Paraneoplastic syndrome
Reading File
Finding Sources
Searching PubMed
paraneoplastic syndrome
Finding Sources
Finding Sources
Reading File
Reading File
Reading File
Reading File
I now have sufficient content from multiple authoritative sources to write a thorough answer. Let me compile the complete response.
Paraneoplastic Syndromes
Paraneoplastic syndromes are the remote effects of malignancy that cannot be attributed to direct tumor invasion, compression, or metastasis. The term derives from the Greek "alongside cancer." They affect up to 15% of all cancer patients (dropping to a few percent when cachexia is excluded). Critically, up to two-thirds present before the associated malignancy is diagnosed, so recognizing them often leads to earlier cancer detection. Their course generally mirrors the tumor - effective cancer treatment usually improves the syndrome, and recurrence may be heralded by the syndrome's return.
- Goldman-Cecil Medicine, p. 1886
Classification by System
1. Endocrine / Humoral Paraneoplastic Syndromes
These result from ectopic hormone production by tumor cells.
| Syndrome | Mediator | Associated Tumors |
|---|---|---|
| Humoral hypercalcemia of malignancy | PTHrP | Squamous cell carcinoma (lung, H&N), breast, RCC, melanoma, prostate |
| Hypercalcemia (calcitriol-mediated) | 1,25-(OH)2 vitamin D | Lymphoma |
| Ectopic ACTH / Cushing syndrome | POMC / ACTH / CRH | SCLC, pulmonary carcinoid, medullary thyroid cancer, islet cell tumor, pheochromocytoma |
| SIADH | Ectopic vasopressin | SCLC, squamous head & neck cancer |
| Hypoglycemia | IGF-2 (NICTH) | Insulinoma, large sarcomas / retroperitoneal tumors |
| Erythrocytosis | Erythropoietin | Renal cell carcinoma, hepatocellular carcinoma |
| Gynecomastia / precocious puberty | hCG | Choriocarcinoma, testicular embryonal carcinoma, seminoma |
Key clinical details:
- Humoral hypercalcemia is the most common life-threatening paraneoplastic endocrinopathy. PTHrP binds PTH receptors, causing osteoclast activation and renal calcium reabsorption. Treatment: aggressive IV saline + bisphosphonates (for serum Ca >13 mg/dL) + treat underlying tumor.
- Ectopic ACTH from SCLC causes a rapid-onset Cushing syndrome often dominated by hypokalemia, alkalosis, hyperglycemia, and muscle weakness rather than classic features (the classic habitus requires months to develop). SCLC secretes POMC; carcinoid tumors secrete ACTH or CRH.
- SIADH presents with euvolemic hyponatremia + inappropriately concentrated urine. Managed with free water restriction ± demeclocycline.
2. Neurologic Paraneoplastic Syndromes
These are mostly immune-mediated - the tumor expresses antigens shared with nervous system tissue, triggering autoantibodies and T-cell responses. SCLC is the most common underlying cancer.
| Syndrome | Key Feature | Antibody | Common Tumor |
|---|---|---|---|
| Lambert-Eaton myasthenic syndrome (LEMS) | Proximal weakness that improves with sustained contraction; autonomic features | Anti-VGCC (P/Q-type) | SCLC (60%) |
| Limbic encephalitis | Memory loss, psychiatric symptoms, seizures, medial temporal FLAIR changes on MRI | Anti-Hu, anti-NMDAR, anti-LGI1, anti-GABA-B | SCLC, thymoma, teratoma |
| Cerebellar degeneration | Rapid progressive ataxia | Anti-Yo (Purkinje cells), anti-Hu | Ovarian, breast, SCLC |
| Opsoclonus-myoclonus | Random, conjugate, multi-directional saccades + myoclonus ("dancing eyes, dancing feet") | Anti-Ri | Breast, SCLC, neuroblastoma (children) |
| Sensory neuronopathy | Severe painful sensory loss, proprioceptive loss, pseudoathetosis | Anti-Hu | SCLC |
| Stiff-person syndrome | Progressive rigidity of trunk and limbs, painful spasms | Anti-GAD, anti-amphiphysin | Breast, SCLC, thymoma |
| Encephalomyelitis | Multi-level CNS involvement | Anti-Hu | SCLC |
| Dermatomyositis / polymyositis | Proximal myopathy, elevated CK, Gottron papules, heliotrope rash | Anti-Jo-1, others | Lung, ovary, GI, lymphoma |
| Myasthenia gravis | Fatigable weakness, ptosis, diplopia | Anti-AChR | Thymoma (~15% of MG), thymic hyperplasia |
Key antibody groups:
- Intracellular ("onconeural") antibodies (anti-Hu, anti-Yo, anti-Ri, anti-Ma2, anti-amphiphysin): associate with T-cell-mediated neuronal destruction; syndromes are often irreversible and poorly responsive to immunotherapy.
- Cell-surface antibodies (anti-NMDAR, anti-LGI1, anti-CASPR2, anti-AMPAR, anti-GABA-B, anti-VGCC): functionally alter receptors; syndromes are more reversible with immunotherapy.
Notable specific syndromes from Harrison's (2025):
-
LGI1 antibody encephalitis: males >50 yrs; faciobrachial dystonic seizures (brief, distal arm/face) preceding classic limbic encephalitis; hyponatremia; <5% have thymoma; responds to immunotherapy but ~2/3 retain memory deficits.
-
CASPR2 antibody syndrome: >50 yrs; triad of encephalopathy + peripheral nerve hyperexcitability (neuromyotonia) + dysautonomia; Morvan syndrome (CASPR2 + prominent sleep dysfunction + "agrypnia excitata") associated with thymoma in ~50%.
-
GABA-B receptor encephalitis: limbic features + prominent seizures; >50% have SCLC or neuroendocrine lung tumor.
-
mGluR5 antibody encephalitis: strongly associated with Hodgkin lymphoma (Ophelia syndrome); highly responsive to tumor treatment.
-
Harrison's Principles of Internal Medicine, 22E, pp. 801-815
-
Goldman-Cecil Medicine, p. 1886-1888
3. Dermatologic Paraneoplastic Syndromes
| Skin Finding | Associated Tumor |
|---|---|
| Acanthosis nigricans | GI adenocarcinoma (especially gastric) |
| Dermatomyositis | Lung, ovary, GI, lymphoma |
| Leser-Trelat sign (sudden eruption of multiple seborrheic keratoses) | GI adenocarcinoma |
| Paraneoplastic pemphigus | Lymphoma, CLL, thymoma, Castleman disease |
| Erythema gyratum repens | Lung, esophageal cancer |
| Hypertrichosis lanuginosa acquisita | Lung, colorectal cancer |
| Necrolytic migratory erythema | Glucagonoma |
| Sweet syndrome | AML, myeloproliferative disorders |
Paraneoplastic pemphigus - also called paraneoplastic autoimmune multiorgan syndrome (PAMS) - involves circulating autoantibodies targeting desmoplakin and other cytoskeletal proteins, producing severe mucocutaneous blistering resistant to steroids. - Dermatology 2-Volume Set, 5e
4. Rheumatologic Paraneoplastic Syndromes
| Finding | Associated Tumor |
|---|---|
| Hypertrophic osteoarthropathy (periosteal new bone formation, clubbing, painful arthropathy) | Lung cancer (especially adenocarcinoma) |
| Palmar fasciitis and polyarthritis | Ovarian cancer |
| Carcinoma polyarthritis | Breast, lung, colon |
| RS3PE (remitting seronegative symmetric synovitis with pitting edema) | Hematologic malignancies |
| Raynaud phenomenon | Multiple myeloma, lymphoma |
| Vasculitis | Lymphoma, leukemia |
- Goldman-Cecil Medicine; Rheumatology 2-Volume Set
5. Hematologic Paraneoplastic Syndromes
| Abnormality | Mechanism | Common Tumor |
|---|---|---|
| Erythrocytosis | Ectopic EPO | RCC, hepatocellular carcinoma, cerebellar hemangioblastoma |
| Anemia of chronic disease | Cytokines (IL-6, hepcidin) | Wide range |
| Autoimmune hemolytic anemia | Autoantibody | CLL, lymphomas |
| Thrombocytosis | Reactive (IL-6, thrombopoietin) | Many solid tumors |
| DIC | Tumor procoagulants | Mucin-secreting adenocarcinoma, AML (APL) |
| Trousseau syndrome (migratory thrombophlebitis) | Mucin-activated clotting | Pancreatic, GI, lung cancer |
| Pure red cell aplasia | Autoimmune against RBC precursors | Thymoma |
- Goldman-Cecil Medicine, p. 1888
6. Renal and Hepatic Paraneoplastic Syndromes
- Glomerulopathy: Membranous nephropathy (associated with solid tumors - lung, colon, gastric; antibodies to PLA2R are absent in paraneoplastic forms), minimal change disease (Hodgkin lymphoma), MPGN (CLL, lymphoma).
- Hepatic dysfunction (Stauffer syndrome): Reversible cholestatic hepatopathy without hepatic metastases, seen with RCC. Resolves with nephrectomy.
Diagnostic Approach
The Goldman-Cecil stepwise approach:
- Characterize the abnormality; obtain labs and biopsy as needed
- Eliminate common causes first
- If no obvious etiology, consider paraneoplastic syndrome
- Screen for malignancy: physical exam (breast, GYN, prostate), CBC/chemistry/urine, CXR, mammogram
- CT abdomen/pelvis or PET scan if suspicious findings
- Antibody testing (paraneoplastic neurologic panels) and/or skin biopsy as indicated
- Treat the cancer; consider immunosuppressive therapy for paraneoplastic symptoms
Treatment Principles
- Treat the underlying tumor - this is the most effective intervention. Tumor regression often leads to syndrome remission.
- Immunotherapy for immune-mediated syndromes (especially cell-surface antibody syndromes): high-dose corticosteroids, IV immunoglobulin (IVIg), plasma exchange, rituximab, mycophenolate.
- Symptomatic management: 3,4-diaminopyridine for LEMS; antiepileptics for seizures; anticholinesterases are less effective in LEMS than in MG.
- Syndromes mediated by intracellular antigens (anti-Hu, anti-Yo) are often irreversible even with treatment, because neuronal loss is T-cell mediated.
Sources:
- Goldman-Cecil Medicine International Edition, Chapter 164 (Paraneoplastic Syndromes), p. 1883-1890
- Harrison's Principles of Internal Medicine, 22E (2025), Chapter on Autoimmune Encephalitis and Paraneoplastic Neurologic Syndromes
- Rheumatology, 2-Volume Set (2022, Elsevier)
- Dermatology 2-Volume Set, 5e
- Morgan and Mikhail's Clinical Anesthesiology, 7e
This is a shared conversation. Sign in to Orris to start your own chat.