The first report of Paraneoplastic syndrome is attributed to a French physician, M Auche, who described the involvement in a peripheral nervous system in cancer patients in 1890. This syndrome is a group of signs and symptoms caused by a substance that is produced by a tumor, or in reaction to a tumor. Paraneoplastic syndrome is defined as a rare disorder triggered by a response to neoplasm of an immune system that is altered. These are clinical syndromes produced by tumor although they occur remotely from the tumor itself.
The symptoms may be of any nature – endocrine, neuromuscular or musculoskeletal, cardiovascular, cutaneous, hematologic, gastrointestinal, renal or miscellaneous. Fever is the most common sign. Other clinical symptoms may be benign but syndromes could be varied; from a malignant carcinoid syndrome to Cushing syndrome. In cancer patients, the central nervous system involvement can be detected and it is a prominent manifestation of cancer.
Because of their protean manifestations, Paraneoplastic syndromes are managed by a medical team of physicians, including medical oncologists, surgeons, radiation oncologists, endocrinologists, hematologists, neurologists and dermatologists.
This syndrome can be due to a number of causes, including hormones or biologically active products, made by tumor, which blocks normal hormone, autoimmunity, immune-complex production and immune suppression. But, this is not caused by the primary tumor itself, or by its metastases, or by compression, infection, nutritional deficiency, or treatment of tumor.
Patients with family history of malignancies are at an increased risk and should be screened for cancer. Paraneoplastic syndromes occur typically among middle-aged to older patients. They are mostly diagnosed with cancers of the lung, breast, ovaries, or lymphatic system or lymphoma.
These symptoms sometimes appear before the diagnosis of a malignancy. When the tumor breaks immune tolerance and begins to attack the normal tissue expressing that protein, this syndrome become prominent.
Types of Paraneoplastic Syndrome
Due to the complexity of this syndrome, its clinical presentations may vary greatly. Hence, Paraneoplastic syndromes is divided into four main categories - endocrine, neurological, mucocutaneous, and hematological syndromes as well as a host of others including rheumatologic, renal, gastrointestinal, Cutaneous and miscellaneous.
Fever, dysgeusia, anorexia, and cachexia are included under miscellaneous category. Fever is associated with lymphomas, acute leukemias, sarcoma and carcinomas.
Rheumatologic syndrome includes polyarthritis, particularly in patients with myelomas, lymphomas, acute leukemia, malignant tumors of the colon, pancreas, prostrate. Scleroderma may precede the evidence of tumor. Widespread form of malignancies of breast, uterus and lung can be observed.
Renal syndrome is characterized by hypokalemic nephropathy, and it occurs in 50% of individuals with ACTH secreting tumors of the lung. Nephrotic syndrome is observed in patients with Hodgkin lymphoma, non Hodgkin lymphoma, malignancies of lung, thyroid, colon, breast, ovary and pancreatic head.
Watery diarrhea and electrolyte imbalance, leads to asthenia, confusion and exhaustion, all characteristic of gastrointestinal syndromes. Severe prostaglandins lead to malabsorption and unavailability of nutrients.
Hematologic syndromes are related to anemia, thrombocytosis, disseminated intravascular coagulation, and leukemoid reactions from several types of cancers. Leukemoid reactions due to immature white blood cells in the blood stream are accompanied by hypereosinophilia and itching.
Cutaneous syndromes are manifested by itching and flushes, alopecia, or hypertrichosis. Blackish pigmentation of the skin usually occurs in patients with metastatic melanomas or pancreatic tumors.
Endocrine syndromes resemble common endocrine disorders. Increased serum and urine cortisol concentrations are common examples of this malignancy.
Neurologic or neuromuscular syndromes relate to cancers and such disorders affect 6% of all patients with cancer. Neuromuscular symptoms mimic common neurological conditions. Myasthenia gravis is a common Paraneoplastic syndrome in patients with thymoma, a malignancy arising from epithelial cells of the thymus.
Paraneoplastic limbic encephalitis is characterized by depression, seizures, irritability and short term memory loss and neurologic symptoms rapidly resemble dementia.
Paraneoplastic cerebellar degeneration causes gait difficulties, dizziness, nausea and diplopia. Sensory neuropathy affects lower and upper extremities and there is progressive memory loss, either symmetric or asymmetric.
As Paraneoplastic syndromes may evolve over weeks to months, they usually stabilize regardless whether the patient's underlying condition improves or worsens. Since this is the first manifestation of cancer, patients should undergo investigation for cancer. Other diagnoses are membrane disease, dementia, encephalopathy, encephalitis, myelitis, anemia, bone marrow failure, chronic fatigue syndrome, mixed connective tissue disease, polycythemia vera and polymyalgia rheumatica among others.
Complete laboratory tests in blood, urine, cerebrospinal fluid, protein electrophoresis, assays for auto antibodies, Endoscopy and imaging studies including whole body scans and FDG-PET scans are prescribed to detect extremely small tumors especially useful for patients with neurologic diseases.
Treatment of Paraneoplastic Syndrome
Treatment for this syndrome varies depending upon the type and location of tumors. The first option of treatment of the underlying tumor is by therapeutic protocols, a combination of surgery, radiation, chemotherapy. Second therapeutic option is for patients with clearly identifiable antibodies by intravenous immunoglobulins, steroids, or plasma exchange.
Surgical treatment is typically directed toward the underlying neoplasm although some Paraneoplastic disorders may resolve rapidly without surgery on the primary tumor.
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Bibliography / Reference
Collection of Pages - Last revised Date: February 3, 2023