AB 36. Primary lung carcinoid, a rare cause of paraparesis: report of a case and review of the literature

Background: Carcinoids are neuroendocrine tumors involving the gastrointestinal tract, lungs and bronchi. They are usually benign with slow growth, but they can be malignant (metastasizing to liver, lungs, bones, skin, etc). Endocrine activity results in carcinoid syndrome: Intestinal carcinoid [5-hydroxytryptamine (serotonin) to portal circulation]: abdominal cramps, diarrhoea, bronchospasm, face/chest cyanotic flushes, right-sided stenotic cardiac lesions. Lung carcinoid (histamine and 5-hydroxytryptophan to systemic circulation): red facial flush/oedema, salivation, lachrymation, potentially tachycardia, fever, anxiety, tremor, hypotension, left-sided cardiac lesions). We present an extremely rare case of primary lung carcinoid presented with paraparesis.
Patient and methods: A 69 year old man developed progressively deteriorating bilateral proximal muscular weakness of the legs that within 6 months led to paraparesis (inability to stand up and walk) with preserved sensation. Electromyography showed polyneuropathy. History, clinical and laboratory data excluded diabetis mellitus, hypothyroidism, renal/liver failure, cachexia, alcohol abuse, chemotherapy, drug or other toxicity. Magnetic resonance imaging excluded spinal cord or spinal nerve root compression. Computed tomography revealed a small peripheral paracardiac right-middle lobe tumor (maximal diameter:1.8cm). Thoracoscopic wedged resection was performed (endo-stappler). Histology revealed lung carcinoid of low mitotic index (1-2%).
Results: The patient had an uneventful recovery, was discharged on the 5th postoperative day to a rehabilitation centre, where he remained for 3 months. Progressive motor function improvement was noted; paraparesis resolved completely within 6 months. At 1-year follow-up normal respiratory and neurological status was noted, in the absence of carcinoid recurrence or metastasis.
Conclusions: Myopathy is common in endocrine disease and cancer can have endocrine and metabolic activities and cause neurological complications. Encephalopathy, myelopathy, and more often motor and sensory neuropathy, myopathy, or neuromyopathy of central distribution may occur in paraneoplastic syndromes. Neuromyopathy has been reported in 14% of lung cancer patients. There are reports of recurrent facial palsy in metastatic thymic carcinoid, proximal muscle weakness in ACTHreleasing thymic carcinoid, an ACTH-releasing bronchial carcinoid, and paraparesis 40 years after pneumonectomy for carcinoid adenoma induced by inflammatory contents of the pneumonectomy cavity. To the best of our knowledge there is no report of paraparesis induced by primary pulmonary carcinoid. Complete resolution after excision suggests “paraneoplastic” syndrome.