Paraneoplastic syndromes
by Subramani
Bronchogenic carcinoma can be associated with a number of paraneoplastic syndromes, some of which may antedate the development of a gross pulmonary lesion. The hormones or hormone-like factors elaborated include:
Antidiuretic hormone, including hyponatremia owing to inappropriate ADH secretion Adrenocarticotropic hormone (ACTH) producing Cushing syndrome Parathormone, parathyroid hormone-related peptide prostagladin E, and some c
ytokines, all implicated in the hypercalcemia often seen with lung cancer Calcitonin, causing hypocalcemia Gonadotropins, causing gynecomastia Serotonin, associated with the carcinoid syndrome. The incidence of clinically signicicant syndromes related to these factors ranges from 1 to 10% of all lung cancer patients, although a much hiher proportion of patients show elevated serum levels of these ( and other ) peptide hormones. Any one of the histologic types of tumors may occasionally produce any one of the hormones, but tumors producing ACTH and ADH are predominantly small cell carcinomas, whereas those producing hypercalcemia are mostly squamous cell tumors. The carcinoid syndrome is associated rarely with small cell carcinoma but is more common with the bronchial carcinoids.
Other systemic manifestations of bronchogenic carcinoma include the Lambert Eaton myasthenic syndrome in which muscle weakness is caused by autoimmune antibodies (possibly elicited by tumor ionic channels) directed to the neuronal calcium channel, peripheral neuropathy usually purely sensory; dematologic abnormalities including acanthosis nigricans; hematologic abnormalities, such as leukemoid reactions and finally a peculiar abnormality of connective tissue called hypetrophic pulmonary osteoarthropathy associated with clubbing of the fingers.
Apical lung cancer in the superior pulmonary sulcus tend to invade the neural structures around the trachea including the cervical sympathic plexus, and produce and group of clinical findings that includes severe pain in the distribution of the ulnar nerve and Horner syndrome (enopathalomos, ptosis, miosis, and anhidrosis) on the same sitde as the lesion. Such tumors are also referred as Pancoast tumors.
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