A patient with cushingoid features presents with hemoptysis: he shows no response to dexamethasone suppression test; most likely diagnosis here is –
**Core Concept**
The patient's presentation of Cushingoid features with hemoptysis and failure to suppress cortisol levels with dexamethasone suggests an ectopic source of cortisol production, which can be caused by a tumor secreting adrenocorticotropic hormone (ACTH) or cortisol itself. This condition is known as Cushing's syndrome due to an ectopic source.
**Why the Correct Answer is Right**
The patient's failure to respond to dexamethasone suppression test indicates an abnormality in the hypothalamic-pituitary-adrenal (HPA) axis, which is a characteristic feature of ectopic ACTH-producing tumors. These tumors can be malignant and are often found in the lung, pancreas, or thymus. The ectopic ACTH-producing tumor stimulates the adrenal glands to produce excessive cortisol, leading to Cushing's syndrome. The hemoptysis in this patient suggests a possible lung tumor as the source of ectopic ACTH production.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided.
* **Option B:** This option is not provided.
* **Option C:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
Ectopic ACTH-producing tumors can be challenging to diagnose, and a high index of suspicion is required. The presence of Cushingoid features, failure to suppress cortisol levels with dexamethasone, and hemoptysis should prompt an investigation for a possible ectopic source of ACTH production.
**Correct Answer: C. Ectopic ACTH-producing tumor.**