decreased negative likelihood reissue of the Lyme disease assay

Lower likelihood that a patient without Lyme disease truly has a negative test

Greater likelihood that an individual with a positive positive test will truly have Lyme disease

Decreased positive likelihood ratio of the Lyme disease assay

Lower likelihood that a patient with Lyme disease will truly have a positive test

Greater likelihood that an individual with a negative test will truly not have Lyme disease


Answer 6

Greater likelihood that an individual with a negative test will truly not have Lyme disease

Recall that negative predictive value is inversely related to the prevalence. The negative predictive value increases as the disease prevalence decreases positive predictive value, directly correlates with prevalence, and thus prevalence leads to decreased positive value.

Prevalence does not influence, intrinsic test characteristics, like sensitivity, or specificity, negative likelihood ratio or positive likelihood ratio 

Question 7

How does prevalence affect sensitivity, specificity negative likelihood ratio and positive likelihood ratio

Answer 7

 It doesn’t

Question 8

How does disease prevalence impact negative predictive value and positive predictive value?

Answer 8

As prevalence decreases, negative predictive value will increase and positive positive predictive value will decrease

In other words, prevalence and negative predictive value are inversely related wow prevalence and positive predictive value are directly related