A patient with cushinoid features presents with hemoptysis; he shows no response to dexamethasone suppression test; most likely diagnosis here is:
**Core Concept**
Cushingoid features indicate chronic hypercortisolism, which can arise from endogenous cortisol overproduction. Hemoptysis in such a setting suggests a pulmonary source, and lack of response to dexamethasone suppression test (DSST) indicates that the cortisol excess is not due to pituitary or adrenal sources but rather from an ectopic source, most commonly a lung tumor.
**Why the Correct Answer is Right**
Ectopic ACTH production by small cell carcinoma of the lung leads to autonomous stimulation of the adrenal cortex, causing Cushingoid features. These tumors often present with hemoptysis due to their location in the lung. Unlike pituitary or adrenal sources, ectopic ACTH causes cortisol overproduction that is **not suppressed** by dexamethasone, as the ACTH is not from the pituitary but from the tumor. This lack of suppression is a hallmark of ectopic ACTH syndrome.
**Why Each Wrong Option is Incorrect**
Option A: Adrenal hyperplasia typically presents with a **dexamethasone-suppressible** cortisol excess, and does not usually cause hemoptysis.
Option B: Adrenal adenoma usually causes **excess cortisol** but responds to dexamethasone suppression, and is not associated with hemoptysis.
Option D: Pituitary microadenoma causes Cushing’s disease and **does respond to dexamethasone suppression**, making it inconsistent with the patient’s lack of response.
**Clinical Pearl / High-Yield Fact**
In patients with Cushingoid features and hemoptysis, **lack of dexamethasone suppression** is highly suggestive of ectopic ACTH-producing tumor—most commonly **small cell lung cancer**. Always consider lung malignancy in such cases, especially when dexamethasone fails to suppress cortisol.
✓ Correct Answer: C. Ca lung with ectopic ACTH production