USMLE Qbank Challenge

A 55-year old woman undergoes surgery for a stage II invasive ductal carcinoma. The mass is removed, with the specimen showing negative margins and no lymph node involvement. To determine treatment options, immunohistochemical studies are performed to evaluate expression of receptors for estrogen, progesterone, and HER2-type EGF. Which of the following markers will most likely show immunoreactivity that is limited to the nucleus?

A.

Estrogen and HER2 receptors

             

B.

Estrogen and progesterone receptors

C.

Estrogen, HER2, and progesterone receptors             

D.

Estrogen receptor only

E.

HER2 receptor only

F.

Progesterone receptor only                                                                                                          

The correct answer is B. Breast cancer is the second leading cause of cancer deaths among women. While surgical excision with negative margins and no lymph node involvement has a relatively good prognosis for the patient, an adjunct therapy involving either chemotherapy or radiotherapy is strongly recommended for high-grade cancers. In particular, tumors that express certain receptors such as estrogen, progesterone, and the HER2-type epidermal growth factor (EGF) receptors may make the lesion more susceptible to pharmacologic interventions, including the estrogen receptor antagonist tamoxifen and the HER2 EGF receptor blocker trastuzumab (Herceptin). Since both estrogen (choice D) and progesterone receptors (choice F) are steroid hormone receptors, they will mostly be located in the nucleus to act as transcription factors. These would appear as a nuclear pattern of staining.

In contrast, EGF receptors (choices A, C, and E) are tyrosine kinase receptors and will be largely localized in the cell membrane surface.

MedEssentials (2nd Ed.): pp. 399, 400, 401

First Aid (2008): pp. 450, 451

Estrogen receptor and progesterone receptor are steroid hormone receptors, and therefore are found in the cell nucleus; whereas HER2 receptor (which is in the family of epidermal growth factors) is on the cytoplasmic membrane.

Swollen eyes and brown urine

A 12-year-old girl is brought in by her mother, who reports dark brown urine and swelling around the daughter’s eyes. The patient may have complained about a sore throat 2 weeks prior. Which lab result would confirm the suspected diagnosis? A. Urinalysis positive for protein and red blood cells B. Serum BUN > 50 C. Serum negative for presence of anti-DNAse B antibodies D. Elevated serum C3 concentration E. Serum ASO titer > 1:330 ANSWER The suspected diagnosis is post-streptococcal glomerulonephritis. The dark brown urine suggests hematuria, and the periorbital edema suggests loss of protein. The history of pharyngitis and patient age point toward streptococcal cause, rather than one of the many other causes of hematuria and proteinuria. In the setting of a recent Group A strep infection, ASO titers (> 1:330), anti-DNAse B antibodies, and anti-hyaluronidase antibodies are frequently elevated. While UA will definitely show proteinuria and red cells, this confirms glomerulonephritis but not the specific entity. Serum C3 concentrations are usually decreased in the setting

The arachnoid villi responsible for cerebrospinal fluid absorption protrude mainly in the:

A. Superior saggital sinus

B. Inferior saggital sinus

C. Straight sinus

D. Transverse sinus






answer
D

explnation