Question

Paraneoplastic manifestations in small cell lung carcinoma.

Hint:

Early recognition of paraneoplastic syndromes in small cell lung carcinoma can guide treatment decisions and improve patient outcomes.

Answer 1

Small cell lung carcinoma (SCLC) is an aggressive form of lung cancer that can present with various paraneoplastic manifestations. These manifestations occur due to the ectopic production of hormones or hormone-like substances by tumor cells. Paraneoplastic syndromes in SCLC are often associated with poor prognosis.
Step 1: Common Paraneoplastic Manifestations:
1. SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion): This is the most common paraneoplastic syndrome in SCLC. It leads to hyponatremia due to excessive secretion of ADH.
2. Cushing’s Syndrome: Occurs due to ectopic production of ACTH (Adrenocorticotropic hormone), which stimulates cortisol release, causing symptoms like weight gain, hypertension, and hyperglycemia.
3. Lambert-Eaton Myasthenic Syndrome (LEMS): Characterized by muscle weakness and is caused by autoantibodies against presynaptic voltage-gated calcium channels.
4. Hypercalcemia: May occur due to the production of parathyroid hormone-related protein (PTHrP), which increases calcium levels.
Step 2: Diagnostic Approach:
1. Serum and urine tests for sodium and cortisol levels to identify SIADH and Cushing's syndrome.
2. Antibody tests for Lambert-Eaton myasthenic syndrome.
3. Measurement of PTHrP and calcium levels for hypercalcemia.