Occult Non-small Cell Lung Cancer Presenting as Paraneoplastic Gastroparesis: A Case Report and Literature Review.

Paraneoplastic gastrointestinal syndromes rarely precede the actual detection of an overt cancer with gastroparesis being a very rare initial presentation. To increase the clinical awareness of this rare clinical entity, we present a case of severe gastroparesis that was later proven to be associated with an occult poorly differentiated non-small cell lung cancer. We then continue to briefly review the relevant literature on paraneoplastic gastrointestinal syndromes to date. A 61-year-old African-American man presented with two months history of severe post-prandial nausea, vomiting and bloating associated with unintentional weight loss of 20 pounds. General physical examination revealed cachexia, temporal muscle wasting and clubbing of nails in both hands. The following investigations were normal or negative: basic metabolic panel, liver function tests, chest X-ray and esophagogastroduodenoscopy. Computed tomography (CT) scan of the abdomen showed residual food in the stomach and scintigraphic gastric emptying studies were consistent with gastroparesis. CT scan of the chest was performed which revealed a spiculated nodule sized 9 mm in right upper lobe of the lung with right hilar lymphadenopathy. Positron emission tomography (PET) scan revealed hyper-metabolic activity in the right upper lobe nodule and right hilar adenopathy. Nodule resection and biopsy revealed a poorly differentiated non-small cell lung carcinoma. Due to the concern of paraneoplastic origin of his gastroparesis further serological testing showed positive anti-neuronal nuclear antibodies type 1 (Anti-Hu) and cytoplasmic purkinje cell antibodies (Anti-Yo). The patient was started on a chemotherapy combination of Carboplatin and Paclitaxel with a three-week course of local radiation therapy. Moreover, for the relief of his severe gastrointestinal (GI) symptoms dietary modifications, pro-kinetic agents and psychological counseling were used with gradual clinical improvement observed on follow-up visits.