Paraneoplastic syndromes

Sx: tachypnoea, SOB, cough

Signs: decreased chest expansion, mediastinal shift (often normal but may shift AWAY from effusion, usually apex shift rather than tracheal due to gravity), decreased vocal fremitus/resonance, dull to percussion, reduced air entry, may have bronchial breathing above air-fluid level (aegophony), whispering pectoriloquy, may have pleural rub above air-fluid level if pleura inflamed

Commonly occurs in lung cancer.

May be due to extrinsic compression or invasion of SVC. Commonly occurs in small cell lung cancer, also in lymphoma/other lung Ca, can be non-neoplastic.

Sx: facial oedema, head fullness, raised non-pulsatile JVP, distension of chest wall veins (in SVC distribution), arm oedema, facial plethora, chest pain, cough. Sx may be exacerbated on bending forward/lying down. May be quick or gradual onset.

CXR signs: may be normal, superior mediastinal widening, pleural effusion, right-sided hilar mass, anterior mediastinal mass, cardiomegaly, bilateral diffuse infiltrates, calcified paratracheal nodes.

Rx: treat underlying disease (chemo)

Most common electrolyte disturbance of malignancy. Often due to bony mets. Only a true paraneoplastic syndrome if related to PTHrP.

Sx: nausea, confusion, constipation, polyuria, polydipsia, dehydration, arrhythmias

PTHrP 100x more potent than PTH. Mostly produced by squamous cell lung Ca. Others include squamous cell renal/head+neck/oesophageal. Rarer in breast Ca (usually due to bony mets).

MUST DO serum corrected calcium if suspect this- metabolic emergency.

Ix: serum corrected calcium > 2.7, decreased serum chloride, hypercalciuria, decreased PTH, increased urinary phosphate

Rx: IV saline 1st, then IV bisphosphonates

Most common endocrine paraneoplastic syndrome. Usually from small cell lung cancer (also pancreatic Ca, prostate Ca, non-Hodgkin's lymphoma, CNS disease, pulmonary disease, some drugs)

Sx: often asymptomatic but may have CNS toxicity (headaches, fatigue, altered mental state, confusion, seizures).

Ix: exclude non-neoplastic causes, hyponatraemia, normal serum albumin + glucose, serum hypo-osmolality, urin osmolarity > serum osmolarity, high urinary sodium, non-suppressed ADH

Rx: fluid restrict, democlocycline for other Sx

Ectopic ACTH production, usually from SCLC (50%), also from NSCLC, pancreatic Ca, thymic Ca, carcinoid tumours, phaeochromocytoma, medullary thyroid Ca

Sx: wt gain, central obesity, easy bruising, hirsutism, striae, impaired glucose metabolism, muscle wasting, osteoporosis, amenorrhoea, fatigue, weakness, hypokalaemia, metabolic alkalosis

Presentation: rapid onset, weakness secondary to proximal myopathy, hyperpigmentation, metabolic disturbances

Dx: clinical features, high serum/urinary cortisol, high ACTH, no response to high dose dexamethasone suppression test

Rx: specific anti-tumour Rx, if required decrease cortisol secretion (bilateral adrenalectomy, octreotide, ketoconazole, aminogluthethamide)

Occurs in pituitary tumours, gestational trophoblastic tumours, germ cell tumours, hepatoblastomas, lung Ca

Ix: elevated beta-hCG (urine test as this is faster), gynaecomastia, testicular exam (especially in young patients), CXR/CT chest

Beta-hCG is secreted by lung tumours, GI tract tumours, adrenal tumours, genitourinary tumours and hepatoblastoma. Levels usually correlate with clinical signs

Commonly in SCLC, also breast and ovarian Ca and non-Hodgkin's lymphoma

Perivascular inflammation and neuronal degeneration, may affect limbic system/brainstem/spinal cord. Loss of neurons in amygdala + hippocampus, insular cortex gliosis, lymphocyte cuffing of blood cells, microglial nodules.

Sx: slow subacute onset, progressive, loss of short term memory, hallucinations, seizures, personality changes

Ix: CSF (increased protein, IgG and lymphocytes- pleocytosis), anti-Hu Ab, MRI changes

Rx: anti-tumour therapy

Lambert-Eaton myasthenic syndrome.

Ab-mediated, usually with underlying malignancy (60% cases). Mostly in SCLC, also breast/thymic/GI tract Ca.

Sx: proximal muscle weakness, 30% have dysphagia, Sx improve briefly on starting exercise then get worse again

Dx: EMG

Rx: steroids, treat Ca, plasma exchange (generally effective)

Cholinesterase inhibitors usually ineffective (constrast with myasthenia gravis)