A 32-year-old Caucasian woman was seen because of a 40 pound weight gain over the last two years. Patient has been having headaches and has been emotionally labile. She complained of generalized weakness, irregular and infrequent menstrual periods and has noticed some hair growth on the face for the last year. Past and family history are non-contributory. She is a non-smoker, non-alcoholic and is on no medicines. Thyroid function tests and prolactin done by her private M.D. six months ago were normal.

On examination - P = 90/m reg, BP= 160/100 mm/Hg. Generalized obesity with slight centripetal distribution. Height= 5'6", weight = 185 pounds.

HEENT - Face slightly rounded and plethoric, dark hair present on the chin, upper lip and legs, acne marks present. Visual fields are normal.

No thyromegaly or adenopathy. Chest and CVS normal.

Abdomen - obese with violaceous striae on the lower abdomen and in the axillary region.

CNS - Depressed mood, power 4/5 in proximal muscles of upper and lower extremities with some wasting.

Extremities - some ecchymoses on arms and thighs.

Sodium = 140 mM/L (n = 136-146), potassium = 3.5 mM/L (n = 3.5-5.3), chloride = 98 mM/L (n = 98-108) carbon dioxide = 28 mM/L (n = 20-32), BUN = 14 mg/dl (n = 7-22), creatinine = 1 mg/dl (n = 0.7-1.5), glucose = 214 mg/dl (n = 70-110). CBC, urinalysis and chest x-ray was normal.

1. What is the clinical diagnosis? What clinical manifestations help to determine this diagnosis?
Cushing's syndrome.

2. What initial test(s) can be done to assess this condition?

3. What is the differential diagnosis after the screening test(s) has confirmed your clinical diagnosis.

Dexamethasone 0.5 mg PO Q 6 hours is given for 2 days and then 2.0 mg PO Q 6 hours for 2 days. Blood and urine samples are collected at baseline and daily for serum cortisol, urine free cortisol (UFC) and 17 (OH) corticosteroid [17 (OH) CS]. Results are shown in the following table:

4. With this information what is the diagnosis in this patient?

5. What therapeutic strategy would you recommend?