Neuromuscular

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• Lambert-Eaton syndrome
  • Small cell lung cancer (SCLC)
• Myasthenia gravis
  • Thymoma

Neurological

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• Paraneoplastic cerebellar degeneration
  • Immune reaction against neural antigens in the cerebellum (e.g., Yo antigens of Purkinje cells, Tr antigens, Hu antigens)
  • Associated cancers
    • Anti-Yo antibodies: gynecological malignancies (breast, ovarian, or endometrial cancer)
    • Anti-Hu antibodies: small cell lung cancer
    • Anti-Tr antibodies: Hodgkin lymphoma
  • Clinical features
    • Ataxia, vertigo
    • Nystagmus, diplopia
    • Dysmetria, dysarthria

Endocrine

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Hypercalcemia of malignancy

• Etiology
  • Humoral hypercalcemia of malignancy (pseudohyperparathyroidism): PTHrP secretion by the tumor
    • Squamous cell carcinomas (lung, head, and neck)
  • Ectopic vitamin D production due to 1α-hydroxylase activity in tumor cells
    • Hodgkin lymphoma
    • NHL
  • Local osteolytic hypercalcemia: osteolytic activity at sites of skeletal metastases
    • Multiple myeloma
    • Breast cancer